HEADNEWS: THE ELECTRONIC NEWSLETTER OF THE
HIGH ENERGY ASTROPHYSICS DIVISION OF THE AAS
|
Newsletter No. 89, November 2006 |
- Notes from the Editor
- Christine Jones
- The View from the HEAD
Chair
- Steve Murray
- News from NASA
Headquarters -
Lou Kaluzienski and Rick Harnden
- HEAD in the News -
Ilana Harrus, Christopher Wanjek and Megan Watzke
- Chandra X-ray
Observatory Operations Report - Roger Brissenden and Martin
Weisskopf
- XMM-Newton Mission
News - Randall Smith and Phil Plait
- INTEGRAL Mission News
- Christoph Winkler
- RHESSI Mission News -
David Smith
- Swift Mission News -
Padi Boyd, Lynn Cominsky, Neil Gehrels & Phil Plait
- RXTE News - Padi
Boyd, Gail Rohrbach, Evan Smith,
Jean Swank, Craig Markwardt, Tod Strohmayer
- Suzaku Mission News
- Koji Mukai and Ilana Harrus
- GLAST Mission News -
Christopher Wanjek, Steven Ritz and Phil Plait
- Constellation-X News
-- Mike Garcia
- LISA News -- Bonny Schumaker
- Meeting
Announcements
from the Editor - Christine Jones, HEAD Secretary-Treasurer,
headsec@cfa.harvard.edu, 617-495-7137
HEAD only delivers the table-of-contents for HEADNEWS into your mailbox.
The newsletter itself can be found online at
http://www.aas.org/head/headnews/headnews.nov06.html.
A very successful HEAD Division meeting was held in San Francisco from
October 4-6. Our thanks to John Vallerga and the Eureka Scientific team for
organizing the meeting (including the dinner cruise and fireworks!) and to
Judy Johnson of the AAS for putting together the program abstracts.
Pictures from the meeting can be found at
http://lheawww.gsfc.nasa.gov/users/imh/HEAD2006/
Ballots for the HEAD election of three new members of the Executive
Committee have been emailed to HEAD members. The candidates are
Steve Boggs, Wei Cui, Mike Eracleous, Vicky Kalogera, Cole Miller,
and Ron Remillard. Please remember to vote
before the December 15, 2006 deadline.
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2. The View from the HEAD Chair - Stephen Murray
The big news is that the HEAD meeting in San Francisco,
October 4-7, 2006 was a huge success! It was the
largest meeting of the HEAD (> 430 registrations),
topping even the Hawaii 2000 event. Not only was the
meeting large in attendance, but it was also large in
content. Thanks to all of the participants for bringing
such an array of new results to the meeting. A special
thanks to the conference organizers from Eureka
Scientific and also the local organizing committee from
CU Berkeley. At the meeting the David N. Schramm Award
for High Energy Astrophysics Science Journalism was
awarded to Trudy Bell for her articles on LIGO. The
award was presented at the meeting banquet.
There will be two special HEAD sessions at the January
AAS meeting in Seattle. One will be on Short GRB's and
other on GLAST. We will also have a Rossi Prize Lecture
session featuring three talks by the winners, Tod
Strohmayer, Deepto Chakrabarty, and Rudy Wijnands. The
annual HEAD business meeting is also scheduled at
Seattle, I look forward to seeing many of you there.
During the HEAD-AAS meeting, the Executive Committee met
to being the planning process for our next divisional
meeting. It will be held in April 2008, and most likely
will be sited in the San Francisco Bay Area. Mark your
calendars for this next meeting and stay tuned for more
details as they are developed.
As everyone knows, there is very little firmly in the NASA science
plan beyond 2010. For High Energy Astrophysics, the launch of GLAST in
2007 is the last new mission that is approved and scheduled. As a
result High Energy Astrophysics faces a potential hiatus of new
missions in the decade of 2010. The Beyond Einstein program, is an
approved program with two flagship missions (LISA and Constellation-X)
and three probes (Black Hole Finder, Cosmic Inflation, and Dark
Energy). However, the order in which these missions will be carried
out, and their time frames, are not yet established. NASA and DOE have
asked the NRC Board on Physics and Astronomy to conduct a review of
the BE Program and to make a recommendation as to which mission should
go first, so that it might start before the end of this decade (i.e.,
before the next Decadal Survey). The review will also provide some
input to the Decadal Survey regarding the ordering of the remaining BE
missions. This effort is just getting underway, and more details
including the committee members can be found at this web site:
http://www7.nationalacademies.org/bpa/Beyond_Einstein.html
Once again, a reminder about the next HEAD meeting
April 2008, and the closer HEAD sessions at the January
AAS meeting in Seattle. See you there.
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3. News from NASA Headquarters
- Rick Harnden and Lou Kaluzienski
Personnel developments
Lou Kaluzienski has returned to his position as High Energy
Astrophysics Discipline Scientist in the Astrophysics Division at NASA
Headquarters from a 14-month detail at Goddard Space Flight Center
where he served as chief of the Observational Cosmology Lab. He
rejoins his HEA colleagues Wilt Sanders and Rick Harnden who have both
extended their assignments in the Division for an additional two
years. In addition to his Discipline Scientist responsibilities, Wilt
has assumed the position of Division Lead for the R&A program, which
includes oversight of the APRA, ATP, and ADP programs. Rick will
continue serving as Program scientist on the GLAST, Swift, and
INTEGRAL missions in addition to managing the gamma-ray portion of the
HEA SR&T program.
The advertisement for the currently vacant position of Astrophysics
Division Director will close on October 31. Rick Howard has been
acting in that capacity for the past 8 months and it is anticipated
that a selection will be made as soon as the normal SES administrative
process permits. The Associate Administrator for the Science Mission
Directorate, Mary Cleave, has announced her intent to retire next
Spring. It is expected that an announcement for the position will be
released in late 2006/early 2007.
Selection Announcements
As of this writing, the selection of proposals submitted in response
to the ROSES-06 solicitation for participation in the Astronomy and
Physics Research & Analysis (APRA) Program will be announced by the
end of October. The notification letters are in final preparation and
their release has been awaiting resolution of lingering budget issues.
The review of proposals submitted in response to the Astrophysics
Theory Program/Beyond Einstein Foundation Science (ATP/BEFS) Program
solicitation has been completed and formulation of the selection
recommendation is in preparation. The ATP/BEFS lead scientist, Ron
Hellings, anticipates that the results will be announced before the
end of November.
Budget News
NASA is currently operating under a Continuing Resolution which is
scheduled to expire in mid-November. Limited funding is available for
the development/operation of ongoing flight programs and partial
support of the R&A program. Due to the funding situation, some delays
to grant renewals nominally planned for the first quarter of the
fiscal year are anticipated.
NAS Review of Beyond Einstein Program
NASA has asked the Space Studies Board of the NRC to perform an
assessment of the missions comprising the Beyond Einstein (BE)
Program, including the two Einstein Observatories (Con-X and LISA) and
three Einstein Probes (Black Hole Finder Probe, Joint Dark Energy
Mission, and Inflation Probe). Specifically, the SSB has been charged
with the task of identifying which of the five BE missions should
proceed first and to assist NASA in its investment strategy for future
technology development within the BE program. The criteria for this
assessment include the potential scientific impact and the realism of
the preliminary technology and management plans and cost estimates of
each mission. The requested timeframe for completion of this study is
early September of next year.
APRA/2007
Due to the lateness of the planned release date of the ROSES-07
solicitation and our desire to maintain the same annual schedule for
the APRA program, it is currently expected that next year's APRA
solicitation will be issued as an amendment to the ROSES-06
announcement. Based upon SMD policy, all amendments to ROSES-06 must
be released no later than January 5, 2007.
4. HEAD in the News
- Ilana Harrus, HEAD Press Officer,
Christopher Wanjek, Structure and Evolution of the Universe
Senior Science Writer, and Megan Watzke, Chandra Press Officer
There is much news to report since the last newsletter.
