A dynamic black hole corona in an active galaxy through X-ray reverberation mapping. (arXiv:2001.06454v2 [astro-ph.HE] UPDATED)

A dynamic black hole corona in an active galaxy through X-ray reverberation mapping. (arXiv:2001.06454v2 [astro-ph.HE] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Alston_W/0/1/0/all/0/1">William N. Alston</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fabian_A/0/1/0/all/0/1">Andrew C. Fabian</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kara_E/0/1/0/all/0/1">Erin Kara</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Parker_M/0/1/0/all/0/1">Michael L. Parker</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dovciak_M/0/1/0/all/0/1">Michal Dovciak</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pinto_C/0/1/0/all/0/1">Ciro Pinto</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Jiang_J/0/1/0/all/0/1">Jiachen Jiang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Middleton_M/0/1/0/all/0/1">Matthew J. Middleton</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Miniutti_G/0/1/0/all/0/1">Giovanni Miniutti</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Walton_D/0/1/0/all/0/1">Dominic J. Walton</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wilkins_D/0/1/0/all/0/1">Dan R. Wilkins</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Buisson_D/0/1/0/all/0/1">Douglas J. K. Buisson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Caballero_Garcia_M/0/1/0/all/0/1">Maria D. Caballero-Garcia</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cackett_E/0/1/0/all/0/1">Edward M. Cackett</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Marco_B/0/1/0/all/0/1">Barbara De Marco</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gallo_L/0/1/0/all/0/1">Luigi C. Gallo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lohfink_A/0/1/0/all/0/1">Anne M. Lohfink</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Reynolds_C/0/1/0/all/0/1">Chris S. Reynolds</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Uttley_P/0/1/0/all/0/1">Phil Uttley</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Young_A/0/1/0/all/0/1">Andrew J. Young</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zogbhi_A/0/1/0/all/0/1">Abderahmen Zogbhi</a>

X-ray reverberation echoes are assumed to be produced in the strongly
distorted spacetime around accreting supermassive black holes. This signal
allows us to spatially map the geometry of the inner accretion flow – a region
which cannot yet be spatially resolved by any telescope – and provides a direct
measure of the black hole mass and spin. The reverberation timescale is set by
the light travel path between the direct emission from a hot X-ray corona and
the reprocessed emission from the inner edge of the accretion disc. However,
there is an inherent degeneracy in the reverberation signal between black hole
mass, inner disc radius and height of the illuminating corona above the disc.
Here, we use a long X-ray observation of the highly-variable active galaxy,
IRAS 13224-3809, to track the reverberation signal as the system evolves on
timescales of a day. With the inclusion of all the relativistic effects,
modelling reveals that the height of the X-ray corona increases with increasing
luminosity, providing a dynamic view of the inner accretion region. This
simultaneous modelling allows us to break the inherent degeneracies and obtain
an independent timing-based estimate for the mass and spin of the black hole.
The uncertainty on black hole mass is comparable to the leading optical
reverberation method, making X-ray reverberation a powerful technique,
particularly for sources with low optical variability.

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