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Wed Dec 14, 2005

MIRAX workshop, Brazil

In December I attended the MIRAX workshop at INPE in São José dos Campos, Brazil. This is a nice, small-scale mission to be launched in 2010/11 which will use the BeppoSAX flight spare WFC camera, as well as a wide-field hard X-ray detector to be built by UCSD. Lots of interesting talks about X-ray transients and the science you can do with dedicated, long-term monitoring. Amongst the current and past monitoring projects mentioned are

Observations of transient LMXB pulsars (PDF file)

Labels: 2005, /missions

Tue Nov 15, 2005

Korea | Sydney | 4U 1636-536

Sejong University, Seoul, KoreaA busy few weeks, with a trip to Seoul to attend the 7th Pacific Rim Conference on Stellar Astrophysics. I gave a talk (PDF file) on accretion-powered millisecond pulsars, highlighting the recent observations of the latest discovery, HETE J1900.1-2455. Returned via Sydney where I visited a collaborator at U. Sydney and caught up with friends and family.
In the meantime, the long awaited paper on the radius-expansion bursts from 4U 1636-536 was finally accepted. In a study of all the bursts observed by RXTE, we found a bimodal distribution of peak radius-expansion burst fluxes, separated by a factor of 1.7. This is exactly what you would expect if the fainter bursts reach the Eddington limit in an atmosphere containing hydrogen at approximately solar abundances, while the brighter bursts instead occur in a pure helium environment. It remains a mystery exactly how the accreted hydrogen is eliminated from the atmosphere in the brighter radius-expansion bursts.
Read the paper

Labels: 2005, /meetings

Mon Oct 10, 2005

Australia-Italy Workshop on GW Detection

The workshop, organised by the UWA Gravity Wave group, was held at the Gingin observatory site, home also to the Gravity Discovery Centre. Attendees included members of all the major interferometer groups around the world - LIGO, VIRGO, GEO and TAMA, as well as representatives of the Italian government (co-sponsors) and the WA Minister for Science and the Environment, Judy Edwards. It was a pretty technical meeting, a lot of it over my head, but I learned quite a bit about some of the details of interferometric GW detectors, as well as the current status and prospects for the detectors around the world. Although the proposed Australian instrument will not be as sensitive as LIGO, for example, it will play an important role in the worldwide effort because of it's southern location and the correspondingly maximal baseline with the US LIGO detectors.
Accreting Neutron Stars as Gravitational Wave Sources (PDF file)

Labels: 2005, /gravitational waves

Fri Sep 16, 2005

IGR J00291+5934 in the news

Maurizio Falanga (CEA), Chris Wanjek (NASA) and I prepared a press release (courtesy SpaceflightNow) following the acceptance of Maurizio's A&A paper. The release first appeared at ESA on 6th September 2005. See also Une étoile « cannibale » at CEA (French) and the more detailed Festin stellaire: un pulsar milliseconde s'échauffe et accélère at SAp (French)
Earlier post: New millisecond X-ray pulsar IGR J00291+5934

Labels: 2005, /press

Wed Jul 27, 2005

Texas in Australia 2006

The increasingly poorly-named Texas Symposium on Relativistic Astrophysics will be held in Melbourne between 11-15 December 2006. Program and attendees TBA, but keep your calendars clear!
Download the poster