The April press telecon coordinated by NASA Goddard featuring news of
the first complete gravitational wave computer simulation of a black
hole merger was a big hit. Although esoteric, the result (with help
of killer graphics and a well-coordinated press event) scored the
front-page above-the-fold lead story in the New York Times Science
Times, and made the other major papers (Washington Post, USA Today),
all the science magazines, as well as national radio and local TV.
RXTE had a few solid hits. Tod Strohmayer and Anna Watts' observation
of neutron star seismology (May) made USA Today, science magazines and
German newspapers. John Middleditch's result about neutron star
glitches (June) scored New Scientist and various website coverage. In
July, the result on RS Ophiuchi (Jennifer Sokoloski et al.) garnered
broad coverage on the web, including CNN, in the science magazines,
and in European newspapers such as The Times.
XMM-Newton had a hit in June with a result on Abell 3266 (Finoguenov
et al.). It secured coverage in USA Today, L.A. Times, and various
web sites and magazines. Andrea De Luca et al. followed with an
RCW103 observation (July), which received modest coverage on
Space.Com, New Scientist and the UPI newswire.
INTEGRAL had some coverage for Volker Beckman's hard X-ray census
(July), in Space.Com and European outlets.
Chandra results were featured in three NASA's phone-in press
conferences, known as "media telecons." All three events generated
significant coverage, but the result on dark matter (August 21st) was
by far the most successful. For example, that story was featured on
the front page of the Washington Post -- perhaps the first time
Chandra or X-ray astronomy has garnered such attention. In addition
to the Washington Post, the story was covered by the New York Times (a
separate picture and editorial), USA Today, NPR ("All Things
Considered" and "Science Friday"), The Economist, Time, Newsweek,
Voice of America, Seed Magazine, PhysicsWeb, Chemical & Engineering
News, Science News, Minneapolis Star Tribune, Boston Globe, CNN
International, Space.com, Sydney Morning Herald, BBC News, San Jose
Mercury News, Houston Chronicle, Advertiser Adelaide (Australia),
Daily Telegraph (Australia), Independent Online (South Africa),
Malaysia Star, Hindustan Times, Scientific American.com, USA Today,
Register (UK), People's Daily Online (China), Seattle Post
Intelligencer, San Francisco Chronicle, Fox News, CBS News.com, CTV.ca
(Canada), BBC News.com, National Geographic.com, Globe and Mail
(Canada), MSNBC.com, Mumbai Mirror (India), Aljazeera.net, Reuters,
News24 (South Africa), The Australian, Seattle Times, Scotsman, ABC
News.com, Detroit Free Press, Xinhua (China), New Scientist Space.com,
Fort Wayne Journal Gazette (Indiana), PhysOrg.com, Pioneer Press
(Minn.), Grand Forks Herald (North Dakota), Columbus Ledger-Enquirer
(Georgia), Biloxi Sun Herald, San Luis Obispo Tribune (Calif.), Contra
Costa Times (Calif.), The Benton Crier (Iowa), Times of Oman, Science
Now, Indianapolis Star, Newsday (NY), Discovery Channel.com,
Nature.com, Montreal Gazette, The Columbus Dispatch (Ohio), Aviation
Week & Space Technology.
In addition to the press releases listed below, 28 new Chandra images
were posted to the chandra.harvard.edu website. Many of these have
been picked up various science or astronomy-oriented websites. For
the full list of Chandra images from this period, see
http://chandra.harvard.edu/photo/chronological.html
Swift is branching out. After major news stories in 2005 about GRBs,
Swift is gaining attention for ABGB news like comet and supernova
observations. The BBC covered the Swift analysis of the Comet Tempel
1 impact in April. By May, Swift was observing
73P/Schwassmann-Wachmann 3, which received coverage on Space.Com and
other websites. The February 18 burst ultimately led to four Nature
papers in August about what turned out to be a supernova "caught in
the act." A NASA-led telecon attempted to lasso all the results into
a cohesive story, and this led to broad coverage in newspapers such as
the New York Times, Washington Post and all that Reuters produced, in
magazines, and on websites worldwide such as BBC and CNN.
Stefan Immler's HEAD press conference on supernova "mugshots"
(October) led to respectable coverage on the web, a full-page article
in Science, and a lengthy article in Der Speigel so far. The HEAD
press conferences on Swift's black hole census and jets received
considerable web coverage from Space.Com, Discovery Channel and
elsewhere, as well as articles in USA Today, Washington Times,
Christian Science Monitor, Science and Science News. The
Reeves-Fabian Suzaku HEAD press conference also made Science and USA
Today. Coverage from the HEAD meeting also included a release on M87
(Bill Forman et al.) that was reported in USA Today, Science Daily,
Xinhua (China) and Space.com.
Hot from the press:
Some pictures of the HEAD meeting are available at:
http://lheawww.gsfc.nasa.gov/users/imh/HEAD2006/
and
http://www.rxollc.com/windt/photos/20061006_SF/
Please send Ilana Harrus pictures of the meeting you would like to see
posted.
PBS aired the NOVA program "Monster of the Milky Way" about Sag A* on
October 31. This was a major team effort supported by the National
Science Foundation and the Gamma Ray Large Area Space Telescope, with
considerable legwork by Sonoma State University. The BBC World
Service visited NASA Goddard twice for separate programs on cosmology
and high-energy astronomy. This led to two 3-part radio programs by
different producers that featured high-energy astronomy prominently.
Korea Public Television also visited NASA Goddard for a two-part
program on Einstein, naturally featuring HEAD science.
And last but certainly not least! John Mather and George Smoot won
the 2006 Nobel Prize in Physics for their COBE work in the 1990s.
While not HEAD per se, this recognition of cosmological and
astrophysics research will raise the profile of HEAD science.
Naturally, this was the biggest astrophysics story of the year, with
over 500 Google news hits at one point in mid-October.
5. Chandra X-ray Observatory Operations Report--
Roger Brissenden, Smithsonian Astrophysical Observatory
and Martin Weisskopf, Marshall Space Flight Center
Chandra's excellent spacecraft and science instrument performance
continued during the last six months. The mission passed its 7 year
milestone on July 23 and retains significant reserves of
consumables. There were no major anomalies or safemodes during the
period, the last safe mode being 6.3 years ago.
The average observing efficiency since May was 67% compared with a
maximum possible of ~70%, up from 63% during the prior 6 months. The
increase is in large part due to the relaxation of a thermal
constraint associated with the EPHIN (Electron Proton Helium
Instrument) radiation detector. As discussed in the last report, the
maximum allowed temperature limit was raised from 96 deg F to 110 deg
F in December and, as expected, has provided much welcome relief to
the mission planning team.
Two flight software patches were uplinked in July to add on-board
monitoring of selected propulsion line and valve temperatures. The
patches added a new monitor and replaced 21 of the Liquid Apogee
Engine temperature readings (unused since the ascent phase of the
mission with 21 -Z side propulsion line and valve
temperatures. Chandra has experienced decreased thermal margins as the
mission has proceeded and the new on-board monitor mitigates the risk
of a frozen propulsion line by ensuring a transition to normal sun
mode in the event that temperatures fall below a safe trigger
threshold.
In other operational highlights, Chandra completed the 2006 summer
eclipse season in July with nominal power and thermal
performance. Chandra also passed though two lunar eclipses without
incident, a penumbral eclipse in August and a full eclipse lasting 20
minutes in October. The aspect camera continued its excellent
performance, with dark current measurements indicating a continued
expected trend in increase of the number of warm pixels. There were no
interruptions to the mission schedule due to high solar activity and
the schedule was replanned five times to accommodate fast turn-around
Target of Opportunity (TOO) observations, with response times ranging
from 1 to 3 days.
Both the ACIS and HRC focal plane instruments have continued to
operate well.
A test was conducted in August of the HRC +Y shutter select
function. During the test, three select/de-select cycles were run and
confirmed full functionality of the relay. The test verified that
after two years without use the +Y shutter has not been impacted by
the same failure mode as the -Y shutter. The -Y shutter did not insert
during an attempted observation in 2004, due a failed motor-select
relay.
