Flows of X-ray gas reveal the disruption of a star by a massive black hole

Miller, J. M.; Kaastra, J. S.; Miller, M. Coleman; Reynolds, M. T.; Brown, Gordon G.; Cenko, S. B.; Drake, J. J.; Gezari, Suvi; Guillochon, James; Gültekin, Kayhan; Irwin, Jimmy A.; Levan, A. J.; Maitra, D.; Maksym, W. Peter; Mushotzky, R. F.; O’Brien, P. T.; Paerels, F.; Plaa, J. de; Ramírez-Ruiz, E.; Strohmayer, Tod E.; Tanvir, N. R.

doi:10.1038/nature15708

Cited by 164 publications

(155 citation statements)

References 38 publications

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“…Furthermore, while the relativistic Swift events were highly super-Eddington, the peak accretion rate inferred from X-ray observations of XMMSL1 J0740−85 is mildly sub-Eddington (Saxton et al 2016). This is also similar to ASASSN-14li, where modeling of the X-ray, UV, and optical emission showed that this event was at most only mildly super-Eddington (Miller et al 2015;Holoien et al 2016;Alexander et al 2016).…”

Section: Discussionsupporting

confidence: 61%

Radio Observations of the Tidal Disruption Event XMMSL1 J0740–85

Alexander

Wieringa

Berger

et al. 2017

ApJ

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We present radio observations of the tidal disruption event candidate (TDE) XMMSL1 J0740−85 spanning 592 to 875 d post X-ray discovery. We detect radio emission that fades from an initial peak flux density at 1.6 GHz of 1.19 ± 0.06 mJy to 0.65 ± 0.06 mJy suggesting an association with the TDE. This makes XMMSL1 J0740−85 at d = 75 Mpc the nearest TDE with detected radio emission to date and only the fifth TDE with radio emission overall. The observed radio luminosity rules out a powerful relativistic jet like that seen in the relativistic TDE Swift J1644+57. Instead we infer from an equipartition analysis that the radio emission most likely arises from a non-relativistic outflow similar to that seen in the nearby TDE ASASSN-14li, with a velocity of about 10 4 km s −1 and a kinetic energy of about 10 48 erg, expanding into a medium with a density of about 10 2 cm −3 . Alternatively, the radio emission could arise from a weak initially-relativistic but decelerated jet with an energy of ∼ 2 × 10 50 erg, or (for an extreme disruption geometry) from the unbound debris. The radio data for XMMSL1 J0740−85 continues to support the previous suggestion of a bimodal distribution of common non-relativistic isotropic outflows and rare relativistic jets in TDEs (in analogy with the relation between Type Ib/c supernovae and long-duration gamma-ray bursts). The radio data also provide a new measurement of the circumnuclear density on a sub-parsec scale around an extragalactic supermassive black hole.

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Section: Discussionsupporting

confidence: 61%

Radio Observations of the Tidal Disruption Event XMMSL1 J0740–85

Alexander

Wieringa

Berger

et al. 2017

ApJ

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“…Even though these estimates are based on small numbers of events, they are difficult to reconcile with a model where the majority of X-ray events are invisible due to a thick absorber. Furthermore, strong two-temperature soft X-ray and optical emission has been observed simultaneously from the well-monitored TDE, ASSASN-14li, implying that our view to the centre is rather unobscured, apart from a highly-ionised, slowly-expanding, screen A&A 598, A29 (2017) of material with a column of ∼10 23 cm −2 (Miller et al 2015;Cenko et al 2016). Finally, the exceptional X-ray softness of the first identified TDEs strongly argues against large amounts of obscuring material (e.g.…”

Section: Introductionmentioning

confidence: 99%

XMMSL1 J074008.2-853927: a tidal disruption event with thermal and non-thermal components

