An Ultraluminous Supersoft X-ray Source in M81: An Intermediate-Mass Black Hole - AstrophysicsReport as inadecuate




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Abstract: Ultraluminous supersoft X-ray sources ULSSS exhibit supersoft spectra withblackbody temperatures of 50-100 eV and bolometric luminosities above $10^{39}$erg s$^{-1}$, and are possibly intermediate mass black holes IMBHs of$\ge10^3 M \odot$ or massive white dwarfs that are progenitors of type Iasupernovae. In this letter we report our optical studies of such a source inM81, M81-ULS1, with HST archive observations. M81-ULS1 is identified with apoint-like object, the spectral energy distribution of which reveals a bluecomponent in addition to the companion of an AGB star. The blue component isconsistent with the power-law as expected from the geometrically-thin accretiondisk around an IMBH accretor, but inconsistent with the power-law as expectedfrom the X-ray irradiated flared accretion disk around a white dwarf accretor.This result is strong evidence that M81-ULS1 is an IMBH instead of a whitedwarf.



Author: Jifeng Liu CfA, Rosanne Di Stefano CfA

Source: https://arxiv.org/







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