As a result of increasing thermal trends associated with the ACIS
electronics, the ACIS team has recommended having the option of
selecting the minimum number of chips for a given observation in order
to reduce the instrument temperature. A reduction in temperature of
2.5 deg F is expected for each chip powered down.
The Charge Transfer Inefficiency (CTI) of the ACIS Front Illuminated
CCD has continued to increase at the expected rate of 2.3% per year
and the trend for the Back Illuminated CCD has continued at the
expected rate of 0.5% per year. Careful monitoring of the
contamination buildup on the Optical Blocking Filer indicates that the
transmission at 0.7 keV has decreased by the expected ~1.0% over the
last year. No actions are required in response to these trends. In
addition, the ACIS team completed the implementation of more accurate
on-board energy filters, and of a serial CTI correction.
The processing, archiving and distribution of Chandra data has
continued smoothly, and the average time from target observation to
data distribution has been maintained at approximately one day. The
archive has grown more rapidly in recent months due to the third full
reprocessing of Chandra data, and is now 5.3 TB in size. Data
retrievals have also increased from ~300 GB to 430 GB per month. The
third reprocessing is proceeding well and is now 60% complete with
completion expected in spring 2007.
The Operations Control Center ground team completed the development
and installation of a patch release (version 11.5.3) and a major
release (version 11.6) of the planning and scheduling system (Off-Line
System). The new releases fix a number of problems, upgrade
capabilities, particularly for plotting and parameter handling, and
provide new functionality for scheduling moving objects and handling
radiation events. The ground team also completed the installation and
testing of a new voice system.
The Science Data System team released versions 7.6.8 and 7.6.9 of the
CXC Data System to perform a software infrastructure upgrade, and to
provide functionality in support of selectively powering the ACIS
chips.
The Chandra Press Office issued 8 press releases and 21 image releases
since May, including NASA media telecons in June and August. One media
telecon described observations of the galactic black hole system GRO
J1655-40 that provide insight into the key role magnetic fields play
in the energy release mechanism. The second discussed observations of
the galaxy cluster 1E 0657-56 that provide direct evidence for dark
matter.
The Cycle 8 peer review was held in Boston in June and selected 184
proposals from 724 submitted for what will be an exciting and high
quality science program for the next year. This year, 9 proposals were
approved via joint facilities. The 2006 Chandra Fellows Symposium was
held at CfA in October and showcased the varied and cutting edge
research being conducted by the present Fellows. The Cycle 10 call for
Fellows will be made November 2. The CXC co-sponsored the successful
Joint Observatories Workshop held in Pasadena in May and will host the
Extragalactic Surveys workshop, November 6-8 (for details see
http://cxc.harvard.edu/xsurveys06/
We look forward to continued outstanding science from Chandra as we
progress into the 8th year of scientific operations.
The Chandra Postdoctoral Fellowship Program -- Nancy Remage Evans --
-- (CfA)
During the fall, the Chandra Fellowship program has two main
activities, the Chandra Fellows Symposium and the competition for
the Fellows for 2007.
--The Chandra Fellows Symposium was held at Harvard-Smithsonian
Center for Astrophysics on October 13, 2006. All the current Fellows
gave summaries of their work, which provide a very exciting
look on Chandra science. Keep this event in mind for future
years. It is open to all interested people. The program for
this year is shown below.
--The Chandra Fellowship competition for 2007 closed Nov. 2, 2006.
The new group of Fellows will be announced in February, 2007.
Details of the next competition will be posted at:
http://cxc.harvard.edu/fellows/ in the summer of 2007.
CHANDRA FELLOWS SYMPOSIUM
October 13, 2006
Phillips Auditorium, Harvard-Smithsonian Center for
Astrophysics
9:00 - 9:20 Welcome
9:20 - 9:40 Jan-Uwe Ness The 6th Outburst of the Recurrent
Nova RS Oph in X-rays
9:40 - 10:00 Masahiro Tsujimoto Joint Chandra and Suzaku
Spectroscopy of the Arches cluster
10:00 - 10:20 Carlos Badenes Opening a New Window onto the Physics
of Type Ia Supernovae
10:20 - 10:40 Franz Bauer Did We Miss a Local Supernova?
11:00 - 11:20 Shane Davis Probing Accretion and Spacetime with
Spectra of Black Hole Binaries
11:20 - 11:40 Elena Gallo Jets from Quiescent Stellar Mass Black Holes
11:40 - 12:00 Jifeng Liu Understanding the Nature of
Ultra-Luminous X-ray Sources
12:00 - 12:20 Elena Rossi Vertical Nuclear Profile of Hyper-accreting Disks
2:00 - 2:40 p.m. William Forman Shocks, Bubbles, and Filaments: the
Interaction of Supermassive Black Holes with Cluster Environments
2:40 - 3:00 Weiqun Zhang Numerical Studies of GRB Afterglows
3:00 - 3:20 Doron Chelouche The Gaseous Halos of Galaxies and Quasars
3:40 - 4:00 Elena Rasia Observing Galaxy Cluster Simulations
with an X-ray Telescope
4:00 - 4:20 Benjamin Maughan Chandra Observations of the Galaxy
Cluster Scaling Relations
4:20 - 4:40 David Sand Galaxy Cluster Supernovae at 0.1 < Z < 0.2
Back to Top
6. XMM-Newton Mission News - Randall Smith (NASA/GSFC) and
Phil Plait (Sonoma State)
The satellite and all instruments remain in good health, and the
operations team is maintaining a high observing efficiency with ~73%
of available time used for science observations. A major new release
(7.0.0) of the Science Analysis Software was released on June 30th,
2006, which includes a significant calibration improvements for all
instruments and is recommended for all users.
XMM-Newton closed its sixth Announcement of Opportunity on October
6th, 2006. A total of 594 proposals were received from 425 different
investigators, for a total over-subscription factor of 6.9. We
encourage investigators interested in extremely long or otherwise
unusual proposals to consider attending the XMM-Newton Legacy Projects
Workshop will be held June 4-6, 2007 at the XMM-Newton Science
Observations Center near Madrid, Spain. The goal of the workshop is
to identify the leading scientific and technical opportunities for
legacy projects of XMM-Newton, while may require large amounts of
observing time on one or more targets. For more information, see
http://xmm.vilspa.esa.es/external/xmm_science/workshops/2007_science/
Recent accomplishments include two notable results on supernova
remnants. Jacco Vink (University of Utrecht) and collaborators
published an analysis of XMM-Newton and Chandra observations of RCW
86, showing that it is likely the same supernova seen by Chinese
astronomers in 185 AD. Meanwhile, Andrea De Luca (IASF/INAF) and
collaborators discovered that the central neutron star in RCW103
(1E16348-5055) exhibits an curiously long 6.7 hour period. If this is
an orbital period, the system is perhaps the youngest low-mass X-ray
binary known (the remnant is only 2000 years old) while if the period
is due to rotation it would require some never-before-seen method to
slow the spin of the young neutron star.
For more information about XMM-Newton, please visit the US Guest
Observer Facility pages at
http://heasarc.gsfc.nasa.gov/docs/xmm/xmmgof.html
XMM-Newton E/PO News:
The XMM-Newton E/PO group has created the Supernovas Educators Guide
with additional support from GLAST. This guide has three activities
which reflect different aspects of a supernova. The guide also
includes an introduction to the history of supernova astronomy and why
stars explode, and a beautifully illustrated poster with an artist's
conception of a supernova as seen in visible, X-rays, and gamma rays,
as well as a timeline illustrating a supernova remnant's
evolution. This guide is currently undergoing testing, with aspects
presented at two different workshops.
The XMM-Newton E/PO group sponsors Space Place to write articles about
XMM science. They recently published two articles written by Dr. Tony
Phillips: "Brush your teeth and avoid black holes?" about how
astronomers observe X-rays and "Not a Moment Wasted" about
XMM-Newton's slew survey. The first was sent to newspapers, and the
second as part of a newsletter sent to astronomy clubs.
