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Detection of the high energy cut-off from the Seyfert 1.5 galaxy NGC 5273

Pahari, Mayukh and McHardy, I. M. and Mallick, Labani and Dewangan, G. C. and Misra, R. (2017) Detection of the high energy cut-off from the Seyfert 1.5 galaxy NGC 5273. Monthly Notices of the Royal Astronomical Society, 470 (3). pp. 3239-3248. ISSN 0035-8711. doi:10.1093/mnras/stx1455.

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We perform the NuSTAR and Swift/XRT joint energy spectral fitting of simultaneous observations from the broad-line Seyfert 1.5 galaxy NGC 5273. When fitted with the combination of an exponential cut-off power law and a reflection model, a high-energy cut-off is detected at 143 ^(+96)_(−40) keV with 2σ significance. Existence of such cut-off is also consistent with the observed Comptonizing electron temperature when fitted with a Comptonization model independently. We observe a moderate hard X-ray variability of the source over the time-scale of ∼12 yr using INTEGRAL/ISGRI observations in the energy range of 20–100 keV. When the hard-band count rate (6–20 keV) is plotted against the soft-band count rate (3–6 keV), a hard offset is observed. Our results indicate that the cut-off energy may not correlate with the coronal X-ray luminosity in a simple manner. Similarities in parameters that describe coronal properties indicate that the coronal structure of NGC 5273 may be similar to that of the broad-line radio galaxy 3C 390.3 and another galaxy MCG-5-23-16, where the coronal plasma is dominated by electrons, rather than electron–positron pairs. Therefore, the coronal cooling is equally efficient to the heating mechanism keeping the cut-off energy at low even at the low accretion rate.

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Additional Information:© 2017 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2017 June 8. Received 2017 May 31; in original form 2017 March 5. Published: 12 June 2017. We thank the referee for constructive comments and suggestions. We are thankful to NuSTAR team for making data publicly available. This research has made use of the NuSTAR Data Analysis Software (NuSTARDAS) jointly developed by the ASI Science Data Center (ASDC, Italy) and the California Institute of Technology (USA). INTEGRAL/ISGRI and Swift/XRT data obtained through the High Energy Astrophysics Science Archive Research Center online service were provided by the NASA/Goddard Space Flight Center.
Subject Keywords:accretion, accretion disc – black hole physics – galaxies: individual: NGC 5273 – galaxies: Seyfert –X-rays: galaxies
Issue or Number:3
Record Number:CaltechAUTHORS:20170612-081242471
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Official Citation:Mayukh Pahari, I. M. MᶜHardy, Labani Mallick, G. C. Dewangan, R. Misra; Detection of the high-energy cut-off from the Seyfert 1.5 galaxy NGC 5273, Monthly Notices of the Royal Astronomical Society, Volume 470, Issue 3, 21 September 2017, Pages 3239–3248,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:78086
Deposited By: Joy Painter
Deposited On:12 Jun 2017 16:12
Last Modified:15 Nov 2021 17:36

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