X-ray spectral and variability properties of low-mass active galactic nuclei

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dc.creator Ludlam, R. M.
dc.creator Cackett, E. M.
dc.creator Gultekin, K.
dc.creator Fabian, A. C.
dc.creator Gallo, Luigi C.
dc.creator Miniutti, G.
dc.date.accessioned 2017-05-30T16:16:14Z
dc.date.available 2017-05-30T16:16:14Z
dc.date.issued 2015-03
dc.identifier.issn 0035-8711
dc.identifier.uri http://library2.smu.ca/handle/01/26988
dc.description Publisher's version/PDF en_CA
dc.description.abstract We study the X-ray properties of a sample of 14 optically selected low-mass active galactic nuclei (AGN) whose masses lie within the range 10[superscript 5]–2 × 10[superscript 6] M[subscript circled dot] with XMM–Newton. Only six of these low-mass AGN have previously been studied with sufficient quality X-ray data, thus, we have more than double the number of low-mass AGN observed by XMM–Newton with the addition of our sample. We analyse their X-ray spectral properties and variability and compare the results to their more massive counterparts. The presence of a soft X-ray excess is detectable in all five objects which were not background dominated at 2–3 keV. Combined with previous studies, this gives a total of eight low-mass AGN with a soft excess. The low-mass AGN exhibit rapid, short-term variability (hundreds to thousands of seconds) and long-term variability (months to years). There is a well-known anticorrelation between black hole mass and variability amplitude (normalized excess variance). Comparing our sample of low-mass AGN with this relation we find that all of our sample lie below an extrapolation of the linear relation. Such a flattening of the relation at low masses (below ∼10[superscript 6] M[subscript circled dot]) is expected if the variability in all AGN follows the same shape power spectrum with a break frequency that is dependent on mass. Finally, we also found two objects that show significant absorption in their X-ray spectrum, indicative of type 2 objects, although they are classified as type 1 AGN based on optical spectra. en_CA
dc.language.iso en en_CA
dc.publisher Oxford University Press en_CA
dc.relation.uri http://dx.doi.org/10.1093/mnras/stu2618
dc.rights This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2015 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
dc.subject.lcsh Active galactic nuclei
dc.subject.lcsh X-ray astronomy
dc.subject.lcsh Black holes (Astronomy)
dc.subject.lcsh X-ray sources, Galactic -- Accretion
dc.title X-ray spectral and variability properties of low-mass active galactic nuclei en_CA
dc.type Text en_CA
dcterms.bibliographicCitation Monthly Notices of the Royal Astronomical Society 447(3), 2112-2122. (2015) en_CA


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This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2015 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
 
Published Version: http://dx.doi.org/10.1093/mnras/stu2618
 
 

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