2010A&A...512A...1M


C.D.S. - SIMBAD4 rel 1.7 - 2021.03.02CET03:24:36

2010A&A...512A...1M - Astronomy and Astrophysics, volume 512, A1-1 (2010/3-1)

J004457+4123 (Sharov21): not a remarkable nova in M31 but a background quasar with a spectacular UV flare.

MEUSINGER H., HENZE M., BIRKLE K., PIETSCH W., WILLIAMS B., HATZIDIMITRIOU D., NESCI R., MANDEL H., ERTEL S., HINZE A. and BERTHOLD T.

Abstract (from CDS):

We announce the discovery of a quasar behind the disk of M31, which was previously classified as a remarkable nova in our neighbour galaxy. It is shown here to be a quasar with a single strong flare where the UV flux has increased by a factor of ∼20. The present paper is primarily aimed at the remarkable outburst of J004457+4123 (Sharov21), with the first part focussed on the optical spectroscopy and the improvement in the photometric database. We exploited the archives of photographic plates and CCD observations from 15 wide-field telescopes and performed targetted new observations. In the second part, we try to fit the flare by models of (1) gravitational microlensing due to a star in M31 and (2) a tidal disruption event (TDE) of a star close to the supermassive black hole of the quasar. Both the optical spectrum and the broad band spectral energy distribution of Sharov21 are shown to be very similar to that of normal, radio-quiet type1 quasars. We present photometric data covering more than a century and resulting in a long-term light curve that is densely sampled over the past five decades. The variability of the quasar is characterized by a ground state with typical fluctuation amplitudes of ∼0.2mag around B∼20.5, superimposed by a singular flare of ∼2yr duration (observer frame) with the maximum at 1992.81. The total energy in the flare is at least three orders of magnitudes higher than the radiated energy of the most luminous supernovae, provided that it comes from an intrinsic process and the energy is radiated isotropically. The profile of the flare light curve is asymmetric showing in particular a sudden increase before the maximum, whereas the decreasing part can be roughly approximated by a t–5/3 power law. Both properties appear to support the standard TDE scenario where a ∼10M giant star was shredded in the tidal field of a ∼2...5x108M black hole. The short fallback time derived from the observed light curve requires an ultra-close encounter where the pericentre of the stellar orbit is deep within the tidal disruption radius. This simple model neglects, however, the influence of the massive accretion disk, as well as general-relativistic effects on the orbit of the tidal debris. Gravitational microlensing probably provides an alternative explanation, although the probability of such a high amplification event is very low.

Abstract Copyright:

Journal keyword(s): quasars: general - quasars: individual: J004457+4123 - galaxies: individual: M31 - gravitational lensing: micro - black hole physics

Simbad objects: 21

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Number of rows : 21

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 [VV2006] J001130.4+005751 QSO 00 11 30.4031864 +00 57 51.876909   18.55 18.16 20.06   ~ 76 0
2 M 110 GiG 00 40 22.0544552438 +41 41 07.496294862   8.92 8.07     ~ 1228 1
3 M 32 IG 00 42 41.825 +40 51 54.61 9.51 9.03 8.08     ~ 2034 2
4 M 31 G 00 42 44.330 +41 16 07.50 4.86 4.36 3.44     ~ 11207 1
5 GLG 43 Rad 00 44 53.290 +41 24 19.76           ~ 2 0
6 LGGS J004457.94+412343.9 QSO 00 44 58.10 +41 23 44.4 19.489 20.371 19.914 19.554 18.989 ~ 11 0
7 GLG 45 Rad 00 45 01.420 +41 21 59.65           ~ 2 0
8 GLG 50 Rad 00 45 01.920 +41 24 52.80           ~ 2 0
9 GLG 51 Rad 00 45 05.800 +41 22 43.49           ~ 2 0
10 SN 2006gy SN* 03 17 27.06 +41 24 19.5       14.20   SNIIn 297 1
11 QSO J0854+2006 BLL 08 54 48.8749311881 +20 06 30.642936668   15.91 15.43 15.56   ~ 2060 1
12 2MASX J13402284+2740585 Sy1 13 40 22.8664077077 +27 40 58.506485263   19.32 18.66     ~ 22 1
13 M 3 GlC 13 42 11.62 +28 22 38.2     6.39     ~ 2298 0
14 NGC 5548 Sy1 14 17 59.5401093128 +25 08 12.600227883   14.35 13.73     ~ 2445 0
15 M 92 GlC 17 17 07.39 +43 08 09.4     6.52     ~ 1932 0
16 GAL 000.0+00.0 gam 17 45 39.60213 -29 00 22.0000           ~ 11999 0
17 SS 433 HXB 19 11 49.5645897700 +04 58 57.824087535   16.3 13.0     A7Ib: 1958 4
18 2SLAQ J211817.40+001316.8 Sy1 21 18 17.3985422496 +00 13 16.809685220   18.7 19.29 18.6   ~ 65 1
19 BD+28 4211 HS* 21 51 11.0220905905 +28 51 50.366090892 8.922 10.25 10.58 10.656 10.831 sdO2VIIIHe5 744 0
20 NAME BL Lac BLL 22 02 43.2913773726 +42 16 39.978417860   15.66 14.72     ~ 2037 1
21 NAME Local Group GrG ~ ~           ~ 7181 0

    Equat.    Gal    SGal    Ecl

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2021.03.02-03:24:36

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