Spectra and Variability of X-ray emission from accreting black holes
Lead Research Organisation:
University of Cambridge
Department Name: Institute of Astronomy
Abstract
Studying X-Ray spectra and timing of emission from accreting black holes.
As matter falls onto black holes, it heats up and emits high energy radiation. Studying the precise nature of this radiation allows inferences to be made about the nature of the structure around the black hole.
It has been learnt that an accretion disc forms which typically emits in UV for the supermassive black holes at the centre of galaxies and in soft X-rays for stellar mass black holes.
Some of this emission is then scattered to X-ray wavelengths by a population of hot electrons, known as a corona, whose exact nature is unknown.
New high-energy observatories, in particular NuSTAR, are able to take spectra of the emission from this corona up to its high-energy cut-off, providing information about important properties such as the temperature of the electrons.
The accretion disc also provides a surface off of which photons can scatter, forming atomic reflection features. How atomic lines are shifted by general relativistic effects near the central black hole can provide information about the inner accretion disc and the spacetime in which it resides.
As the emission leaves the black hole to reach us, it passes through clouds of hot gas, which imprint absorption features which may be used to determine the structure of the gas clouds around the black hole.
The emission is also strongly variable and studying how different bands vary with respect to each other can provide information on their relationship and geometry.
When coronal emission is reflected from the disc, changes in the reflected components are expected to show a lag relative to the direct coronal emission. The size of this lag sets an upper bound on the distance to the reflecting region of the disc, given by the distance light can travel in this time.
Combining these various sources of information will allow further details of accretion around black holes to be elucidated.
As matter falls onto black holes, it heats up and emits high energy radiation. Studying the precise nature of this radiation allows inferences to be made about the nature of the structure around the black hole.
It has been learnt that an accretion disc forms which typically emits in UV for the supermassive black holes at the centre of galaxies and in soft X-rays for stellar mass black holes.
Some of this emission is then scattered to X-ray wavelengths by a population of hot electrons, known as a corona, whose exact nature is unknown.
New high-energy observatories, in particular NuSTAR, are able to take spectra of the emission from this corona up to its high-energy cut-off, providing information about important properties such as the temperature of the electrons.
The accretion disc also provides a surface off of which photons can scatter, forming atomic reflection features. How atomic lines are shifted by general relativistic effects near the central black hole can provide information about the inner accretion disc and the spacetime in which it resides.
As the emission leaves the black hole to reach us, it passes through clouds of hot gas, which imprint absorption features which may be used to determine the structure of the gas clouds around the black hole.
The emission is also strongly variable and studying how different bands vary with respect to each other can provide information on their relationship and geometry.
When coronal emission is reflected from the disc, changes in the reflected components are expected to show a lag relative to the direct coronal emission. The size of this lag sets an upper bound on the distance to the reflecting region of the disc, given by the distance light can travel in this time.
Combining these various sources of information will allow further details of accretion around black holes to be elucidated.
Organisations
People |
ORCID iD |
Andrew Fabian (Primary Supervisor) | |
Douglas Buisson (Student) |
Publications
Buisson D
(2017)
Ultraviolet and X-ray variability of active galactic nuclei with Swift
in Monthly Notices of the Royal Astronomical Society
Buisson D
(2018)
NuSTAR observations of Mrk 766: distinguishing reflection from absorption
in Monthly Notices of the Royal Astronomical Society
Buisson D
(2018)
Is there a UV/X-ray connection in IRAS 13224-3809?
Buisson D
(2018)
Is there a UV/X-ray connection in IRAS 13224-3809?
in Monthly Notices of the Royal Astronomical Society
Buisson D.
(2017)
Long term multiwavelength studies of the corona/disc connection in AGN
in The X-ray Universe 2017
Buisson D. J. K.
(2017)
Is there a UV/X-ray connection in IRAS 13224-3809?
in ArXiv e-prints
Fabian A.
(2017)
An overview of results emerging from a 1.5 Ms long exposure of the highly variable AGN IRAS13224-3809
in The X-ray Universe 2017
Jiang(???) J
(2018)
The 1.5 Ms observing campaign on IRAS 13224-3809 - I. X-ray spectral analysis
in Monthly Notices of the Royal Astronomical Society
Lohfink Anne
(2017)
The broad-band X-ray spectra of Mrk 926, 4U 1344-60 and ESO 141-G055
in AAS/High Energy Astrophysics Division #16
Lohfink Anne
(2016)
New insights into AGN coronae
in AAS/High Energy Astrophysics Division #15
Parker M
(2018)
Constraining the geometry of AGN outflows with reflection spectroscopy
in Monthly Notices of the Royal Astronomical Society: Letters
Parker M
(2017)
Revealing the ultrafast outflow in IRAS 13224-3809 through spectral variability
in Monthly Notices of the Royal Astronomical Society
Parker M
(2017)
The response of relativistic outflowing gas to the inner accretion disk of a black hole
in Nature
Parker M
(2018)
Using principal component analysis to understand the variability of PDS 456
in Monthly Notices of the Royal Astronomical Society
Parker M.
(2017)
Rapidly variable relatvistic absorption
in The X-ray Universe 2017
Pinto C
(2018)
Ultrafast outflows disappear in high-radiation fields
in Monthly Notices of the Royal Astronomical Society
Pinto C
(2018)
Ultrafast outflows disappear in high-radiation fields
Pinto Ciro
(2017)
Ultrafast outflows disappear in high radiation fields
in ArXiv e-prints
Studentship Projects
Project Reference | Relationship | Related To | Start | End | Student Name |
---|---|---|---|---|---|
ST/N503988/1 | 01/10/2015 | 31/03/2021 | |||
1637922 | Studentship | ST/N503988/1 | 01/10/2015 | 31/03/2019 | Douglas Buisson |