First hard X-ray detection and broad band X-ray study of the unidentified transient AX J1949.8+2534

Abstract

We present the results from INTEGRAL and Swift/XRT observations of the hitherto poorly studied unidentified X-ray transient AX J1949.8+2534, and on archival multiwavelength observations of field objects. Bright hard X-ray outbursts have been discovered above 20 keV for the first time, the measured duty cycle and dynamic range are of the order of 4% and >630, respectively. The source was also detected during a low soft X-ray state (2x10E-12 erg cmE-2 sE-1) thanks to a Swift/XRT followup, which allowed for the first time to perform a soft X-ray spectral analysis as well as significantly improve the source positional uncertainty from arcminute to arcsecond size. From archival near-infrared data, we pinpointed two bright objects as most likely counterparts whose photometric properties are compatible with an early type spectral nature. This strongly supports a High Mass X-ray Binary (HMXB) scenario for AX J1949.8+2534, specifically a Supergiant Fast X-ray Transient (more likely) or alternatively a Be HMXB.

Accepted for publication in MNRAS. 8 pages, 6 figures, 4 tables

References in corpus (13)

• The UKIRT Infrared Deep Sky Survey (UKIDSS)
• The UKIDSS Galactic Plane Survey
• Unveiling supergiant fast X-ray transient sources with INTEGRAL
• 20-100 keV properties of cataclysmic variables detected in the INTEGRAL/IBIS survey
• Monitoring Supergiant Fast X-ray Transients with Swift. I. Behavior outside outbursts
• The behavior of subluminous X-ray transients near the Galactic center as observed using the X-ray telescope aboard Swift
• Intermediate polars in the Swift/BAT survey: Spectra and white dwarf masses
• A search for counterparts to massive X-ray binaries using photometric catalogues
• Properties of the Galactic population of cataclysmic variables in hard X-rays
• INTEGRAL/IBIS and Swift/XRT observations of hard cataclysmic variables
• Accretion regimes in the X-ray pulsar 4U 1901+03
• Chasing the Identification of ASCA Galactic Objects (ChIcAGO) - An X-ray Survey of Unidentified Sources in the Galactic Plane I: Source Sample and Initial Results
• INTEGRAL discovery of unusually long broad-band X-ray activity from the Supergiant Fast X-ray Transient IGR J18483-0311

Cited by in corpus (2)

• Chasing candidate Supergiant Fast X-ray Transients in the 1,000 orbits INTEGRAL/IBIS catalog
• Chandra, MDM, Swift, and NuSTAR observations confirming the SFXT nature of AX J1949.8+2534