Swift follow-up observations of unclassified ASCA sources

Details Swift follow-up observations of unclassified ASCA sources Swift follow-up observations of unclassified ASCA sources

2011-12-16

arxiv.org/abs/1112.3965v2

Astronomy and Astrophysics

Astrophysics

High Energy Astrophysical Phenomena

14 pages, 7 figures, 7 tables. Accepted for publication in A&A without revision. Updated a few references

Scientific paper

We present Swift follow-up observations of a sample of 35 unclassified faint X-ray sources drawn from the ASCA Galactic centre and plane surveys. Our short pointed XRT observations allow detections down to a limiting 0.3-10 keV flux of ~1E-13 erg cm-2 s-1, which translates into a luminosity of ~1E33 erg s-1 for an assumed distance of D=8 kpc. The brightest source in our sample reaches a maximum 0.3-10 keV luminosity of ~2E36 (D/8kpc)^2 erg s-1 during our observations. We detect 16 (46%) of the ASCA sources with the XRT, while 19 were not detected during our program. Since we are probing the faint end of the ASCA source populations, we expect a large fraction of the non-detections to be due to the Eddington bias. This is strengthened by the fact that we find the observed XRT count rates to be predominantly lower than expected based on the reported ASCA intensities. Investigation of the ASCA properties and long-term X-ray variability leads us to conclude that the non-detections likely include two spurious ASCA detections and three objects that are variable or transient X-ray sources. For the 16 XRT-detected sources we obtain positional accuracies of ~2-4", which significantly improves upon their ASCA uncertainties of ~1'. We use the X-ray spectra and variability to characterise these objects. Most appear to be faint, persistent X-ray emitters that have highly absorbed spectra. Based on their X-ray properties we identify three accreting compact objects: one confirmed (AX J1754.2-2754) and one candidate (AX J1538.3-5541) X-ray binary, and one possible magnetically accreting white dwarf (AX J1620.1-5002). Furthermore, we use the improved positions of XRT-detected sources to search for counterparts in simultaneously obtained Swift/UVOT images and possible associations with cataloged sources at various wavelengths. This reveals three possible main sequence stars amongst our sample.

Affiliated with

Also associated with

No associations

Rating

Swift follow-up observations of unclassified ASCA sources does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Swift follow-up observations of unclassified ASCA sources, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Swift follow-up observations of unclassified ASCA sources will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-170764