ASASSN-14ae: a tidal disruption event at 200 Mpc

Holoien, T. W. S.; Prieto, J. L.; Bersier, D.; Kochanek, C. S.; Stanek, K. Z.; Shappee, B. J.; Grupe, D.; Basu, U.; Beacom, J. F.; Brimacombe, J.; Brown, J. S.; Davis, A. B.; Jencson, J.; Pojmański, G.; Szczygiel, D.

doi:10.1093/mnras/stu1922

Cited by 262 publications

(343 citation statements)

References 62 publications

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“…(3) The light curve of iPTF 16bco shows a complex shape uncharacteristic of a TDE, with a month-long plateau, followed by a 2-week rise to another plateau. (4) The broad Balmer lines in iPTF 16bco are narrower and stronger than have been observed in TDEs, and iPTF 16bco does not have strong, broad He II l4686, which is characteristic of TDE spectra (Gezari et al 2012;Arcavi et al 2014;Holoien et al 2014Holoien et al , 2016aHoloien et al , 2016b. (5) Finally, the broad-line emission and X-ray continuum in iPTF 16bco are consistent with radio-quiet quasars in the "Eigenvector 1" parameter space: the FWHM velocity width of the broad Hβ line versus the ratio of the equivalent widths of the Fe II λ4570 complex to broad Hβ strength (R Fe II ) (Sulentic et al 2000) favors a change inṀ acc of a preexisting accretion disk, instead of a newly formed debris disk from a TDE.…”

Section: Tidal Disruption Event (Tde)mentioning

confidence: 99%

iPTF Discovery of the Rapid “Turn-on” of a Luminous Quasar

Gezari

Hung

Cenko

et al. 2017

ApJ

135

175

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We present a radio-quiet quasar at z=0.237 discovered "turning on" by the intermediate Palomar Transient Factory (iPTF). The transient, iPTF 16bco, was detected by iPTF in the nucleus of a galaxy with an archival Sloan Digital Sky Survey spectrum with weak narrow-line emission characteristic of a low-ionization nuclear emissionline region (LINER). Our follow-up spectra show the dramatic appearance of broad Balmer lines and a power-law continuum characteristic of a luminous ( » L 10 bol 45 erg s −1 ) type 1 quasar 12 yr later. Our photometric monitoring with PTF from 2009-2012 and serendipitous X-ray observations from the XMM-Newton Slew Survey in 2011 and 2015 constrain the change of state to have occurred less than 500 days before the iPTF detection. An enhanced broad Hα/[O III] λ5007 line ratio in the type 1 state relative to other changing-look quasars also is suggestive of the most rapid change of state yet observed in a quasar. We argue that the >10 increase in Eddington ratio inferred from the brightening in UV and X-ray continuum flux is more likely due to an intrinsic change in the accretion rate of a preexisting accretion disk than an external mechanism such as variable obscuration, microlensing, or the tidal disruption of a star. However, further monitoring will be helpful in better constraining the mechanism driving this change of state. The rapid "turn-on" of the quasar is much shorter than the viscous infall timescale of an accretion disk and requires a disk instability that can develop around a  M 10 8 black hole on timescales less than 1 yr.

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Section: Tidal Disruption Event (Tde)mentioning

confidence: 99%

iPTF Discovery of the Rapid “Turn-on” of a Luminous Quasar

Gezari

Hung

Cenko

et al. 2017

ApJ

135

175

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“…Disruptions closer to the SMBH will have a higher β factor. Observationally, TDE are often considered as black bodies at temperatures generally higher than observed for SNe: from 2 ×10 4 to 5 ×10 4 K (van Velzen et al 2011;Gezari et al 2012;Arcavi et al 2014;Holoien et al 2014). Because of this the K-corrections and the shape of the band-pass play a very important role.…”

Section: Appendix A: Gibis Simulation Toolmentioning

confidence: 99%

“…Since then, the number of TDE discovered in optical surveys has increased rapidly (Gezari et al 2012;Chornock et al 2014;Arcavi et al 2014;Holoien et al 2014). Our study, shows that Gaia could detect a significant number of TDE, substantially increasing the existing sample of this transient class.…”

Section: Introductionmentioning

confidence: 99%

Gaiatransient detection efficiency: hunting for nuclear transients

Blagorodnova

Velzen

Harrison

et al. 2015

Mon. Not. R. Astron. Soc.

