NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-06-25 T17:01:20 PDT
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For refcode 2015MNRAS.447.2112L:
Retrieve 40 NED objects in this reference.
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NED Abstract

Copyright by Royal Astronomical Society. 2015MNRAS.447.2112L X-ray spectral and variability properties of low-mass active galactic nuclei Ludlam, R. M.; Cackett, E. M.; Gultekin, K.; Fabian, A. C.; Gallo, L.; Miniutti, G. 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 10^5^-2 x 10^6^ M_sun_ 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 ~10^6^ M_sun_) 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. Key words: accretion, accretion discs, galaxies: active, galaxies: Seyfert, X-rays: galaxies
Retrieve 40 NED objects in this reference.
Please click here for ADS abstract

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