Saxton

Read

Komossa

et al. 2017

A&A

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Aims. We study X-ray bright tidal disruption events (TDE), close to the peak of their emission, with the intention of understanding the evolution of their light curves and spectra. Methods. Candidate TDE are identified by searching for soft X-ray flares from non-active galaxies in recent XMM-Newton slew data. Results. In April 2014, X-ray emission was detected from the galaxy XMMSL1 J074008.2-853927 (a.k.a. 2MASX 07400785-8539307), a factor 20 times higher than an upper limit from 20 years earlier. Both the X-ray and UV flux subsequently fell, by factors of 70 and 12 respectively. The bolometric luminosity peaked at L bol ∼ 2 × 10 44 ergs s −1 with a spectrum that may be modelled with thermal emission in the UV band, a power-law with Γ ∼ 2 dominating in the X-ray band above 2 keV and a soft X-ray excess with an effective temperature of ∼86 eV. Rapid variability locates the X-ray emission to within <73 R g of the nuclear black hole. Radio emission of flux density ∼1 mJy, peaking at 1.5 GHz was detected 21 months after discovery. Optical spectra indicate that the galaxy, at a distance of 73 Mpc (z = 0.0173), underwent a starburst 2 Gyr ago and is now quiescent. We consider a tidal disruption event to be the most likely cause of the flare. If this proves to be correct then this is a very clean example of a disruption exhibiting both thermal and non-thermal radiation.

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“…We use the observed SED 60 days after the discovery, nearly simultaneous with the UV spectroscopic observation, as the first-order approximation to the input SED. It is composed of two black-bodies: one peaks in the UV with a temperature of 3.55 × 10 4 K and a luminosity of 6.5 × 10 9 L ⊙ ; and the other peaks in the soft X-ray band with a temperature of 6 × 10 5 K (or 50 eV) and a luminosity of about 10 10 L ⊙ erg s −1 (Holoien et al 2016;Miller et al 2015). The ionizing continuum striking the broad line region is likely not exactly the same as the observed SED due to a number of reasons.…”

Section: The Input Sedmentioning

confidence: 99%

The Carbon and Nitrogen Abundance Ratio in the Broad Line Region of Tidal Disruption Events

Yang

Wang

Ferland

et al. 2017

ApJ

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The rest-frame UV spectra of three recent tidal disruption events (TDEs), ASASSN-14li, PTF15af and iPTF16fnl display strong nitrogen emission lines but weak or undetectable carbon lines. In these three objects, the upper limits of the C iii] λ1908/N iii] λ1750 ratio are about two orders of magnitude lower than those of quasars, suggesting a high abundance ratio of [N/C]. With detailed photoionization simulations, we demonstrate that C 2+ and N 2+ are formed in the same zone, so the Ciii]/N iii] ratio depends only moderately on the physical conditions in the gas and weakly on the shape of the ionizing continuum. There are smaller than 0.5 dex variations in the line ratio over wide ranges of gas densities and ionization parameters at a given metallicity. This allows a robust estimate of the relative abundance ratio nitrogen to carbon. We derive a relative abundance ratio of [N/C]> 1.5 for ASASSN-14li, and even higher for PTF15af and iPTF16fnl. This suggests that the broad line region in those TDE sources is made of nitrogen-enhanced core material that falls back at later times. Based on stellar evolution models, the lower limit of the disrupted star should be larger than 0.6M ⊙ . The chemical abundance of the line emitting gas gives a convincing evidence that the flares origin from stellar tidal disruptions. The coincidence of the weakness of the X-ray emission with the strong broad absorption lines in PTF15af, iPTF16fnl and the strong X-ray emission without such lines in ASASSN-li14 are in analogy to quasars with and without broad absorption lines.

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Flows of X-ray gas reveal the disruption of a star by a massive black hole

Cited by 164 publications

References 38 publications

Radio Observations of the Tidal Disruption Event XMMSL1 J0740–85

Radio Observations of the Tidal Disruption Event XMMSL1 J0740–85

XMMSL1 J074008.2-853927: a tidal disruption event with thermal and non-thermal components

The Carbon and Nitrogen Abundance Ratio in the Broad Line Region of Tidal Disruption Events

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