X-ray images of hot accretion flows

Feryal Ozel, Tiziana Di Matteo

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

We consider the X-ray emission due to bremsstrahlung processes from spherically symmetric, low radiative efficiency hot accretion flows around supermassive and galactic black holes. We calculate surface brightness profiles and Michelson visibility functions for a range of density profiles, p ̃ r -3/2 + p, with 0 < p < 1, to allow for the presence of outflows. We find that although the 1 ke V emitting region in these flows can always extend up to 106 Schwarzschild radii (Rs), their surface brightness profiles and visibility functions are strongly affected by the specific density profile. The advection-dominated solutions with no outflows (p = 0) lead to centrally peaked profiles with characteristic sizes of only a few tens of Rs. Solutions with strong outflows (p ̃ 1) lead to flat intensity profiles with significantly larger characteristic sizes of up to 106Rs. This implies that low-luminosity galactic nuclei, such as M87, may appear as extended X-ray sources when observed with current X-ray imaging instruments. We show that X-ray brightness profiles and their associated visibility functions may be powerful probes for determining the relevant mode of accretion and, in turn, the properties of hot accretion flows. We discuss the implications of our results for observations with the Chandra X-Ray Observatory and the proposed X-ray interferometer MAXIM.

Original languageEnglish (US)
Pages (from-to)213-218
Number of pages6
JournalAstrophysical Journal
Volume548
Issue number1 PART 1
DOIs
StatePublished - Feb 10 2001
Externally publishedYes

Fingerprint

accretion
profiles
visibility
x rays
outflow
brightness
galactic nuclei
interferometer
advection
bremsstrahlung
observatory
probe
observatories
interferometers
luminosity
radii
probes

Keywords

  • Accretion, accretion disks
  • Black hole physics
  • Galaxies: nuclei
  • Radiation mechanisms: thermal
  • X-rays: galaxies

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

X-ray images of hot accretion flows. / Ozel, Feryal; Di Matteo, Tiziana.

In: Astrophysical Journal, Vol. 548, No. 1 PART 1, 10.02.2001, p. 213-218.

Research output: Contribution to journalArticle

Ozel, F & Di Matteo, T 2001, 'X-ray images of hot accretion flows', Astrophysical Journal, vol. 548, no. 1 PART 1, pp. 213-218. https://doi.org/10.1086/318658
Ozel, Feryal ; Di Matteo, Tiziana. / X-ray images of hot accretion flows. In: Astrophysical Journal. 2001 ; Vol. 548, No. 1 PART 1. pp. 213-218.
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