Tidal disruptions of main sequence stars — IV. Relativistic effects and dependence on black hole mass. (arXiv:2001.03504v3 [astro-ph.HE] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Ryu_T/0/1/0/all/0/1">Taeho Ryu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Krolik_J/0/1/0/all/0/1">Julian Krolik</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Piran_T/0/1/0/all/0/1">Tsvi Piran</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Noble_S/0/1/0/all/0/1">Scott C. Noble</a>
Using a suite of fully relativistic hydrodynamic simulations applied to
main-sequence stars with realistic internal density profiles, we examine full
and partial tidal disruptions across a wide range of black hole mass
($10^{5}leq M_{rm BH}/mathrm{M}_{odot}leq 5times 10^{7}$) and stellar
mass ($0.3 leq M_{star} /mathrm{M}_{odot}leq 3$) as larger $M_{rm BH}$
leads to stronger relativistic effects. For fixed $M_{star}$, as $M_{rm BH}$
increases, the ratio of the maximum pericenter distance yielding full
disruptions ($mathcal{R}_{rm t}$) to its Newtonian prediction rises rapidly,
becoming triple the Newtonian value for $M_{rm BH} = 5times10^{7}~{rm
M}_odot$, while the ratio of the energy width of the stellar debris for full
disruptions to the Newtonian prediction decreases steeply, resulting in a
factor of two correction at $M_{rm BH} = 5 times 10^7~{rm M}_odot$. We find
that for partial disruptions, the fractional remnant mass for a given ratio of
the pericenter to $mathcal{R}_{rm t}$ is higher for larger $M_{rm BH}$.
These results have several implications. As $M_{rm BH}$ increases above $sim
10^7~{rm M}_odot$, the cross section for complete disruptions is suppressed
by competition with direct capture. However, the cross section ratio for
partial to complete disruptions depends only weakly on $M_{rm BH}$. The
relativistic correction to the debris energy width delays the time of peak
mass-return rate and diminishes the magnitude of the peak return rate. For
$M_{rm BH} gtrsim 10^7~{rm M}_odot$, the $M_{rm BH}$-dependence of the
full disruption cross section and the peak mass-return rate and time is
influenced more by relativistic effects than by Newtonian dynamics.
Using a suite of fully relativistic hydrodynamic simulations applied to
main-sequence stars with realistic internal density profiles, we examine full
and partial tidal disruptions across a wide range of black hole mass
($10^{5}leq M_{rm BH}/mathrm{M}_{odot}leq 5times 10^{7}$) and stellar
mass ($0.3 leq M_{star} /mathrm{M}_{odot}leq 3$) as larger $M_{rm BH}$
leads to stronger relativistic effects. For fixed $M_{star}$, as $M_{rm BH}$
increases, the ratio of the maximum pericenter distance yielding full
disruptions ($mathcal{R}_{rm t}$) to its Newtonian prediction rises rapidly,
becoming triple the Newtonian value for $M_{rm BH} = 5times10^{7}~{rm
M}_odot$, while the ratio of the energy width of the stellar debris for full
disruptions to the Newtonian prediction decreases steeply, resulting in a
factor of two correction at $M_{rm BH} = 5 times 10^7~{rm M}_odot$. We find
that for partial disruptions, the fractional remnant mass for a given ratio of
the pericenter to $mathcal{R}_{rm t}$ is higher for larger $M_{rm BH}$.
These results have several implications. As $M_{rm BH}$ increases above $sim
10^7~{rm M}_odot$, the cross section for complete disruptions is suppressed
by competition with direct capture. However, the cross section ratio for
partial to complete disruptions depends only weakly on $M_{rm BH}$. The
relativistic correction to the debris energy width delays the time of peak
mass-return rate and diminishes the magnitude of the peak return rate. For
$M_{rm BH} gtrsim 10^7~{rm M}_odot$, the $M_{rm BH}$-dependence of the
full disruption cross section and the peak mass-return rate and time is
influenced more by relativistic effects than by Newtonian dynamics.
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