SRGA J181414.6-225604: A New Galactic Symbiotic X-Ray Binary Outburst Triggered by an Intense Mass-loss Episode of a Heavily Obscured Mira Variable

August 2022 • 2022ApJ...935...36D

Authors • De, Kishalay • Mereminskiy, Ilya • Soria, Roberto • Conroy, Charlie • Kara, Erin • Anand, Shreya • Ashley, Michael C. B. • Boyer, Martha L. • Chakrabarty, Deepto • Grefenstette, Brian • Hankins, Matthew J. • Hillenbrand, Lynne A. • Jencson, Jacob E. • Karambelkar, Viraj • Kasliwal, Mansi M. • Lau, Ryan M. • Lutovinov, Alexander • Moore, Anna M. • Ng, Mason • Panagiotou, Christos • Pasham, Dheeraj R. • Semena, Andrey • Simcoe, Robert • Soon, Jamie • Srinivasaragavan, Gokul P. • Travouillon, Tony • Yao, Yuhan

Abstract • We present the discovery and multiwavelength characterization of SRGA J181414.6-225604, a Galactic hard X-ray transient discovered during the ongoing SRG/ART-XC sky survey. Using data from the Palomar Gattini-IR survey, we identify a spatially and temporally coincident variable infrared (IR) source, IRAS 18111-2257, and classify it as a very-late-type (M7-M8), long-period (1502 ± 24 days), and luminous (M _K ≈ -9.9 ± 0.2) O-rich Mira donor star located at a distance of ≈14.6^+2.9 _-2.3 kpc. Combining multicolor photometric data over the last ≈25 yr, we show that the IR counterpart underwent a recent (starting ≈800 days before the X-ray flare) enhanced mass-loss (reaching ≈2.1 × 10^-5 M _⊙ yr^-1) episode, resulting in an expanding dust shell obscuring the underlying star. Multi-epoch follow-up observations from Swift, NICER, and NuSTAR reveal a ≈200 day long X-ray outburst reaching a peak luminosity of L _X ≈ 2.5 × 10³⁶ erg s^-1, characterized by a heavily absorbed (N _H ≈ 6 × 10²² cm^-2) X-ray spectrum consistent with an optically thick Comptonized plasma. The X-ray spectral and timing behavior suggest the presence of clumpy wind accretion, together with a dense ionized nebula overabundant in silicate material surrounding the compact object. Together, we show that SRGA J181414.6-225604 is a new symbiotic X-ray binary in outburst, triggered by an intense dust-formation episode of a highly evolved donor. Our results offer the first direct confirmation for the speculated connection between enhanced late-stage donor mass loss and the active lifetimes of symbiotic X-ray binaries.

Links

• PREPRINT http://arxiv.org/abs/2205.09139
• ELECTR https://doi.org/10.3847%2F1538-4357%2Fac7c6e
• SIMBAD http://simbad.u-strasbg.fr/simbo.pl?bibcode=2022ApJ...935...36D
• PDF https://iopscience.iop.org/article/10.3847/1538-4357/ac7c6e/pdf
• DATA http://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/935/36
• DATA http://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/biblink.pl?code=2022ApJ...935...36D
• DATA https://archive.stsci.edu/mastbibref.php?bibcode=2022ApJ...935...36D
• DATA https://irsa.ipac.caltech.edu/bibdata/2022/D/2022ApJ...935...36D.html