Labels: 2005, /meetings

Mon Jul 11, 2005

Suzaku (aka ASTRO-EII) launched

Suzaku (aka ASTRO-EII) successfully entered its intended orbit early this morning (local time), according to a JAXA Press Release. All stations (Christmas island, Santiago, and Uchinoura) have confirmed detection of the signal indicating the satellite's separation from the launcher.
Suzaku, like ASCA, is the name of a legendary bird god. ASTRO-EII is the replacement for the unsuccessful ASTRO-E satellite, destroyed shortly following launch in Feburary 2000. ASTRO-EII will cover the energy range 0.2 - 600 keV with the three instruments, X-ray micro-calorimeter (X-ray Spectrometer; XRS), X-ray CCDs (X-ray Imaging Spectrometer; XIS), and the hard X-ray detector (HXD). The operational status will be confirmed in about 5 days. Congratulations JAXA!
UPDATE Unfortunately, the liquid helium for the cryogenically-cooled XRS unexpectedly evaporated during initial operations, rendering it useless. The active lifetime for this instrument was expected to be 2 years. The ASTRO-EII team are expected to announce a new call for proposals with the remaining science instruments in January.
See the Quicktime launch video
Astro-E2 Guest Observer Facility at HEASARC

Labels: 2005, /missions

Sun Jul 10, 2005

ASA 2005

The Astronomical Society of Australia just held its 2005 meeting in Sydney, which was a lot of fun. One of the highlights was the launch, and review discussion, of the NCA's Decadal Plan for the period 2006-15. I presented a talk on some millisecond pulsar work, as well as Jasmina's talk on G347.3-0.5 (she unfortunately couldn't attend).
Link to PDF file

Labels: 2005, /meetings

Sat Jun 11, 2005

Discovery of pulsations in the X-ray transient 4U 1901+03

Back in 2003 we made RXTE observations of a new outburst of an old transient last seen in the early '70s, 4U 1901+03. We found pulsations at 2.763 s and an almost-circular orbit with period 22.58 d. Like KS 1947+30, this likely Be-X-ray binary has a much smaller than expected eccentricity of 0.036, suggesting that the natal kick from the supernova explosion which formed the neutron star was unusually small.
Read the paper (accepted by ApJ)
See also ATel #121

Labels: 2005, /hmxbs

Wed Jun 01, 2005

AAS #206, Minneapolis MN

Greetings from the 206th AAS meeting, all this week in Minneapolis. I presented a talk in Special Session 17: Fundamental Physics with Millisecond Pulsars about the newest accretion-powered millisecond pulsar, IGR J00291+5934
Link to PDF file
I also mentioned the outburst history to date of SAX J1808.4-3658, and commented that we were overdue for the next one; two days later a new outburst was detected in the PCA bulge scans.

Labels: 2005, /pulsars

Fri May 06, 2005

Compact Stellar X-ray Sources

Cambridge University Press' upcoming book will almost certainly be a must for anyone interested in white dwarfs, neutron stars and black holes. In the meantime, here is the table of contents with links to preprint articles on arXiv.org

  1. Accreting Neutron Stars and Black Holes: A Decade of Discoveries by D. Psaltis
  2. A review of rapid X-ray variability in X-ray binaries by M. van der Klis
  3. New Views of Thermonuclear Bursts by T. Strohmayer and L. Bildsten
  4. Black Hole Binaries by J. E. McClintock and R. A. Remillard
  5. Optical, ultraviolet and infrared observations of X-ray binaries by P.A. Charles and M.J. Coe
  6. Fast X-ray transients and X-ray flashes by J. Heise and J. in 't Zand
  7. Isolated neutron stars by V. Kaspi, M. Roberts and A. Harding
  8. Globular Cluster X-ray Sources by F. Verbunt and W.H.G. Lewin
  9. Jets from X-ray binaries by R. Fender
  10. X-Rays from cataclysmic variables by E. Kuulkers, A. Norton, A. Schwope and B. Warner
  11. Super soft sources by P. Kahabka
  12. Compact Stellar X-ray Sources in Normal Galaxies by G. Fabbiano and N.E. White
  13. Accretion in compact binaries by A. King
  14. Soft gamma repeaters and anomalous X-ray pulsars: magnetar candidates by P. Woods and C. Thompson
  15. Cosmic Gamma-Ray Bursts, Their Afterglows, and Their Host Galaxies by K. Hurley, R. Sari and S. G. Djorgovski
  16. Formation and Evolution of Compact Stellar X-ray Sources by T. M. Tauris and E. van den Heuvel

Labels: 2005, /reference