2004/07/09 by Ken Ebisawa, K. Ebisawa, A. Paizis +40
Engineering · Physics and Astronomy · #Astronomical Observations and Instrumentation #Astrophysical Phenomena and Observations #Astrophysics (astro-ph) #FOS: Physical sciences #Gamma-ray bursts and supernovae #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0407205
Proceedings for 5th INTEGRAL workshop in February 2004, Munchen, Germany
arxiv created 2004/07/09 · openalex publication_date 2004/07/09 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Using the Chandra ACIS-I instruments, we have carried out a deep X-ray\nobservation on the Galactic plane region at (l,b) ~ (28.5, 0.0), where no\ndiscrete X-ray sources have been known previously. We have detected, as well as\nstrong diffuse emission, 274 new point X-ray sources (4 sigma confidence)\nwithin two partially overlapping fields (~250 arcmin2 in total) down to the\nflux limit ~3 x 10-15 erg s-1 cm-2 (2 -- 10 keV) and ~ 7 x 10-16\nerg s-1 cm-2 (0.5 -- 2 keV). We clearly resolved point sources and the\nGalactic diffuse emission, and found that ~ 90 % of the flux observed in our\nfield of view originates from diffuse emission. Many point sources are detected\neither in the soft X-ray band (below 2 keV) or in the hard band (above 2 keV),\nand only a small number of sources are detected in both energy bands.\n On the other hand, most soft X-ray sources are considered to be nearby X-ray\nactive stars. We have carried out a follow-up near-infrared (NIR) observation\nusing SOFI at ESO/NTT. Most of the soft X-ray sources were identified, whereas\nonly a small number of hard X-ray sources had counterparts in NIR. Using both\nX-ray and NIR information, we can efficiently classify the point X-ray sources\ndetected in the Galactic plane. We conclude that most of the hard X-ray sources\nare background Active Galactic Nuclei seen through the Milky Way, whereas\nmajority of the soft X-ray sources are nearby X-ray active stars.\n