TY - JOUR
T1 - THE FIRST LOW-MASS BLACK HOLE X-RAY BINARY IDENTIFIED in QUIESCENCE OUTSIDE of A GLOBULAR CLUSTER
AU - Tetarenko, B. E.
AU - Bahramian, A.
AU - Arnason, R. M.
AU - Miller-Jones, J. C.A.
AU - Repetto, S.
AU - Heinke, C. O.
AU - MacCarone, T. J.
AU - Chomiuk, L.
AU - Sivakoff, G. R.
AU - Strader, J.
AU - Kirsten, F.
AU - Vlemmings, W.
N1 - Funding Information:
The authors thank Tom Russell for providing the radio data for SS Cyg and Chris Done for useful discussions. B.E.T., G.R.S., and C.O.H. acknowledge support by NSERC Discovery Grants. J.S. acknowledges support from NSF grant AST-1308124. J.C.A.M.J. is the recipient of an Australian Research Council Future Fellowship (FT140101082). W.V. acknowledges financial support from the Swedish Research Council. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. The search for an optical counterpart was based on observations made with the NASA/ESA Hubble Space Telescope, and obtained from the Hubble Legacy Archive, which is a collaboration between the Space Telescope Science Institute (STScI/NASA), the Space Telescope European Coordinating Facility (ST-ECF/ESA) and the Canadian Astronomy Data Center (CADC/NRC/CSA). The scientific results reported in this article are in part based on observations made by the Chandra X-ray Observatory. This research has made use of software provided by the Chandra X-ray Center (CXC) in the application package CIAO and the pysynphot package developed as part of STSDAS by the Space Telescope Science Institute (STScI). This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation. This work has also made use of NASA's Astrophysics Data System (ADS).
PY - 2016/7/1
Y1 - 2016/7/1
N2 - The observed relation between the X-ray and radio properties of low-luminosity accreting black holes (BHs) has enabled the identification of multiple candidate black hole X-ray binaries (BHXBs) in globular clusters (GCs). Here, we report an identification of the radio source VLA J213002.08+120904 (aka M15 S2), recently reported in Kirsten et al., as a BHXB candidate. They showed that the parallax of this flat-spectrum variable radio source indicates a - + 2.2 0.30.5 kpc distance, which identifies it as lying in the foreground of the GC M15. We determine the radio characteristics of this source and place a deep limit on the X-ray luminosity of ∼4 × 1029 erg s.1. Furthermore, we astrometrically identify a faint red stellar counterpart in archival Hubble images with colors consistent with a foreground star; at 2.2 kpc, its inferred mass is 0.1-0.2Me. We rule out that this object is a pulsar, neutron star X-ray binary, cataclysmic variable, or planetary nebula, concluding that VLA J213002.08+120904 is the first accreting BHXB candidate discovered in quiescence outside of a GC. Given the relatively small area over which parallax studies of radio sources have been performed, this discovery suggests a much larger population of quiescent BHXBs in our Galaxy, 2.6 ± 104-1.7 × 108 BHXBs at 3× confidence, than has been previously estimated (∼102-104) through population synthesis.
AB - The observed relation between the X-ray and radio properties of low-luminosity accreting black holes (BHs) has enabled the identification of multiple candidate black hole X-ray binaries (BHXBs) in globular clusters (GCs). Here, we report an identification of the radio source VLA J213002.08+120904 (aka M15 S2), recently reported in Kirsten et al., as a BHXB candidate. They showed that the parallax of this flat-spectrum variable radio source indicates a - + 2.2 0.30.5 kpc distance, which identifies it as lying in the foreground of the GC M15. We determine the radio characteristics of this source and place a deep limit on the X-ray luminosity of ∼4 × 1029 erg s.1. Furthermore, we astrometrically identify a faint red stellar counterpart in archival Hubble images with colors consistent with a foreground star; at 2.2 kpc, its inferred mass is 0.1-0.2Me. We rule out that this object is a pulsar, neutron star X-ray binary, cataclysmic variable, or planetary nebula, concluding that VLA J213002.08+120904 is the first accreting BHXB candidate discovered in quiescence outside of a GC. Given the relatively small area over which parallax studies of radio sources have been performed, this discovery suggests a much larger population of quiescent BHXBs in our Galaxy, 2.6 ± 104-1.7 × 108 BHXBs at 3× confidence, than has been previously estimated (∼102-104) through population synthesis.
KW - X-rays: binaries
KW - black hole physics
KW - radio continuum: general
KW - stars: individual (VLA J213002.08+120904)
UR - http://www.scopus.com/inward/record.url?scp=84978258565&partnerID=8YFLogxK
U2 - 10.3847/0004-637X/825/1/10
DO - 10.3847/0004-637X/825/1/10
M3 - Article
AN - SCOPUS:84978258565
SN - 0004-637X
VL - 825
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 1
M1 - 10
ER -