New outburst of IGR J17473-2721

This system was discovered back in 2005, and was detected in outburst again this March. Since then, it's been observed by Swift, INTEGRAL and RXTE, and even SuperAGILE detected a thermonuclear burst (ATel #1445). Following reports of the bursting activity we triggered some observations with RXTE to search for burst oscillations; we caught some bursts, but no oscillations. Since then, public RXTE observations revealed kHz QPOs and radius expansion bursts, from which we estimated the distance (ATel #1651). Observations are continuing.
See also
INTEGRAL monitoring of IGR J17473-2721
Diego Altamirano's IGR J17473-2721 page
IGR J17473-2721 at SIMBAD

Burst catalog paper accepted

The burst catalog paper has just been accepted by ApJS! The referee report, by a team of referees, stretched to 11 pages; it took quite a while to address all the (generally constructive) criticisms. In addition, the authors, all at MIT when the project started, are now scattered to the four corners of the US (as well as Australia). The accepted version is (I think) a big improvement on the original, the extra time spent has really helped our understanding of the global burst properties. Check it out for yourself at astro-ph/0608259v2

Click here to read the abstract and download the full version, as well as data tables

US/Netherlands tour

I just got back from a very busy trip around the US, with a stop in Amsterdam on the way home. I presented a couple of posters at the AAS/High Energy Astrophysics Division Meeting in Los Angeles, and went on to visit Ed Brown at JINA, where I gave a lunch talk on the following Monday.

Then it was on to Boston for a brief visit to MIT to catch up with collaborators and friends, as well as a pilgrimage to Toscaninis (sadly the Harvard Square location has closed). After that I had a couple of nights in St. Louis for the APS meeting, and gave an invited talk on burst observations in a special session on the physics of X-ray bursts (L3).

Finally I headed home via Amsterdam for another invited talk at the Decade of Accreting Millisecond X-ray Pulsars workshop at UvA.

HEAD posters 1 2 (0.24/1.22 MB PDF)
APS talk (10.2 MB PPT)
AMSPs workshop talk (1.5 MB PPT)

Biases for neutron-star mass, radius and distance measurements

Our paper on the unusually low "touchdown" fluxes for radius-expansion bursts from high-inclination sources was just accepted by MNRAS. Usually the touchdown flux is thought to equal the Eddington flux, but we found that in sources that show X-ray dips — likely arising from structure at the edge of the accretion disk passing across the line of sight, implying that we see these systems almost edge-on — the touchdown flux could be less than half the maximum flux seen earlier in the same burst. The low touchdown fluxes also likely arise from interactions with the disk material, which have some implications for neutron-star distance (but not mass and radius) determination following the method of Özel (2006)

Read the paper (arxiv.org:0712.0412)