Multiwavelength Study of a Hyperluminous X-Ray Source near NGC 6099: A Strong IMBH Candidate

• DOI: 10.3847/1538-4357/adbbee
• Publication Date: 2025-04-11T06:55:02Z
• Authors: Yi-Chi Chang; Roberto Soria; Albert K. H. Kong; Alister W. Graham; Kirill A. Grishin; Igor V. Chilingarian

Abstract We report on the intriguing properties of a variable X-ray source projected at outskirts elliptical galaxy NGC 6099 ( d ≈ 139 Mpc). If truly located near 6099, this is hyperluminous that reached an luminosity L X few times 10 42 erg s −1 in 2012 February (XMM-Newton data), about 50–100 brighter than 2009 May (Chandra) and 2023 August (XMM-Newton). The spectrum was soft all three epochs, with thermal component kT 0.2 keV power-law photon index >3. Such make it strong candidate for intermediate-mass black hole (IMBH). also discovered point-like, blue optical counterpart m g ,Vega 24.7 mag, M −11.2 mag), from images taken by Canada–France–Hawaii Telescope later confirmed Hubble Space observations. continuum can be modeled as stellar emission compact star cluster or X-ray-irradiated accretion disk, consistent IMBH scenario. discuss alternative explanations nature system. A possible scenario tidal stripping orbiting star, repeated outbursts every years. An possibility seen shocked gas self-intersecting stream during rising phase disruption event, while emissions were fully formed disk.