Broad-band X-ray observations of the 2018 outburst of the changing-look active galactic nucleus NGC 1566

Author:

Jana Arghajit1ORCID,Kumari Neeraj12ORCID,Nandi Prantik3,Naik Sachindra1ORCID,Chatterjee Arka45ORCID,Jaisawal Gaurava K6ORCID,Hayasaki Kimitake5,Ricci Claudio78ORCID

Affiliation:

1. Astronomy & Astrophysics Division, Physical Research Laboratory, Navrangpura, Ahmedabad, 380009, India

2. Department of Physics, Indian Institute of Technology, Gandhinagar-382355, Gujarat, India

3. Department of Astrophysics and Cosmology, S. N. Bose National Centre for Basic Science, Block-JD, Sector-III, Salt Lake, Kolkata, 700106, India

4. Department of Physics, School of Natural Sciences, UNIST, Ulsan, 44919, Republic of Korea

5. Department of Astronomy and Space Science, Chungbuk National University, Cheongju, 361-763, Republic of Korea

6. National Space Institute, Technical University of Denmark, Elektrovej 327-328, DK-2800 Lyngby, Denmark

7. Núcleo de Astronomía de la Facultad de Ingeniería, Universidad Diego Portales, Av. Ejército Libertador 441, Santiago, Chile

8. Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871, People’s Republic of China

Abstract

ABSTRACT We study the nature of the changing-look active galactic nucleus NGC 1566 during its 2018 June outburst. During the outburst, the X-ray intensity of the source rises up to ∼25–30 times compared to its quiescent state intensity. We perform timing and spectral analysis of the source during pre-outburst, outburst, and post-outburst epochs using semisimultaneous observations with the XMM–Newton, Nuclear Spectroscopic Telescope Array(NuSTAR), and Neil Gehrels Swift Observatories. We calculate variance, normalized variance, and fractional rms amplitude in different energy bands to study the variability. The broad-band 0.5–70 keV spectra are fitted with phenomenological models, as well as physical models. A strong soft X-ray excess is detected in the spectra during the outburst. The soft-excess emission is found to be complex and could originate in the warm Comptonizing region in the inner accretion disc. We find that the increase in the accretion rate is responsible for the sudden rise in luminosity. This is supported by the ‘q’-shape of the hardness-intensity diagram that is generally found in outbursting black hole X-ray binaries. From our analysis, we find that NGC 1566 most likely harbours a low-spinning black hole with the spin parameter a* ∼ 0.2. We also discuss a scenario where the central core of NGC 1566 could be a merging supermassive black hole.

Funder

CSIR

National Research Foundation of Korea

Kyoto University

Astrophysics Science Division

NASA

GSFC

Smithsonian Astrophysical Observatory

California Institute of Technology

Publisher

Oxford University Press (OUP)

Subject

Space and Planetary Science,Astronomy and Astrophysics

Cited by 12 articles. 订阅此论文施引文献 订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献

1. Magnetized Accretion Disks with Outflows for Changing-look AGNs;The Astrophysical Journal;2023-11-20

2. Coronal properties of low-accreting AGNs using Swift, XMMNewton, and NuSTAR observations;Monthly Notices of the Royal Astronomical Society;2023-07-17

3. Multiple flares in the changing-look AGN NGC 5273;Monthly Notices of the Royal Astronomical Society;2023-03-11

4. The changing-look AGN NGC 1566 in quiescence with XMM-Newton: a nuclear starburst and an AGN competing in power?;Monthly Notices of the Royal Astronomical Society;2022-05-12

5. Thermal Comptonization in a Changing Corona in the Changing-look Active Galaxy NGC 1566;The Astrophysical Journal;2022-05-01

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