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The destruction and recreation of the X-ray corona in a changing-look active galactic nucleus

The destruction and recreation of the X-ray corona in a changing-look active galactic nucleus
The destruction and recreation of the X-ray corona in a changing-look active galactic nucleus

We present the drastic transformation of the X-ray properties of the active galactic nucleus (AGN) 1ES 1927+654, following a changing-look event. After the optical/ultraviolet outburst the power-law component, produced in the X-ray corona, disappeared, and the spectrum of 1ES 1927+65 instead became dominated by a blackbody component (kT ∼ 80-120 eV). This implies that the X-ray corona, ubiquitously found in AGNs, was destroyed in the event. Our dense ∼450 days long X-ray monitoring shows that the source is extremely variable in the X-ray band. On long timescales the source varies up to ∼4 dex in ∼100 days, while on short timescales up to ∼2 dex in ∼8 hr. The luminosity of the source is found to first show a strong dip down to ∼1040 erg s-1 , and then a constant increase in luminosity to levels exceeding the pre-outburst level ⪆300 days after the optical event detection, rising up asymptotically to ∼2 × 1044 erg s-1. As the X-ray luminosity of the source increases, the X-ray corona is recreated, and a very steep power-law component (Γ ≃ 3) reappears, and dominates the emission for 0.3-2 keV luminosities ≳ 1043.7 erg s-1, ∼300 days after the beginning of the event. We discuss possible origins of this event, and speculate that our observations could be explained by the interaction between the accretion flow and debris from a tidally disrupted star. Our results show that changing-look events can be associated with dramatic and rapid transformations of the innermost regions of accreting supermassive black holes.

2041-8205
Altamirano, Diego
d5ccdb09-0b71-4303-9538-05b467be075b
Altamirano, Diego
d5ccdb09-0b71-4303-9538-05b467be075b

Altamirano, Diego (2020) The destruction and recreation of the X-ray corona in a changing-look active galactic nucleus. Astrophysical Journal Letters, 898 (1), [L1]. (doi:10.3847/2041-8213/ab91a1).

Record type: Article

Abstract

We present the drastic transformation of the X-ray properties of the active galactic nucleus (AGN) 1ES 1927+654, following a changing-look event. After the optical/ultraviolet outburst the power-law component, produced in the X-ray corona, disappeared, and the spectrum of 1ES 1927+65 instead became dominated by a blackbody component (kT ∼ 80-120 eV). This implies that the X-ray corona, ubiquitously found in AGNs, was destroyed in the event. Our dense ∼450 days long X-ray monitoring shows that the source is extremely variable in the X-ray band. On long timescales the source varies up to ∼4 dex in ∼100 days, while on short timescales up to ∼2 dex in ∼8 hr. The luminosity of the source is found to first show a strong dip down to ∼1040 erg s-1 , and then a constant increase in luminosity to levels exceeding the pre-outburst level ⪆300 days after the optical event detection, rising up asymptotically to ∼2 × 1044 erg s-1. As the X-ray luminosity of the source increases, the X-ray corona is recreated, and a very steep power-law component (Γ ≃ 3) reappears, and dominates the emission for 0.3-2 keV luminosities ≳ 1043.7 erg s-1, ∼300 days after the beginning of the event. We discuss possible origins of this event, and speculate that our observations could be explained by the interaction between the accretion flow and debris from a tidally disrupted star. Our results show that changing-look events can be associated with dramatic and rapid transformations of the innermost regions of accreting supermassive black holes.

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More information

Accepted/In Press date: 8 May 2020
e-pub ahead of print date: 16 July 2020
Published date: 20 July 2020
Additional Information: arxiv is am

Identifiers

Local EPrints ID: 443482
URI: http://eprints.soton.ac.uk/id/eprint/443482
ISSN: 2041-8205
PURE UUID: 2954024a-64d4-4450-ab12-33982e4937ef
ORCID for Diego Altamirano: ORCID iD orcid.org/0000-0002-3422-0074

Catalogue record

Date deposited: 26 Aug 2020 16:36
Last modified: 26 Nov 2021 03:02

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