The SSU E/PO group has also begun working with the Astronomical
Society of the Pacific's (ASP) Night Sky Network to create a kit
containing a series of activities based on high-energy
astronomy. GLAST and Swift are sponsoring this along with XMM-Newton,
as well as Suzaku. The SSU staff, with Jim Lochner, Beth Barbier, and
Sara Mitchell from the GSFC-based Suzaku E/PO team, met with NSN
personnel at the annual ASP meeting to go over possible topics for the
new kit.
Since April 2006 (the last newsletter), XMM-Newton Educator
Ambassadors and E/PO professionals disseminated educational materials
and XMM-Newton content at five different workshops, reaching 178
participants.
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7. INTEGRAL News - Christoph Winkler
INTEGRAL is continuing to work smoothly and to produce interesting
results. The space-craft and the instruments function well and the
ground segment operates routinely. The publication rate keeps
increasing with more than 196 papers published in refereed journals up
to the end of June 2006.
The 4th Announcement of Opportunity (AO-4) for INTEGRAL observations
was very successful with an over-subscription factor of 8 and a 31%
increase in the number of proposals compared to AO-3, largely due to
the inclusion of a prototype Key Programme on the Galactic Centre
region. At the time of writing the first observations of AO-4 have
been done, including already the first TOO (EXO 2030+375)!
From July 2 to 8 more than 200 participants from European countries,
the USA, Russia and Japan enjoyed a lively workshop and the
hos-pitality of our Russian colleagues at the Space Research Institute
(IKI) in Moscow. The theme this time was "The Obscured Universe". The
workshop was jointly co-sponsored by IKI (Space Research Insti-tute),
ESA (European Space Agency), RAS (Russian Academy of Sciences) and
RFBR (Russian Foundation for Basic Research).
For more INTEGRAL news, please see the INTEGRAL Newsletters at
http://integral.esac.esa.int//newsletters/
Back to Top
8. RHESSI Mission News - David M. Smith, U. C. Santa Cruz
The Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI)
continues to observe flares and microflares from the Sun even in the
current solar minimum. Although the rear segments of its germanium
detectors are suffering badly from radiation damage, the front
segments continue to have excellent resolution at low energies (below
100 keV), and the entire detectors can still be used for continuum
work. Annealing of the detectors to improve energy resolution will
take place before the next solar maximum, but is not scheduled for the
near future due to the excellent continuing performance of the front
segments.
RHESSI has been functioning as part of the Interplanetary Network to
localize cosmic gamma-ray bursts (GRBs) for some time now, in an
effort led by Kevin Hurley of the University of California, Berkeley
(UCB). Recently, a larger team at the Paul Scherrer Institute
(Switzerland) and UCB has begun providing spectral fits to GRBs from
RHESSI within a few days of discovery, via the GCN circulars (Eric
Bellm et al., GCN 5418, 5685; Claudia Wigger et al., GCN 5725).
RHESSI can sometimes get a better value for the peak energy "Epeak" of
the GRB than other instruments, particularly for harder bursts (high
Epeak). Finding Epeak for a large sample of GRBs is useful both for
the modeling of GRB physics and for the effort to use GRBs as a
standard candle for cosmology.
Another successful offpointing campaign to the Crab Nebula took place
this June. We are also taking advantage of long periods with very low
solar activity to study the x-ray spectrum of the quiet Sun.
Assuming that the source is comparable in size to the solar disk, this
can be done by letting the Sun drift to the edge of the instrument's
field of view (about 1 degree off axis). In contrast to RHESSI's usual
bi-grid collimator imaging, which creates many rapid modulations per
spacecraft spin period, the offpointing lets each grid operate as a
simple rotating slat collimator, modulating the entire Sun twice per
spin. Little is known about what to expect from the quiet Sun: there
may be contributions from very low-level particle acceleration in the
corona, and there is certainly occultation of the cosmic diffuse
background (a negative contribution) and some x-rays related to cosmic
rays hitting the Sun (a positive contribution). The solar disk is
also a place to look for exotic, long-shot physics like axion
annihilation. You can read about this work, led by Dr. Iain Hannah of
UCB, at the following website:
http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=16
Other RHESSI science "nuggets" suitable for a general scientific
audience
can also be found there. Solar physics preprints, including many from
RHESSI, are available at:
http://solar.physics.montana.edu/cgi-bin/eprint/default_page.pl
RHESSI results will be presented in several sessions of the 2006 Fall
meeting of the American Geophysical Union in San Francisco.
Back to Top
9. Swift Mission News - Padi Boyd and Neil Gehrels (GSFC) and Phil Plait and
Lynn Cominsky (Sonoma State)
As of mid-October 2006, Swift has observed 185 gamma-ray bursts (GRBs)
and performed 177 rapid-reaction targets of opportunity for non-burst
transients. The instrument continues operating in good health.
Swift also continues to monitor the early light curves of nearby
supernovae, particularly in the UV, to investigate the existence of a
UV canonical light curve and search for early X-ray emission from the
events.
The BAT team has made light curves from their survey processing
available at
http://swift.gsfc.nasa.gov/docs/swift/results/transients/
The light
curves cover the time range September 2005 through the present and are
updated when new data are received from the spacecraft. Data for well
over 200 persistent and transient high energy sources are available.
The Swift team has recently begun to compile short reports on BAT, XRT
and UVOT observations of GRBs. They can be found at
http://gcn.gsfc.nasa.gov/report_archive.html
These reports summarize
the basic information from each instrument (position, duration,
fluxes, etc.) and include light curves from all three instruments.
The Swift Cycle 3 proposal review was held in San Francisco in early
October 2006. Scientists from around the world met to evaluate the 88
proposals submitted for funding and/or observing time. A new component
to Cycle 3 was limited Target Of Opportunity
proposals. This was the most popular component of the GI Program, and
a well-balanced program has been accepted. The results of the Swift
review should be communicated to PIs by NASA Headquarters in the near
future.
Look for information on Swift Cycle 4 to appear in the NASA Research
Opportunities in Space and Earth and Sciences (ROSES)-2007, due to
become public in late January 2007.
Swift E/PO News: The E/PO group has published the fifth quarterly
newsletter, designed to keep scientists and the public updated on the
latest Swift news. The newsletter opens with a note from PI Neil
Gehrels, and has updates on Swift science and educational products, as
well as links to news articles featuring Swift. The newsletter and
archives are online (in both HTML and PDF) at
http://swift.sonoma.edu/resources/multimedia/newsletter/index.html
The real-time all-sky GRB (
http://grb.sonoma.edu) page has had about 60,000 unique visits
since April 2006. The page displays all the GRBs detected by Swift,
INTEGRAL, and other gamma-ray satellites as they send out notices to
the Gamma-Ray Coordinates Network. In addition, we have created the
"GRB Lottery," where people can guess where the next GRB will
occur. The site -- http://swift.sonoma.edu/grb_lotto/ -- was created
by Swift E/PO team member Tim Graves, and has a very appealing and fun
interface.
The Swift E/PO group has updated the very popular Newton's Laws
posters. These posters, designed to illustrate the Three Laws of
Motion, went through thorough testing recently, and were improved
using those tests as guidelines. We also added a fourth poster,
covering the Universal Law of Gravitation. We are awaiting the final
assessment and professional overview of the posters from WestEd, our
external evaluators, before we can go through the final revision and
print the posters.
Swift information and E/PO goodies were distributed at the GLAST
exhibit booth which was sent to the October HEAD meeting in San
Francisco. E/PO staff Phil Plait and Sarah Silva also recorded
interviews with several GLAST and Swift team members which will be
edited and added to the websites as a semi-regular feature. We hope
that this will bring some of the excitement and human interest of
these missions to classrooms and the public.
