A dust-enshrouded tidal disruption event with a resolved radio jet in a galaxy merger

Mattila, S.; Pérez-Torres, M. Á.; Efstathiou, A.; Mimica, P.; Fraser, M.; Kankare, E.; Alberdi, A.; Aloy, M. Á.; Heikkilä, T.; Jonker, P. G.; Lundqvist, Peter; Martí-Vidal, Iván; Meikle, W. P. S.; Romero-Cañizales, C.; Smartt, S. J.; Tsygankov, Sergey S.; Varenius, Eskil; Alonso‐Herrero, A.; Bondì, M.; Fransson, Claes; Herrero-Illana, R.; Kangas, T.; Kotak, R.; Ramírez-Olivencia, N.; Vaïsänen, P.; Beswick, R. J.; Clements, D. L.; Greimel, R.; Harmanen, J.; Kotilainen, Jari; Nandra, K.; Reynolds, T.; Ryder, S. D.; Walton, N. A.; Wiik, K.; Östlin, Göran

doi:10.1126/science.aao4669

Cited by 166 publications

(197 citation statements)

References 87 publications

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“…More recently, similar X-ray events have been detected with Chandra and XMM-Newton based on dedicated searches or serendipitous discoveries (Esquej et al 2007(Esquej et al , 2008Saxton et al 2012;Auchettl et al 2017). Interestingly, Mattila et al (2018) reported the infrared discovery of a TDE in the merging galaxy pair Arp299, in which the optical emission is strongly obscured by dust. In this case, a expanding relativistic jet produced by the accretion of stellar debris on the SMBH has been clearly detected and resolved by radio VLBI observations.…”

Section: Introductionmentioning

confidence: 72%

Optical follow-up of the tidal disruption event iPTF16fnl: new insights from X-shooter observations

Onori

Cannizzaro

Jonker

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We present the results from Nordic Optical Telescope and X-shooter follow-up campaigns of the tidal disruption event (TDE) iPTF16fnl, covering the first ∼100 days after the transient discovery. We followed the source photometrically until the TDE emission was no longer detected above the host galaxy light. The bolometric luminosity evolution of the TDE is consistent with an exponential decay with e-folding constant t 0 =17.6±0.2 days. The early time spectra of the transient are dominated by broad He ii λ4686, Hβ, Hα and N iii λ4100 emission lines. The latter is known to be produced together with the N iii λ4640 in the Bowen fluorescence mechanism. Thanks to the medium resolution X-shooter spectra we have been able to separate the Bowen blend contribution from the broad He ii emission line. The detection of the Bowen fluorescence lines in iPTF16fnl place this transient among the N-rich TDE subset. In the late-time X-shooter spectra, narrow emission lines of [O iii] and [N ii] originating from the host galaxy are detected, suggesting that the host galaxy harbours a weak AGN in its core. The properties of all broad emission lines evolve with time. The equivalent widths follow an exponential decay compatible with the bolometric luminosity evolution. The full-width a half maximum of the broad lines decline with time and the line profiles develop a narrow core at later epochs. Overall, the optical emission of iPTF16fnl can be explained by being produced in an optically thick region in which high densities favour the Bowen fluorescence mechanism and where multiple electron scatterings are responsible for the line broadening.

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Section: Introductionmentioning

confidence: 72%

Optical follow-up of the tidal disruption event iPTF16fnl: new insights from X-shooter observations

Onori

Cannizzaro

Jonker

et al. 2019

Monthly Notices of the Royal Astronomical Society

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“…The possibility of a weaker nonrelativistic outflow cannot be excluded, but the limit places strict requirements that the radio luminosity from any an outflow does not exceed that seen in nearby events like ASASSN-14li (Alexander et al 2016;van Velzen et al 2016). Further observations will be required to rule out an off-axis jet such as that seen in Arp 299-B (Mattila et al 2018) 2012b). However, most TDEs are not bright in the radio.…”

Section: Radio Observationsmentioning

confidence: 99%

The tidal disruption event AT2017eqx: spectroscopic evolution from hydrogen rich to poor suggests an atmosphere and outflow

