J/ApJ/920/120ivo://CDS.VizieR/J/ApJ/920/120doi:10.26093/cds/vizier.19200120CDSYao Y.Kulkarni S.R.Burdge K.B.Caiazzo I.De K.Dong D.,Fremling C.Kasliwal M.M.Kupfer T.van Roestel J.Sollerman J.,Bagdasaryan A.Bellm E.C.Cenko S.B.Drake A.J.Duev D.A.,Graham M.J.Kaye S.Masci F.J.Miranda N.Prince T.A.Riddle R.,Rusholme B.Soumagnac M.T.2024-11-06T20:23:23Z2024-03-13T08:50:29ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frmultiple-starsblack-holesinfrared-photometryvisible-astronomyphotometryAT2019wey (SRGA J043520.9+552226, SRGE J043523.3+552234) is a transient first reported by the ATLAS optical survey in 2019 December. It rose to prominence upon detection, three months later, by the Spektrum-Roentgen-Gamma (SRG) mission in its first all-sky survey. X-ray observations reported in Yao et al. suggest that AT2019wey is a Galactic low-mass X-ray binary (LMXB) with a black hole (BH) or neutron star (NS) accretor. Here we present ultraviolet, optical, near-infrared, and radio observations of this object. We show that the companion is a short-period (P<~16hr) low-mass (<1M{sun}) star. We consider AT2019wey to be a candidate BH system since its locations on the Lradio-LX and Lopt-LX diagrams are closer to BH binaries than NS binaries. We demonstrate that from 2020 June to August, despite the more than 10 times brightening at radio and X-ray wavelengths, the optical luminosity of AT2019wey only increased by 1.3-1.4 times. We interpret the UV/optical emission before the brightening as thermal emission from a truncated disk in a hot accretion flow and the UV/optical emission after the brightening as reprocessing of the X-ray emission in the outer accretion disk. AT2019wey demonstrates that combining current wide-field optical surveys and SRG provides a way to discover the emerging population of short-period BH LMXB systems with faint X-ray outbursts.2021ApJ...920..120Yhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/920/120CatalogResearchIsServedByTAP VizieR generic servicerelated-toIX/10 : ROSAT All-Sky Bright Source Catalogue (1RXS) (Voges+ 1999)VIII/65 : 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998)J/A+A/588/A103 : Second ROSAT all-sky survey source catalog (Boller+, 2016)J/A+A/593/A68 : PTF12os & iPTF13bvn spectra and light curves (Fremling+, 2016)J/ApJS/222/15 : WATCHDOG all-sky database of Galactic BHXBs (Tetarenko+, 2016)J/ApJ/900/46 : UV, opt and IR light curve of supernova SN2019dge (Yao+, 2020)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/920/120https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/920/120http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/920/120https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/920/120https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/920/120http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/920/120GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticalInfrareddefaultJ/ApJ/920/120/table5ZTF forced photometry of AT2019weyrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMJD[58206/59184] Modified Julian Datedtime.epochdoubleFlux[-42.9/466] Flux density in FilteruJyphot.flux.density;em.optfloate_Flux[1/39] Uncertainty in FluxuJystat.error;phot.fluxfloatFiltFilter used; g or rinstr.setup;instr.filterchar