Prof. Lynn Cominsky helped prepare two Swift press releases, which
were featured in press conferences at the HEAD meeting, in San
Francisco in October (see HEAD in the News for more information). A
NASA telecon about GRB060218 was held in August, with evidence from
Swift that a supernova was "caught in the act." Another press release
from Swift, featuring x-rays detected from a comet, also made news in
May. The planetarium show "Black Holes: The Other Side of Infinity,"
which features the Swift launch, is now playing at several venues
across the country. And the PBS NOVA show "Monster of the Milky Way"
includes footage of the Swift Mission Operations Center at Penn
State. (See the GLAST E/PO entry for more details about both of these
shows.)
Since May 2006 (the last HEAD newsletter), Swift Educator Ambassadors
and E/PO professionals disseminated educational materials and Swift
content at 15 different workshops, reaching 2836 participants.
Back to Top
10. RXTE News - Padi Boyd, Keith Jahoda, Craig Markwardt,
Gail Rohrbach, Evan Smith, Tod Strohmayer, and Jean Swank - GSFC
The Rossi X-Ray Timing Explorer (RXTE) has now passed its first decade
in orbit. RXTE continues to serve the astrophysics community, and to
produce important scientific results, some of the most recent of which
are highlighted below. RXTE's Cycle 11 observing program is currently
well underway.
NASA's 2006 Senior Review of the Astrophysics Division Mission
Operations and Data Analysis (MO&DA) Programs was held in April
2006. The panel found that "RXTE remains a valuable asset to NASA's
space science mission set. It continues to be productive, with
continuing substantial interest from the community." We are pleased to
report that the review panel recommended continuing RXTE operations
until February 2009. As a result of this late-breaking good news
about RXTE's future, an Announcement was released by NASA Headquarters
in late October, 2006, soliciting proposals for observations to be
carried out beginning about June 1, 2007. We would like to thank all
RXTE users and friends whose science results helped us make a strong
case for continuing the mission.
The Cycle 12 Announcement solicits proposals for observations
only. There is no Guest Observer funding to analyze Cycle 12
observations, however, observers with proposals accepted through the
Cycle 12 Announcement may submit funding proposals to the NASA
Astrophysics Data Program (ADP).
The Cycle 12 proposal due date is Friday, January 26, 2007. The peer
review will be held in the Baltimore area in early April 2007. Please
consider offering your services as a Peer Reviewer. Interested Ph.D.
scientists can be added to the reviewer pool by sending an email to
peer_review@olegacy.gsfc.nasa.gov. Since this may well be the last
call for RXTE proposals, we encourage all members of the HEAD
community to consider submitting an RXTE Cycle 12 observing proposal.
The policy of the RXTE guest observer program has been to complete
accepted observations to the best extent possible. Targets of
opportunity have often led to delay in carrying out other observations
that were not time critical. We hope that 2007 will be an opportunity
to successfully schedule some of these delayed observations. Details
of how to handle extension of monitoring programs and target of
opportunity proposals soon will be posted on the RXTE web site at
http://xte.gsfc.nasa.gov/docs/xte/xte_1st.html.
Science Highlights:
In one of the more imaginative uses of RXTE data that has ever come to
our attention, Hsiang-Kuang Chang (National Tsing Hua University,
Taiwan) and colleagues have discovered millisecond long dips in the
X-ray flux from Sco X-1 using RXTE's proportional counter array
(PCA). They found about 50 of these dips, each lasting several
milliseconds, in 320 ksecs of data on the source. They argue that the
dips are most likely produced by occultations of Sco X-1 by small (<
100 meters) trans-neptunian objects (TNOs) within our solar system.
Detecting such dips requires a high counting rate, hence their use of
Sco X-1 for this study. They suggest that the number of observed dips
is more or less consistent with an extrapolation of the size
distribution based on direct observations of larger objects. Details
of their study can be found in Nature, 442, 660-663 (10 August 2006).
Observations of Supernova 1987A with RXTE have not yet found a pulsar
in its remnant, but John Middleditch (LANL), Frank Marshall
(NASA/GSFC) and colleagues did locate another nearby pulsar, PSR
J0537-6910, that is still the fastest known rotation powered pulsar
(16 ms spin period). This pulsar is also the most prolific "glitcher"
known, and seven years of RXTE monitoring of the pulsar have yielded
some amazing findings. A total of 23 glitches have now been seen, and
a clear correlation has been found between the strength (amplitude) of
a glitch, and the time interval to the next glitch, such that after a
big glitch there is a longer waiting time to the next glitch. The
correlation is good enough that the date the next glitch will happen
can be predicted with an accuracy of a few days. The data suggest
that there is a maximum lag that can develop between the rotating
crust and its superfluid component. Details will appear in the
Astrophysical Journal, but presently can be found at
http://xxx.lanl.gov/abs/astro-ph/0605007
A pair of interesting results on accreting millisecond pulsars were
presented as side-by-side posters by Fotis Gavriil (NPP/GSFC) and
Miriam Krauss (MIT) at the recent HEAD meeting in San Francisco.
Gavriil and collaborators reported the discovery of a new, but
intermittent 442 Hz pulsar during RXTE observations of the Globular
Cluster NGC 6440. Pulsations were observed only once, for about 500
seconds following a drop in the X-ray flux which may have been the
decaying tail of an X-ray burst, or perhaps the precursor of a
"superburst." A small downward drift in the coherent pulsation was
also detected, but the pulsation died away before the end of the
observation. Krauss and colleagues reported on RXTE observations of
HETE J1900.1-2455, the 377 Hz accreting pulsar. They have found that,
unlike other accreting millisecond pulsars, the source has remained
active for more than a year, and, interestingly, the pulsations are
detected only intermittently, with abrupt increases in the pulsed
amplitude following thermonuclear bursts. The behavior of these two
objects may be related, and they could provide new insight as to why
the majority of accreting neutron star LMXBs do not show persistent
pulsations.
A number of accreting binary systems have been observed in outburst.
In June 2006 the Be/X-ray pulsar EXO 2030+375 started a large outburst
(type II) and reached a peak luminosity about 70% of that seen with
EXOSAT during the discovery outburst (Atels 843, 877). A joint
spectral analysis with PCA and HEXTE data required a Gaussian
absorption line at 10.1 keV, which can be ascribed to cyclotron
resonance absorption. Colleen Wilson-Hodge and Mark Finger (NSSTC)
also reported that strong spin-up was observed.
RXTE GOF Update:
New background models for RXTE PCA observations were recently made
available to the public. The new models have removed long term trends
that became apparent over the years (with magnitudes of ~0.2
ct/s/PCU). Only models for "Epoch 5" -- May 2000 to the present --
were changed.
The unmodeled variance in the background rate, which fundamentally
limits the sensitivity to source variations, is 0.04 ct/s/PCU or
better, in the top layer 2-10 keV band, and 0.02 ct/s/PCU in the top
layer 10-20 keV band. However, for purposes of determining absolute
fluxes of sources at arbitrary points on the sky, the cosmic X-ray
background is the limiting factor. The new background models can be
downloaded from the "PCA Digest page."
http://heasarc.gsfc.nasa.gov/docs/xte/pca_news.html
Earlier this year, HEXTE cluster A experienced more periods where on-
and off-source modulation (ie. rocking) ceased. Because of this the
decision was made to permanently leave HEXTE Cluster A in the
on-source position, rather than risk it becoming unrecoverable in an
off-source position. The detectors in cluster A are still functioning
well; HEXTE cluster B also still modulates as normal, and shows no
sign of impairment. The HEXTE team has delivered new software that
will allow users to generate cluster A background estimates from
simultaneous cluster B background files (see Katja Pottschmidt's HEAD
poster about hextebackest at
http://heasarc.gsfc.nasa.gov/docs/xte/whatsnew/hextebackest_poster.pdf).
The RXTE GOF is now working to make this code available at the next
interim HEAsoft (FTOOLS) release, currently scheduled for late
November. Before analyzing any HEXTE A data taken in 2006, we
recommend users consult the RXTE "Significant Events" page
(http://heasarc.gsfc.nasa.gov/docs/xte/whatsnew/big.html) to see
whether HEXTE A was fixed or rocking when their data was collected.