Nicholl

Blanchard

Berger

et al. 2019

Monthly Notices of the Royal Astronomical Society

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ABSTRACT We present and analyse a new tidal disruption event (TDE), AT2017eqx at redshift z = 0.1089, discovered by Pan-STARRS and ATLAS. The position of the transient is consistent with the nucleus of its host galaxy; the spectrum shows a persistent blackbody temperature T ≳ 20 000 K with broad H i and He ii emission; and it peaks at a blackbody luminosity of L ≈ 1044 erg s−1. The lines are initially centred at zero velocity, but by 100 d, the H i lines disappear while the He ii develops a blueshift of ≳ 5000 km s−1. Both the early- and late-time morphologies have been seen in other TDEs, but the complete transition between them is unprecedented. The evolution can be explained by combining an extended atmosphere, undergoing slow contraction, with a wind in the polar direction becoming visible at late times. Our observations confirm that a lack of hydrogen a TDE spectrum does not indicate a stripped star, while the proposed model implies that much of the diversity in TDEs may be due to the observer viewing angle. Modelling the light curve suggests AT2017eqx resulted from the complete disruption of a solar-mass star by a black hole of ∼106.3 M⊙. The host is another Balmer-strong absorption galaxy, though fainter and less centrally concentrated than most TDE hosts. Radio limits rule out a relativistic jet, while X-ray limits at 500 d are among the deepest for a TDE at this phase.

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“…This number is made uncertain to the degree that the distribution of stellar orbits near an AGN is systematically different from the center of an inactive galaxy, and that the black hole in a galaxy with an AGN tends to be more massive than a galaxy without one (see also Karas & Šubr 2007;Kennedy et al 2016). Because both TDEs and AGNs vary on timescales of weeks to months, and because a TDE in an AGN presents less contrast against the prior state of the system than a TDE in an inactive galaxy, deciding whether an increase in brightness is due to a TDE or is merely AGN variability is not trivial (Komossa 2015;Kankare et al 2017;Auchettl et al 2018;Trakhtenbrot et al 2019b); indeed, there are a number of cases in which the correct identification of a particular episode of variation is disputed (e.g., Campana et al 2015;Grupe et al 2015;Merloni et al 2015;Saxton et al 2015;Blanchard et al 2017;Lin et al 2017;Wyrzykowski et al 2017;Mattila et al 2018;Shu et al 2018). It is therefore of interest to see if TDEs in AGNs have distinctive observational characteristics that allow us to recognize them more reliably.…”

Section: Introductionmentioning

confidence: 99%

Tidal Disruption Events in Active Galactic Nuclei

Chan

Piran

Krolik

et al. 2019

ApJ

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A fraction of tidal disruption events (TDEs) occur in active galactic nuclei (AGNs) whose black holes possess accretion disks; these TDEs can be confused with common AGN flares. The disruption itself is unaffected by the disk, but the evolution of the bound debris stream is modified by its collision with the disk when it returns to pericenter. The outcome of the collision is largely determined by the ratio of the stream mass current to the azimuthal mass current of the disk rotating underneath the stream footprint, which in turn depends on the mass and luminosity of the AGN. To characterize TDEs in AGNs, we simulated a suite of stream-disk collisions with various mass current ratios. The collision excites shocks in the disk, leading to inflow and energy dissipation orders of magnitude above Eddington; however, much of the radiation is trapped in the inflow and advected into the black hole, so the actual bolometric luminosity may be closer to Eddington. The emergent spectrum may not be thermal, TDE-like, or AGN-like. The rapid inflow causes the disk interior to the impact point to be depleted within a fraction of the mass return time. If the stream is heavy enough to penetrate the disk, part of the outgoing material eventually hits the disk again, dissipating its kinetic energy in the second collision; another part becomes unbound, emitting synchrotron radiation as it shocks with surrounding gas.

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A dust-enshrouded tidal disruption event with a resolved radio jet in a galaxy merger

Cited by 166 publications

References 87 publications

Optical follow-up of the tidal disruption event iPTF16fnl: new insights from X-shooter observations

Optical follow-up of the tidal disruption event iPTF16fnl: new insights from X-shooter observations

The tidal disruption event AT2017eqx: spectroscopic evolution from hydrogen rich to poor suggests an atmosphere and outflow

Tidal Disruption Events in Active Galactic Nuclei

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