An upper observable black hole mass scale for tidal disruption events with thermal X-ray spectra. (arXiv:2104.06177v2 [astro-ph.HE] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Mummery_A/0/1/0/all/0/1">Andrew Mummery</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Balbus_S/0/1/0/all/0/1">Steven Balbus</a>

We comprehensively model the X-ray luminosity emergent from time dependent
relativistic accretion discs, developing analytical models of the X-ray
luminosity of thermal disc systems as a function of black hole mass $M$, disc
mass $M_d$, and disc $alpha$-parameter. The X-ray properties of these
solutions will be directly relevant for understanding TDE observations. We
demonstrate an extremely strong suppression of thermal X-ray luminosity from
large mass black holes, $L_X sim exp(-m^{7/6})$, where $m$ is a dimensionless
mass, roughly the the black hole mass in unity of $10^6$M$_odot$. This strong
suppression results in upper-observable black hole mass limits, which we
demonstrate to be of order $M_{rm lim} simeq 3 times 10^7 M_odot$, above
which thermal X-ray emission will not be observable. This upper observable
black hole mass limit is a function of the remaining disc parameters, and the
full dependence can be described analytically (eq. 82). We demonstrate that the
current population of observed X-ray TDEs is indeed consistent with an upper
black hole mass limit of order $M sim 10^7M_odot$, consistent with our
analysis.

We comprehensively model the X-ray luminosity emergent from time dependent
relativistic accretion discs, developing analytical models of the X-ray
luminosity of thermal disc systems as a function of black hole mass $M$, disc
mass $M_d$, and disc $alpha$-parameter. The X-ray properties of these
solutions will be directly relevant for understanding TDE observations. We
demonstrate an extremely strong suppression of thermal X-ray luminosity from
large mass black holes, $L_X sim exp(-m^{7/6})$, where $m$ is a dimensionless
mass, roughly the the black hole mass in unity of $10^6$M$_odot$. This strong
suppression results in upper-observable black hole mass limits, which we
demonstrate to be of order $M_{rm lim} simeq 3 times 10^7 M_odot$, above
which thermal X-ray emission will not be observable. This upper observable
black hole mass limit is a function of the remaining disc parameters, and the
full dependence can be described analytically (eq. 82). We demonstrate that the
current population of observed X-ray TDEs is indeed consistent with an upper
black hole mass limit of order $M sim 10^7M_odot$, consistent with our
analysis.

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