When the HEAsoft release containing the new HEXTE tool is available,
an announcement will be sent to the XTENEWS mailing list, and will
also appear on the RXTE homepage
(
http://heasarc.gsfc.nasa.gov/docs/xte/xte_1st.html).
Back to Top
11. Suzaku News - Koji Mukai and Ilana Harrus (GSFC)
Suzaku Cycle 2 proposals are due on December 1, 2006 at ISAS/JAXA,
NASA/GSFC, or ESA, depending on the country in which the principal
investigator resides. US-based HEAD members are invited to visit the
Suzaku GOF page (
http://suzaku.gsfc.nasa.gov/ ) for further details.
ISAS/JAXA and NASA/GSFC have begun distribution of processed guest
observer (GO) data. Initial processing pipeline version 1.1; an
improved version (1.2) is now in place. We plan to reprocess all
data, including the Science Working Group (SWG) observations, using
v1.2 pipeline. In a related note, NASA has started distribution of
Suzaku grants for successful Cycle 1 proposers whose observations have
already been performed.
Both the XIS and the HXD continue to function well. The XIS team has
begun the use of "spaced-row Charge Injection" (CI). In-orbit
radiation damage has led to increasing charge transfer inefficiency
(CTI), which degrades the spectral resolution of the CCDs. Spaced-row
CI fills the charge traps with injected charge, thereby dramatically
reducing the CTI. With CI, the spectral resolution in the Fe K band
recovers almost to the immediate post-launch level. The XIS team has
begun to offer CI as an option to Cycle 1 GOs; this will be the
default for Cycle 2 observations.
Members of the Suzaku SWG have been busy analyzing the early data,
from which 2 refereed papers have already appeared in ApJ Letters
(Murashima et al. 2006, ApJ 647, 131L and Terada et al. 2006, ApJ 648,
139L). A special issue of Publications of the Astronomical Society of
Japan is in press, containing 30 papers (including the spacecraft and
instrument papers). The issue should have a 2006 publication date; in
the mean time, many of these papers have already appeared on astro-ph.
At the recent HEAD meeting, there were several presentations featuring
Suzaku data. In addition, ISAS/JAXA prepared a CD-ROM containing the
ApJ and PASJ papers; all 100 copies were "sold out" within the first
couple of days of the meeting.
Reminder: Suzaku Cycle 2 observing proposals are due on Dec 1, 2006.
The AO-2 version of the Suzaku Technical Description document is now
online. Response files for simulation and related tools have also
been updated for AO-2 proposers.
Please note that, although a version of the Technical Description
document was made available on Oct 28, some important XIS
updates were inadvertently left off at the time. Please refer
to the new version (GSFC version was updated Monday afternoon;
ISAS version Tuesday morning). Please see
http://suzaku.gsfc.nasa.gov/docs/suzaku/aehp_prop_tools.html
Suzaku EPO News:
The Suzaku EPO team is on its way to Hollywood! Well, maybe not that
far, but still. The team received the 2006 Silver Telly Award for the
video called "Building the Coolest X-ray Satellite" telling the story
of the building of the XRT and XRS on-board Suzaku.
If you don't have your very own copy, ask for it at your local video
store or at:
http://suzaku-epo.gsfc.nasa.gov/cgi-bin/astroe_lc/order.pl
Encouraged by the result of their first foray in the "Seventh Art",
the team is preparing another video on spectroscopy and music.
Production is very hush-hush but the schedule calls for a release in
time for the Oscar ceremony.
We are also currently planning a Night Sky Network kit in
collaboration with Sarah Silva, Lynn Cominsky, Phil Plait, and Logan
Hill at Sonoma State University and the Astronomical Society of the
Pacific. The kit, featuring activities conceived for the amateur
astronomer community, will be ready for release early 2008.
Back to Top
12. GLAST Mission News - Christopher Wanjek, Steven Ritz
and Phil Plait
All the major components of GLAST are now at General Dynamics C4
Systems (Spectrum Astro) in Scottsdale, Ariz., undergoing final
assembly. The GLAST Burst Monitor arrived in July, after successful
environmental testing at Marshall Space Flight Center. The Large Area
Telescope (LAT) arrived in September. In May, LAT had shipped from
SLAC to the U.S. Naval Research Laboratory in Washington for
environmental testing, which was completed on schedule. From NRL, LAT
was trucked back across the country to Arizona. After both
instruments are integrated onto the spacecraft, GLAST will travel back
east once again, to the NASA Kennedy Space Center for launch in fall
2007. A beam test of LAT hardware was completed at CERN in September.
The very successful GLAST Data Challenge II ran from March to early
June. As reported in the previous HEAD news, the goal of this game
was to detect the gamma-ray sources planted in simulated data that
look very much like what is expected to be seen once GLAST is in
orbit. More than 100 scientists participated, and the closeout
meeting, where the "truth" was revealed, was held at Goddard. Data
challenges are becoming common practice for large particle physics
experiments; they are new to astrophysics experiments, but beneficial
for any mission to test data processing and analysis software
end-to-end before launch. The GLAST Users Committee will do a beta
test of the analysis tools in November.
The First International GLAST Symposium will be held on 5-8 February
2007 at Stanford. Please visit the conference website at
http://glast.gsfc.nasa.gov/science/symposium/2007/
and register.
We are starting a monthly GLAST news email list. To sign up, please
send an email to majordomo@athena.gsfc.nasa.gov (you can leave the
subject line blank); in the body of the message, please write the
following: subscribe glastnews your-email-address
Back to Top
13. Constellation X Mission Update - Michael Garcia for the
Con-X Team
In our last newsletter article, we mentioned that the FY07 budget was difficult
for all of the NASA Science Mission Directorate, ConX included.
Several projects were canceled outright. ConX did well in comparison
by suffering only a 50% budget cut just mid-way through the fiscal
year, but in the words of the 2007 budget request was 'deferred
indefinitely' The entire Beyond Einstein program suffered similarly
difficult cuts and delays. Simply delaying a mission increases its
cost due to inflation, and multi-year delays can result in substantial
increases in projected costs.
In this climate, it was clear that the ConX team would do well to
continue to look into ways to reduce the cost of the mission. Having
recently moved from a 4 spacecraft configuration utilizing 2 Atlas V
launchers to a single spacecraft utilizing a single Delta IV Heavy
launcher and thereby saving $180M, we investigated even less
expensive launch options.
We found that we could fit 4 (somewhat smaller) Spectroscopy X-ray
Telescopes into a single Atlas V. To maintain effective area and to
lift the payload to L2 on the single Atlas V required
removing the 12 Hard X-ray Telescopes and the Reflection Grating
Spectrometer. The resulting configuration reduces costs by $700M,
meets the effective area requirements at our reference energies of
0.25, 1.25, and 6 keV and has reasonable effective area out to ~15keV.
In order to retain all of the key science objectives as outlined in
the last Decadal and detailed on the Con-X web site, this
configuration includes a Science Enhancement Package (SEP) which will
increase the spectral resolution at low energies and/or the effective
area at high energies. The details of the SEP are currently being
worked. A Request for Information about SEP options was released on
Oct 17 2006.
Details of this new 'Atlas V Configuration' were presented at the
recent HEAD meeting in San Francisco. This was the largest HEAD
meeting ever, and the Constellation-X talks were very well attended.
You can find the talks by Harvey Tananbaum, Ann Hornschemeier, and
Nick White on the Con-X home page (right hand column) at
http://constellation.gsfc.nasa.gov/.
In parallel with the definition of the SEP, the Constellation-X team
is preparing for a review which NASA and DOE have asked the National
Research Council(NRC) to undertake. The NRC will review the 5 Beyond
Einstein(BE) missions and recommend which should go first. This
review will also provide input which NASA could use for future
decisions regarding the support and sequencing of the other BE
missions pending inputs from the next Decadal Survey.
Inputs to this review are expected to be provided soon, no later than
Jan 2007. Your help in preparing for this review is invited! Several
teams are already working on updates to the science case. These teams
are loosely based on those which helped produce the May 2005 'Science
with Constellation-X' Booklet, and many of them met at the recent HEAD
meeting. If you wish to contribute please contact Michael Garcia or
Ann Hornschemeier.
