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The absence of a thin disc in M81*
- Source :
- Young, A, McHardy, I, Emmanoulopoulos, D & Connolly, S 2018, ' The absence of a thin disc in M81* ', Monthly Notices of the Royal Astronomical Society, vol. 476, no. 4, pp. 5698–5703 . https://doi.org/10.1093/mnras/sty509
- Publication Year :
- 2018
- Publisher :
- Oxford University Press (OUP), 2018.
-
Abstract
- We present the results of simultaneous Suzaku and NuSTAR observations of the nearest Low-Luminosity Active Galactic Nucleus (LLAGN), M81*. The spectrum is well described by a cut-off power law plus narrow emission lines from Fe K$\alpha$, Fe XXV and Fe XXVI. There is no evidence of Compton reflection from an optically thick disc, and we obtain the strongest constraint on the reflection fraction in M81* to date, with a best-fit value of $R = 0.0$ with an upper limit of $R < 0.1$. The Fe K$\alpha$ line may be produced in optically thin, $N_H = 1 \times 10^{23}$ cm$^{-2}$, gas located in the equatorial plane that could be the broad line region. The ionized iron lines may originate in the hot, inner accretion flow. The X-ray continuum shows significant variability on $\sim 40$ ks timescales suggesting that the primary X-ray source is $\sim 100$s of gravitational radii in size. If this X-ray source illuminates any putative optically thick disc, the weakness of reflection implies that such a disc lies outside a few $\times 10^3$ gravitational radii. An optically thin accretion flow inside a truncated optically thick disc appears to be a common feature of LLAGN that are accreting at only a tiny fraction of the Eddington limit.<br />Comment: 7 pages, 7 figures, to appear in MNARS
- Subjects :
- High Energy Astrophysical Phenomena (astro-ph.HE)
Physics
Active galactic nucleus
010308 nuclear & particles physics
Astrophysics::High Energy Astrophysical Phenomena
FOS: Physical sciences
Astronomy and Astrophysics
Astrophysics::Cosmology and Extragalactic Astrophysics
Astrophysics
Thin disc
01 natural sciences
Power law
Accretion (astrophysics)
Gravitation
symbols.namesake
Space and Planetary Science
Ionization
0103 physical sciences
Eddington luminosity
symbols
Astrophysics::Earth and Planetary Astrophysics
Emission spectrum
Astrophysics - High Energy Astrophysical Phenomena
010303 astronomy & astrophysics
Astrophysics::Galaxy Astrophysics
Subjects
Details
- ISSN :
- 13652966 and 00358711
- Volume :
- 476
- Database :
- OpenAIRE
- Journal :
- Monthly Notices of the Royal Astronomical Society
- Accession number :
- edsair.doi.dedup.....d8daebadb720b44bed46f91e48f7a9e4