* Astronomy

Title: The 2013 outburst of a transient very faint X-ray binary, 23" from Sgr A*
Author: E. W. Koch (1,2), A. Bahramian (1), C. O. Heinke (1), K. Mori (3), N. Rea (4,5), N. Degenaar (6), D. Haggard (7), R. Wijnands (4), G. Ponti (8), J. M. Miller (6), F. Yusef-Zadeh (8), F. Dufour (9), W. D. Cotton (10), F. K. Baganoff (11), M. T. Reynolds (6) ((1) University of Alberta, (2) UBC-Okanagan, (3) Columbia University, (4) Astronomical Institute Anton Pannekoek, (5) Institute of Space Sciences (CSIC-IEEC), (6) University of Michigan, (7) Northwestern University, (8) University of Southampton, (9) McGill University, (10) National Radio Astronomy Observatory, (11) Kavli Institute for Astrophysics and Space Research)

We report observations using the Swift/XRT, NuSTAR, and Chandra X-ray telescopes of the transient X-ray source CXOGC J174540.0-290005, during its 2013 outburst. Due to its location in the field of multiple observing campaigns targeting Sgr A*, this is one of the best-studied outbursts of a very faint X-ray binary (VFXB; peak LX<10^36erg/s) yet recorded, with detections in 173 ks of X-ray observations over 50 days. VFXBs are of particular interest, due to their unusually low outburst luminosities and time-averaged mass transfer rates, which are hard to explain within standard accretion physics and binary evolution. The 2013 outburst of CXOGC J174540.0-290005 peaked at LX(2-10 keV)=5.0 x10^35 erg/s, and all data above 10^34 ergs/s were well-fit by an absorbed power-law of photon index ~1.7, extending from 2 keV out to ~70 keV. We discuss the implications of these observations for the accretion state of CXOGC J174540.0-290005.

Read more (2482kb, PDF)