There will be an open meeting of the Constellation-X Facility Science
Team (FST) from Dec 18-20 at GSFC. The agenda for this meeting will
include discussion of the SEP, the Atlas V configuration, and the
science case to be presented to the NRC Review Committee. You are
invited to attend, but please be advised that the meeting will take
place on the GSFC base and therefore ID Badges will be needed. For
details see the Constellation-X home page, and keep in mind that the
deadline for requesting badges is Dec 11 for US citizens and more than
1 month earlier for non-US citizens.
Back to Top
14. LISA Mission Update - Bonny Schumaker, JPL
LISA is a unique facility for astronomy and physics that will open a
huge discovery space unreachable from ground and untapped by other
space missions. It will detect and measure the properties of
gravitational waves over a broad band at low frequencies, from 0.1-100
milliHz. This will offer the opportunity to study a wide range of
sources that are "dark" electromagnetically: massive black holes
merging in galaxies at all distances; massive black holes consuming
smaller compact objects; non-interacting binary compact stars and
stellar remnants; and other less predictable sources such as
relics of the extremely early big bang. Many LISA sources will
also have electromagnetic counterparts, at a variety of timescales
and measurement frequencies. For example, known optical binaries
will be used to verify LISA's operation during initial on-orbit
commissioning; and many other of LISA's white-dwarf binaries will
be observable by tidal heating and eclipses. Black hole mergers
with accompanying disruption of their innermost accretion disks
may display non-thermal radiation from radio to gamma rays; and
compact objects falling into larger black holes may radiate
electromagnetically as debris is stripped from them.
These signals convey rich information addressing a wide range of
science: the history of galaxies and black holes in the universe;
General Relativity and the behavior of spacetime; precision
measurements of the Universe on a cosmic scale; the physics of dense
matter and stellar remnants; and possibly new physics associated with
events in the early Universe or relics predicted by string theory.
LISA's science can be summarized briefly by the following goals and
their ramifications:
1) Record the inspirals and mergers of binary black holes. This will
provide a precise mathematical understanding of the most powerful
transformations of energy in the Universe, and a rich testbed for
General Relativity.
2) Map isolated black holes with high precision, and verify that they
are the stationary "no-hair" spacetimes described by the Kerr metric -
i.e., specified completely by their mass and three components of
spin. This information will come from black hole mergers and from the
"Extreme Mass Ratio Inspirals" (EMRIs) involving compact objects such
as degenerate dwarfs, neutron stars, or stellar-mass black holes.
3) Observe directly the formation, growth, and interactions of massive
black holes over the entire history of galaxy formation. The Universe
accessible to LISA contains so many galaxies in their formation stage
that mergers happen quite frequently. Indeed, if the massive black
holes inferred to be at the centers of most galaxies formed primarily
by this process, LISA will detect a merger event once or twice per
week, from a wide range of redshifts extending back to early
protogalaxies at z~15.
4) Measure precise, gravitationally-calibrated absolute distances to
very high redshift. This will offer a unique contribution to
measurement of the Hubble constant and Dark Energy. It is achievable
because the inspiral leading to merger of black holes generates
gravitational waves that can be computed exactly in General
Relativity, so that the masses, spins, orientations, and exact
distance can all be reconstructed from the LISA data, over a wide
range of redshift. If an electromagnetic counterpart can be
identified to provide an independent redshift, then in the absence of
propagation effects the absolute physical distance can be estimated to
better than 1% precision.
5) Measure the 3D positions and orbital properties of thousands of
compact binary stars in our Galaxy. This will provide a new window
into matter at the extreme endpoints of stellar evolution, detailed
mapping and reconstruction of the history of stars in our Galaxy, and
insight into tidal and other non-gravitational influences on orbits
that reflect internal physics of the compact remnants. These are
among the "guaranteed" LISA sources - some of them, with already-known
positions and periods, will be used during on-orbit commissioning to
verify LISA?s operation.
Finally, given that all forms of mass and energy couple to gravity and
that LISA will probe to very high redshift, we can expect to discover
new phenomena not detectable with instruments that measure particles
and fields. The LISA band in the relativistic early Universe is the
Terascale frontier, where phase transitions of new forces of nature or
extra dimensions of space might have caused catastrophic, explosive
bubble growth and efficient (>10^-7) radiation of gravitational waves,
producing a background visible to LISA between about 100GeV and
1000TeV. LISA will also probe new forms of energy, such as
superstrings (relics of the early Universe), visible only by the
gravitational waves they emit. Their signature could provide direct
evidence that all forms of matter and energy, even spacetime itself,
are made of quantum strings.
LISA Mission Overview
LISA uses three identical spacecraft whose relative positions mark the
vertices of an equilateral triangle five million km on a side, in
orbit around the Sun. It can be thought of as a giant Michelson
interferometer in space, with a third arm that provides independent
information on the two gravitational wave polarizations as well as
redundancy. The spacecraft separation - 5Mkm - sets the LISA
measurement band. The centre of the LISA triangle traces an orbit in
the ecliptic plane, 1AU from the Sun and 20 degrees behind Earth, and
the plane of the triangle is inclined at 60 degrees to the ecliptic
(see Figures 1 and 2) . The triangular formation is maintained
throughout the year, with the triangle appearing to rotate about its
center once per year.
The actual implementation more resembles spacecraft radio Doppler
tracking, but with infrared laser light. Laser light received from
the distant spacecraft is phase-locked to a local laser and
transmitted (transponded) back, where it is combined in a standard
heterodyne detection scheme with a portion of the original laser
light. The use of two arms is essential for immunity to laser
frequency fluctuations. But because orbital mechanics prohibits
keeping the arms sufficiently equal in length, LISA uses a two-fold
approach to synthesize an equal-arm Michelson. First, each laser is
pre-stabilized to an optical cavity, and further stabilized to the
LISA arms themselves by a technique called "direct arm-locking."
Second, any residual laser frequency noise in the measurements is
removed by a processing technique called Time Delay Interferometry
(TDI).
Each spacecraft contains a pair of optical assemblies oriented at
roughly 60 degrees to each other. Each assembly is pointing toward a
similar one on the corresponding distant spacecraft, to form a
(non-orthogonal) Michelson interferometer. Through a 40-cm aperture
telescope on each assembly, a laser beam from a Nd:YAG master
laser and 2-W Yb:YAG fiber amplifier is transmitted to the
corresponding remote spacecraft. The same telescope is used to
collect the very weak incoming beam (around 100 pW) from the distant
spacecraft and direct it to a sensitive photodetector, where it is
combined with a local-oscillator beam derived from the original local
laser light. At the heart of each assembly is a vacuum enclosure
containing a free-flying polished platinum-gold cube, 4 cm in size -
the "proof mass," which serves as an inertial reference for the local
optical assembly. A passing gravitational wave
will produce a relative strain in this large "optical truss" causing
an increase in the optical path length between proof masses forming
one arm while causing a decrease for the other arm. These length
changes are measured interferometrically with sub-Angstrom precision.
In this way, LISA will be sensitive enough to detect
gravitational-wave induced strains of amplitude h=?l/l ~ 10-23 in one
year of observation, with a signal-to-noise ratio of 5.
The spacecraft surrounding each pair of optical assemblies serves
primarily to shield the proof masses from the adverse effects of solar
radiation pressure fluctuations; the spacecraft positions do not enter
directly into the measurements. Nevertheless, in order to minimize
disturbances to the proof masses from fluctuating forces in their
vicinities, each spacecraft must be kept moderately centered around
the proof masses (to about 10 nm/Hz in the measurement band). This
is achieved by a "drag-free" control system based on small electric
thrusters and displacement sensors. Specifically, both capacitive and
optical sensors are used to measure the displacements and rotations of
the proof masses relative to the spacecraft. These offset signals are
then fed back to control micro-Newton thrusters, which force the
spacecraft to follow its proof masses. The thrusters are also used to
control the attitude of the spacecraft relative to the incoming
optical wavefronts, using signals derived from quadrant
photodiodes. Capacitive actuation is used to adjust the positions or
orientations of the proof masses when needed.
