2023ApJ...955....3G


Query : 2023ApJ...955....3G

2023ApJ...955....3G - Astrophys. J., 955, 3 (2023/September-3)

A Reemerging Bright Soft X-Ray State of the Changing-look Active Galactic Nucleus 1ES 1927+654: A Multiwavelength View.

GHOSH R., LAHA S., MEYER E., ROYCHOWDHURY A., YANG X., ACOSTA-PULIDO J.A., RAKSHIT S., PANDEY S., GONZALEZ J.B., BEHAR E., GALLO L.C., PANESSA F., BIANCHI S., LA FRANCA F., SCEPI N., BEGELMAN M.C., LONGINOTTI A.L., LUSSO E., OATES S., NICHOLL M., CENKO S.B., O'CONNOR B., HAMMERSTEIN E., JOSE J., GABANYI K.E., RICCI F. and CHATTOPADHYAY S.

Abstract (from CDS):

1ES1927+654 is a nearby active galactic nucleus (AGN) that has shown an enigmatic outburst in optical/UV followed by X-rays, exhibiting strange variability patterns at timescales of months to years. Here we report the unusual X-ray, UV, and radio variability of the source in its postflare state (2022 January-2023 May). First, we detect an increase in the soft X-ray (0.3-2 keV) flux from 2022 May to 2023 May by almost a factor of 5, which we call the bright soft state. The hard X-ray 2-10 keV flux increased by a factor of 2, while the UV flux density did not show any significant changes (≤30%) in the same period. The integrated energy pumped into the soft and hard X-rays during this period of 11 months is ∼3.57 × 1050 erg and 5.9 × 1049 erg, respectively. From the energetics, it is evident that whatever is producing the soft excess (SE) is pumping out more energy than either the UV or hard X-ray source. Since the energy source presumably is ultimately the accretion of matter onto the supermassive black hole, the SE-emitting region must be receiving the majority of this energy. In addition, the source does not follow the typical disk-corona relation found in AGNs, neither in the initial flare (from 2017 to 2019) nor in the current bright soft state (2022-2023). We found that the core (<1 pc) radio emission at 5 GHz gradually increased until 2022 March, but showed a dip in 2022 August. The Güdel-Benz relation (Lradio/LX–ray ∼ 10–5), however, is still within the expected range for radio-quiet AGNs, and further follow-up radio observations are currently being undertaken.

Abstract Copyright: © 2023. The Author(s). Published by the American Astronomical Society.

Journal keyword(s): Active galactic nuclei - X-ray active galactic nuclei - Seyfert galaxies

Simbad objects: 10

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Number of rows : 10
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026
#notes
1 NGC 863 Sy2 02 14 33.5604714720 -00 46 00.181845336   14.48 13.81 17.9   ~ 770 0
2 NGC 1507 H2G 04 04 27.21 -02 11 18.9   12.8 12.36 13.0 12.9 ~ 138 0
3 NGC 1566 Sy1 04 20 00.3968473248 -54 56 16.624708764 10.29 10.19 9.73 9.21 10.1 ~ 1051 2
4 BD+52 913 WD* 05 05 30.6180977592 +52 49 51.919301604 10.25 11.44 11.69 11.93 12.108 DA.8 1153 0
5 Z 119-12 SyG 08 13 16.9505119752 +22 38 53.905852212           ~ 156 0
6 NGC 3516 Sy1 11 06 47.4632200800 +72 34 07.298374656   13.12 12.40     ~ 1638 0
7 AT 2018zf SN* 19 27 19.485 +65 33 54.37           ~ 24 0
8 RX J1927.3+6533 Sy2 19 27 19.5393064368 +65 33 54.335877408     15.4     ~ 147 0
9 ASASSN -15oi SN* 20 39 09.096 -30 45 20.71           ~ 184 0
10 BD+28 4211 HS* 21 51 11.0221915656 +28 51 50.367627468 8.922 10.25 10.58 10.656 10.831 sdO2VIIIHe5 837 0

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