A Catalog of Near-Infrared Variables in the Galactic Center Region
Abstract
More than 3000 low-luminosity X-ray sources (10^30-10^33 erg/s at 8 kpc) have been detected in a 17'x17' region around Sgr A*. The detail of their nature, which is still elusive, would bring new insights in the evolutionary history of accreting compact binaries and of the inner Galaxy. The high extinction towards the Galactic Center (Av>25) and the high stellar density are the main obstacles in the characterization of these X-ray sources.
We searched for near-infrared long term variables in the Galactic Center Region (GCR). We performed multi-epoch observations in the K-band using large ground-based telescopes. With ISPI (CTIO 4m), we observed every year in 2005-2009 a 10'x10' field down to the crowding limit (seeing of ∼0.8", K∼14). With PANIC (Magellan 6.5m), we obtained 3 sets of observations (2004, 2007, 2010) to map a similar region with higher angular resolution (seeing of 0.4-0.6", K∼15). The preliminary analysis revealed K-band variables in the ISPI dataset and variables from the PANIC images. About 50 variables are common to both lists. We estimated a boresight correction and constrained the accuracy of the astrometry to typical errors of 1.5" at 95%. We found a significant association of ∼10 of the ISPI variables (which generally show higher amplitude variation than the PANIC variables) with hard X-ray sources in the GCR. We detect a PANIC variable star (K=13.6, dK=0.4) aligned with the low mass X-ray binary AX J1745.6-2901. Another long term variable X-ray source is aligned with a PANIC variable that peaked at K=12.6 in 2007 then disappeared in 2010. This variability is reminiscent of accreting compact binaries and shows the efficiency of an X-ray and K-band transient monitoring in order to constrain the nature of the population of X-ray sources in the Bulge.- Publication:
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American Astronomical Society Meeting Abstracts #218
- Pub Date:
- May 2011
- Bibcode:
- 2011AAS...21810803S