The ChaMPlane Bright X-Ray Sources—Galactic Longitudes l = 2°-358°
Abstract
The Chandra Multi-wavelength Plane (ChaMPlane) survey aims to constrain the Galactic population of mainly accretion-powered, but also coronal, low-luminosity X-ray sources (L X <~ 1033 erg s-1). To investigate the X-ray source content in the plane at fluxes F X >~ 3 × 10-14 erg s-1 cm-2, we study 21 of the brightest ChaMPlane sources, viz., those with >250 net counts (0.3-8 keV). By excluding the heavily obscured central part of the plane, our optical/near-infrared follow-up puts useful constraints on their nature. We have discovered two likely accreting white dwarf binaries. CXOPS J154305.5-522709 (CBS 7) is a cataclysmic variable showing periodic X-ray flux modulations on 1.2 hr and 2.4 hr given its hard spectrum the system is likely magnetic. We identify CXOPS J175900.8-334548 (CBS 17) with a late-type giant; if the X-rays are indeed accretion powered, it belongs to the small but growing class of symbiotic binaries lacking strong optical nebular emission lines. CXOPS J171340.5-395213 (CBS 14) is an X-ray transient that brightened gsim100 times. We tentatively classify it as a very late type (>M7) dwarf, of which few have been detected in X-rays. The remaining sources are (candidate) active galaxies, normal stars and active binaries, and a plausible young T Tauri star. The derived cumulative number density versus flux (log N-log S) relation for the Galactic sources appears flatter than expected for an isotropic distribution, indicating that we are seeing a non-local sample of mostly coronal sources. Our findings define source templates that we can use, in part, to classify the >104 fainter sources in ChaMPlane.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- March 2012
- DOI:
- 10.1088/0004-637X/748/1/31
- arXiv:
- arXiv:1201.5038
- Bibcode:
- 2012ApJ...748...31V
- Keywords:
-
- novae;
- cataclysmic variables;
- stars: flare;
- stars: individual: CXOPS J154305.5–522709 CXOPS J171340.5–395213 CXOPS J175900.8–334548 HD 9743;
- surveys;
- X-rays: binaries;
- X-rays: stars;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 15 pages, 9 figures, ApJ in press