@article{fd363559bf9f4cd9a92feeeae0201058,
title = "Multiwavelength observations reveal a faint candidate black hole X-ray binary in IGR J17285-2922",
abstract = "IGR J17285-2922 is a known X-ray binary with a low peak 2-10 keV X-ray luminosity of ∼1036 erg s-1 during outburst. IGR J17285-2922 exhibited two outbursts in 2003 and 2010 and went into outburst again in 2019. We have monitored this ∼4-month long 2019 outburst with Swift in X-ray and the Very Large Array in radio. We have also obtained four optical spectra with the Gran Telescopio Canarias and Southern Astrophysical Research Telescope, three optical photometry measurements with the Las Cumbres Observatory, and one near-infrared spectrum with the Gemini South telescope. The ratio between its X-ray and radio luminosity is consistent with both samples of neutron star and black hole (BH) X-ray binaries, while the ratio between the X-ray and optical luminosity is consistent with BH X-ray binaries. Studying the evolution of its X-ray power-law index throughout the outburst, we find additional evidence for a BH as compact object. The four optical spectra show no H α emission and the nIR spectrum shows no Brγ emission, suggesting that the donor star could be hydrogen-poor and hence that IGR J17285-2922 might have an ultracompact binary orbit. The shape of the X-ray light curve is well described by an exponential, followed by a linear decay, from which we obtain a relation between the orbital period Porb and the binary mass ratio. We discuss how this relation is consistent with theoretical predictions and known ultracompact X-ray binaries. Lastly, we discuss how the observed properties are reminiscent of short-Porb BH X-ray binaries.",
keywords = "X-rays: binaries, accretion, accretion discs, stars: individual: IGR J17285-2922",
author = "M. Stoop and {Van Den Eijnden}, J. and N. Degenaar and A. Bahramian and Swihart, {S. J.} and J. Strader and F. Jim{\'e}nez-Ibarra and T. Mu{\~n}oz-Darias and {Armas Padilla}, M. and Shaw, {A. W.} and Maccarone, {T. J.} and R. Wijnands and Russell, {T. D.} and Santisteban, {J. V.Hern{\'a}ndez} and Miller-Jones, {J. C.A.} and Russell, {D. M.} and D. Maitra and Heinke, {C. O.} and Sivakoff, {G. R.} and F. Lewis and Bramich, {D. M.}",
note = "Funding Information: We thank the referee for their comments that improved the quality of this work. We thank Tom Marsh for the use of MOLLY. JvdE and ND are supported by a Vidi grant from the Netherlands Organization for Scientific Research (NWO) awarded to ND. MAP and TMD acknowledge support from the State Research Agency of the Spanish MCIU and the European Regional Development Fund (ERDF) under grant AYA2017-83216-P. TMD acknowledges support from the Consejer{\'i}a de Econom{\'i}a, Conocimiento y Empleo del Gobierno de Canarias and the ERDF under grant with reference ProID2020 010104. TMD acknowledges support via the Ram{\'o}n y Cajal Fellowship RYC-2015-18148. TDR acknowledges financial contribution from the agreement ASI-INAF n.2017-14-H.0. The Faulkes Telescope Project is an education partner of Las Cumbres Observatory (LCO). The Faulkes Telescopes are maintained and operated by LCO. This research hasmade use of data and software provided by the High Energy Astrophysics Science Archive Research Center (HEASARC) and NASA's Astrophysics Data System Bibliographic Services. This work made use of data supplied by the UK Swift Science Data Centre at the University of Leicester. Publisher Copyright: {\textcopyright} 2021 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society.",
year = "2021",
month = oct,
day = "1",
doi = "10.1093/mnras/stab2127",
language = "English",
volume = "507",
pages = "330--349",
journal = "Monthly Notices of the Royal Astronomical Society",
issn = "0035-8711",
number = "1",
}