LISA Programmatics
The LISA Mission is based on a strong partnership between NASA and
ESA. Since the formal agreement was signed over two years ago, the
two agencies have worked very closely as a single virtual team to
develop the technologies and the mission architecture. The
formulation phase began formally in January 2005. The Mission
Architecture Review took place in October 2005 and Mid-term review
this past spring. An independent technology review held last spring
concluded that the mission's technology requirements are well
understand and the plans for completing development of the critical
technologies are sound.
LISA's launch will be preceded by the LISA Path Finder (LPF), a
technology demonstration mission managed by ESA which carries both ESA
and NASA test packages the LISA Test Package (LTP) and the Disturbance
Reduction System (DRS), respectively. These will prove LISA's
measurement principle and its key technologies in space. More
information at an introductory level can be found in issues of The
LISA Newsletter and other links at www.lisa-science.org, the internal
web portal for the LISA International Science Community.
Current LISA efforts are focused in three areas: Science capability,
Technology maturity, and Total mission cost. The science case for
LISA has been developed extensively and continues to grow in depth and
clarity. Data analysis methods are being developed to ensure that we
will be ready to identify sources (individual and background),
including techniques to pull signals out of background noise
(including source noise, such as the sea of galactic white-dwarf
binaries) and numerical relativity breakthroughs to predict waveforms
for the inspiral, merger, and ringdown phases of massive black hole
mergers. A strong case is growing to prove that the science proposed
by LISA is doable and the science requirements well understood.
As noted above, a recent independent review of technology development
program concluded that LISA is well on its way to completing
development of the critical technologies. Several key technology
efforts are summarized in the first and second issues of The LISA
Newsletter.
Mission cost is currently being probed at a new level of granularity,
in order to be ready to exercise a price-H-type model to verify
credibility of the estimates. This has only been possible as the
point design of the architecture has become clearer. A costing tool
is under development that will accommodate the various design trade
studies that remain.
Even science return has begun to be quantified to give formulae for
scientific value in terms of factors such as number of resolvable
sources we can expect to detect, intrinsic scientific interest of each
type of source, and how these relate to mission lifetime. Ultimately,
these relations among scientific value, mission life, and instrument
sensitivity will be convolved with analogous relations derived by
system engineering for mission cost, with the resulting ability to
answer questions such as "What mission life time maximizes scientific
value per dollar?" These kinds of studies are needed to ensure that
the mission design is scalable, allowing cost to be reduced if
required, with a clear understanding of the impact on the science
return.
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14. Meeting Announcements - a partial list!
Editor's note: A list of international astronomical meetings can be
found at
http://cadcwww.dao.nrc.ca/meetings/meetings.html
Below are listed meetings that may be of interest to HEAD members, and
particularly those where the meeting organizers have asked to have
their meeting announcement included in the HEAD newsletter.
"TEXAS IN AUSTRALIA" 23rd Texas Symposium on
Relativistic Astrophysics, Melbourne, Australia
11-15 December 2006
for more information, please see www.texas06.com
The First GLAST Symposium, Stanford University, CA, USA
5 -8 February, 2007
This is the first meeting in the series of International GLAST
Symposia. The Gamma-ray Large Area Space Telescope, GLAST, is a
mission to discover and study cosmic gamma-ray sources in the energy
range 20 MeV to >300 GeV, with supporting measurements for gamma-ray
bursts from 10 keV to 25 MeV. With its launch in Fall 2007, GLAST will
open a new and important window on a wide variety of high-energy
phenomena, including black holes and active galactic nuclei; gamma-ray
bursts; pulsars; the origin of cosmic rays and their relation to
supernova remnants; probes of the optical-UV EBL; new source classes;
solar physics; and searches for signals of hypothetical new phenomena
such as particle dark matter annihilations, extra dimensions, Lorentz
invariance violation, and other relics from the Big Bang. The first
Guest Investigator Cycle will start in 2007, with proposals due soon
after the Symposium. More information about the mission can be found
at http://glast.gsfc.nasa.gov and at links therein. The first
Symposium will focus on the new scientific investigations enabled by
GLAST, mission and instrument characteristics, analysis tools and
opportunities for guest investigators, and coordinated observations
and analyses. It is expected that the second Symposium will occur
approximately 18 months later.
More information can be found at http://glast.gsfc.nasa.gov/science/symposium/2007/
"Clusters of Galaxies as Cosmological Probes"
Winter 2007 Aspen Astrophysics Conference, Aspen, Colorado 12-16 February, 2007
Contact Andrey Kravtsov, e-mail: andrey@oddjob.uchicago.edu
The Aspen Center for Physics website should be
consulted for details about Aspen. See
http://www.aspenphys.org/
The Next Decade of Gamma-Ray Burst Afterglows
-Amsterdam, The Netherlands 19-23 March 2007
Contact Ralph Wijers rwijers@science.uva.nl
Extragalactic Jets: Theory and Observation
from Radio to Gamma Rays--
Girdwood, Alaska, USA 21-24 May, 2007
This international meeting is intended to bring theorists and
experimentalists together to discuss the nature of extragalactic jets,
from parsec to kiloparsec scales. Special emphasis will be given to
the interaction of jets with their environment and to the insights
this interaction can provide. All wavelengths will be discussed. A
major goal of the workshop is to enhance communication and to further
collaboration in the field. To facilitate dialog, the conference will
be limited in size to 80 participants. More information at http://aftar.uaa.alaska.edu/jets2007/
Obscured AGN across Cosmic Time
Kloster Seeon, Bavaria, Germany 5-7 June 2007
Current deep surveys, notably in X-rays and the mid-IR, are making it
possible to carry out a census of essentially all the luminous AGN in
the universe. By penetrating the obscuration that, in Type II sources,
hides the nuclear regions in the UV to the near-IR spectrum, these new
surveys are finding the radio quiet counterparts of the powerful radio
galaxies.
The completion of such a census has substantial cosmological
significance since it will provide the foundation for identifying the
role of AGN feedback in the galaxy formation process. The Type II
sources are of particular value here since, by acting as their own
coronographs, they facilitate the study of the star formation activity
and the investigation of the correlated growth of the black hole and
the host galaxy.
While radio galaxies - which are being used to trace the massive
galaxy population at all epochs - have been studied intensively for
the past 40 years, their radio quiet counterparts beyond the local
universe are only now being discovered in substantial numbers. The
workshop aims to bring together the established radio galaxy community
with the students of the radio quiet sources and so help to elucidate
the effects of the (possibly) different host galaxies and environment
and those of the powerful radio jets. More information at
http://www.eso.org/gen-fac/meetings/agnii2007/
"X-ray surveys: Evolution of accretion, star-formation
and the large scale structure", Rodos island, Greece
2 - 6 July, 2007
Chandra and XMM-Newton extragalactic surveys have provided a wealth of
exciting discoveries in the past few years. The largest fraction of
the X-ray backgound has been resolved yielding the strongest
constraints yet on the accretion history of the Universe. XMM-Newton
systematically detects clusters of galaxies at high redshift providing
invaluable cosmological information. Parallel to the observational
constraints, theoretical modelling of cluster formation and evolution
has also seen tremendous progress in the past few years. At the same
time a large number of X-ray selected normal galaxies have been
detected in both deep fields and wide field bright surveys, helping us
to probe for the first time the star-formation rate and its evolution
in X-ray wavelengths. Large area contiguous surveys start to probe
the AGN clustering properties and their environment. The scope of the
meeting is to examine in detail such recent X-ray survey findings and
their cosmolog\ ical implications, paving the way for future X-ray
missions.
Additional information can be obtained at
email: xray07@astro.noa.gr or
www : www.astro.noa.gr/~xray07
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HEADNEWS, the electronic newsletter of the High Energy Astrophysics Division of the American Astronomical Society, is issued twice yearly by the HEAD Secretary-Treasurer. The HEAD Executive Committee Members are:
