Evolution of tidal disruption candidates  
	 discovered by <i>XMM-Newton</i>

Esquej, P.; Saxton, R. D.; Komossa, S.; Read, A. M.; Freyberg, M. J.; Hasinger, G.; García-Hernández, D. A.; Lü, H.; Zaurín, J. Rodríguez; Sánchez‐Portal, M.; Zhou, Hongyan

doi:10.1051/0004-6361:200810110

Cited by 168 publications

(228 citation statements)

References 53 publications

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“…The characteristics of the flare are therefore consistent with previous cases of candidate tidal disruption events (see e.g. Komossa et al 2004;Esquej et al 2008) and with theoretical predictions (Rees 1990;Lodato et al 2008). The mass of the BH should be not much higher than ∼10 8 M to disrupt a Sun-like star outside the Schwarzschild radius and to allow the onset of accretion.…”

Section: Discussionsupporting

confidence: 90%

A candidate tidal disruption event in the Galaxy cluster Abell 3571

Cappelluti

Ajello

Rebusco

et al. 2009

A&A

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Context. Tidal disruption events are possible sources of temporary nuclear activity in galactic nuclei and can be considered as good indicators of the existence of supermassive black holes in the centers of galaxies. Aims. A new X-ray source has been detected serendipitously with ROSAT in a PSPC pointed observation of the galaxy cluster A3571. Given the strong flux decay of the object in subsequent detections, the tidal disruption scenario is investigated as a possible explanation of the event. Methods. We followed the evolution of the X-ray transient with ROSAT, XMM-Newton and Chandra for a total period of ∼13 years. We also obtained 7-band optical/NIR photometry with GROND at the ESO/MPI 2.2 m telescope. Results. We report a very large decay of the X-ray flux of the ROSAT source identified with the galaxy LEDA 095953, a member of the cluster Abell 3571. We measured a maximum 0.3−2.4 keV luminosity Log (L X ) = 42.8 erg s −1 . The high state of the source lasted at least 150 ks; afterwards L X declined as ∼t −2 . The spectrum of the brightest epoch is consistent with a black body with temperature kT ∼ 0.12 keV. Conclusions. The total energy released by this event in 10 yr was estimated to be Δ E > 2 × 10 50 erg. We interpret this event as a tidal disruption of a solar type star by the central supermassive black hole (i.e. ∼10 7 M ) of the galaxy.

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Section: Discussionsupporting

confidence: 90%

A candidate tidal disruption event in the Galaxy cluster Abell 3571

Cappelluti

Ajello

Rebusco

et al. 2009

A&A

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“…The X-ray spectrum of SDSS J1201+30 is not the thermal radiation expected in the early stages of a disruption, if the density is sufficient to thermalise the photons (Rees 1988) and neither is it the typical signature of an accretion disc, seen in the late stages of several other TDE candidates Vaughan et al 2004;Esquej et al 2008). It is best fit with a Bremsstrahlung or broken power-law model which becomes softer with time and/or reducing flux.…”

Section: Tidal Disruptionmentioning

confidence: 98%

A tidal disruption-like X-ray flare from the quiescent galaxy SDSS J120136.02+300305.5

Saxton

Read

Esquej

et al. 2012

A&A

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Aims. The study of tidal disruption flares from galactic nuclei has historically been hampered by a lack of high quality spectral observations taken around the peak of the outburst. Here we introduce the first results from a program designed to identify tidal disruption events at their peak by making near-real-time comparisons of the flux seen in XMM-Newton slew sources with that seen in ROSAT. Methods. Flaring extragalactic sources, which do not appear to be AGN, are monitored with Swift and XMM-Newton to track their temporal and spectral evolution. Timely optical observations are made to monitor the reaction of circumnuclear material to the X-ray flare.Results. SDSS J120136.02+300305.5 was detected in an XMM-Newton slew from June 2010 with a flux 56 times higher than an upper limit from ROSAT, corresponding to L X ∼ 3 × 10 44 erg s −1 . It has the optical spectrum of a quiescent galaxy (z = 0.146). Overall the X-ray flux has evolved consistently with the canonical t −5/3 model, expected for returning stellar debris, fading by a factor ∼300 over 300 days. In detail the source is very variable and became invisible to Swift between 27 and 48 days after discovery, perhaps due to self-absorption. The X-ray spectrum is soft but is not the expected tail of optically thick thermal emission. It may be fit with a Bremsstrahlung or double-power-law model and is seen to soften with time and declining flux. Optical spectra taken 12 days and 11 months after discovery indicate a deficit of material in the broad line and coronal line regions of this galaxy, while a deep radio non-detection implies that a jet was not launched during this event.

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“…Until now, about a dozen TDE candidates in non-AGN galaxies have been found from X-ray surveys (Komossa 2002;Komossa et al 2009;Esquej 2007Esquej , 2008Cappelluti et al 2009) and also in the UV/Optical (Renzini et al 1995;Gezari et al 2006Gezari et al , 2008. None of the events detected so far were found to be related to a high-luminosity AGN.…”

Section: A Stellar Tidal Disruption Event?mentioning

confidence: 99%

J004457+4123 (Sharov 21): not a remarkable nova in M 31 but a background quasar with a spectacular UV flare

Meusinger¹,

Henze

Birkle

et al. 2010

A&A

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Aims. We announce the discovery of a quasar behind the disk of M 31, 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 (Sharov 21), with the first part focussed on the optical spectroscopy and the improvement in the photometric database. Methods. 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 M 31 and (2) a tidal disruption event (TDE) of a star close to the supermassive black hole of the quasar. Results. Both the optical spectrum and the broad band spectral energy distribution of Sharov 21 are shown to be very similar to that of normal, radio-quiet type 1 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 ∼0.2 mag aroundB ∼ 20.5, superimposed by a singular flare of ∼2 yr 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 ∼10 M giant star was shredded in the tidal field of a ∼2 . . . 5 × 10 8 M 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.

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Evolution of tidal disruption candidates discovered by XMM-Newton

Cited by 168 publications

References 53 publications

A candidate tidal disruption event in the Galaxy cluster Abell 3571

A candidate tidal disruption event in the Galaxy cluster Abell 3571

A tidal disruption-like X-ray flare from the quiescent galaxy SDSS J120136.02+300305.5

J004457+4123 (Sharov 21): not a remarkable nova in M 31 but a background quasar with a spectacular UV flare

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