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We present a study of the detectability of transient events associated with galaxies for the Gaia European Space Agency astrometric mission. We simulated the on-board detections, and on-ground processing for a mock galaxy catalogue to establish the properties required for the discovery of transient events by Gaia, specifically tidal disruption events (TDEs) and supernovae (SNe). Transients may either be discovered by the on-board detection of a new source or by the brightening of a previously known source. We show that Gaia transients can be identified as new detections on-board for offsets from the host galaxy nucleus of 0.1-0.5 arcsec, depending on magnitude and scanning angle. The Gaia detection system shows no significant loss of SNe at close radial distances to the nucleus. We used the detection efficiencies to predict the number of transients events discovered by Gaia. For a limiting magnitude of 19, we expect around 1300 SNe per year: 65% SN Ia, 28% SN II and 7% SN Ibc, and ∼20 TDEs per year.

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“…Arcavi et al (2014) noted that TDEs show a remarkable diversity in the relative strengths of the hydrogen Hα/Hβ Balmer lines and the HeII 4686Å emission line. In the most extreme cases, the broad HeII emission lines are significantly stronger than the Balmer lines (PS1-10jh, Gezari et al (2012); PTF09ge, Kasliwal et al (2009), , while others show both strong HeII and Balmer emission lines (SDSS J074820.66+471214.6, Wang et al (2012); ASASSN-14ae, Holoien et al (2014); ASASSN-14li, Holoien et al (2016)). There are also some that appear hydrogen dominated (PTF09djl, PTF09axc, Arcavi et al (2014);TDE2, van Velzen et al (2011), and possibly PS1-11af, Chornock et al (2014)).…”

Section: Introductionmentioning

confidence: 98%

Abundance anomalies in tidal disruption events

Kochanek

2016

Mon. Not. R. Astron. Soc.

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The ∼ 10% of tidal disruption events (TDEs) due to stars more massive than M * > ∼ M ⊙ should show abundance anomalies due to stellar evolution in helium, carbon and nitrogen, but not oxygen. Helium is always enhanced, but only by up to ∼ 25% on average because it becomes inaccessible once it is sequestered in the high density core as the star leaves the main sequence. However, portions of the debris associated with the disrupted core of a main sequence star can be enhanced in helium by factors of 2-3 for debris at a common orbital period. These helium abundance variations may be a contributor to the observed diversity of hydrogen and helium line strengths in TDEs. A still more striking anomaly is the rapid enhancement of nitrogen and the depletion of carbon due to the CNO cycle -stars with M * > ∼ M ⊙ quickly show an increase in their average N/C ratio by factors of 3-10. Because low mass stars evolve slowly and high mass stars are rare, TDEs showing high N/C will almost all be due to 1-2M ⊙ stars disrupted on the main sequence. Like helium, portions of the debris will show still larger changes in C and N, and the anomalies decline as the star leaves the main sequence. The enhanced [N/C] abundance ratio of these TDEs provides the first natural explanation for the rare, nitrogen rich quasars and also explains the strong nitrogen emission seen in ultraviolet spectra of ASASSN-14li.

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ASASSN-14ae: a tidal disruption event at 200 Mpc

Cited by 262 publications

References 62 publications

iPTF Discovery of the Rapid “Turn-on” of a Luminous Quasar

iPTF Discovery of the Rapid “Turn-on” of a Luminous Quasar

Gaiatransient detection efficiency: hunting for nuclear transients

Abundance anomalies in tidal disruption events

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