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

Gezari, Suvi; Hung, T.; Cenko, S. Bradley; Blagorodnova, N.; Yan, Lin; Kulkarni, S. R.; Mooley, K. P.; Kong, Albert; Cantwell, T.; Yu, Po-Chieh; Cao, Y.; Fremling, C.; Neill, James D.; Ngeow, Chow-Choong; Nugent, P.; Woźniak, P. R.

doi:10.3847/1538-4357/835/2/144

Cited by 137 publications

(190 citation statements)

References 98 publications

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“…The hypothesis that flares from active galactic nuclei (AGN) are TDF impostors perhaps has the most observational support because relatively rapid changes of AGN luminosity and spectral type have been observed (Storchi-Bergmann et al 1993;Shappee et al 2014;LaMassa et al 2015;Gezari et al 2017). While the observed properties of these changing-look AGN are different from candidate TDFs (Ruan et al 2016;MacLeod et al 2016), their existence demonstrates that the luminosity of AGN can increase beyond what is expected from the power spectrum that accurately describes the light curves of mundane AGN (MacLeod et al 2012;Graham et al 2017).…”

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confidence: 99%

On the Mass and Luminosity Functions of Tidal Disruption Flares: Rate Suppression due to Black Hole Event Horizons

Velzen

2018

ApJ

127

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The tidal disruption of a star by a massive black hole is expected to yield a luminous flare of thermal emission. About two dozen of these stellar tidal disruption flares (TDFs) may have been detected in optical transient surveys. However, explaining the observed properties of these events within the tidal disruption paradigm is not yet possible. This theoretical ambiguity has led some authors to suggest that optical TDFs are due to a different process, such as a nuclear supernova or accretion disk instabilities. Here we present a test of a fundamental prediction of the tidal disruption event scenario: a suppression of the flare rate due to the direct capture of stars by the black hole. Using a recently compiled sample of candidate TDFs with black hole mass measurements, plus a careful treatment of selection effects in this flux-limited sample, we confirm that the dearth of observed TDFs from high-mass black holes is statistically significant. All the TDF impostor models we consider fail to explain the observed mass function; the only scenario that fits the data is a suppression of the rate due to direct captures. We find that this suppression can explain the low volumetric rate of the luminous TDF candidate ASASSN-15lh, thus supporting the hypothesis that this flare belongs to the TDF family. Our work is the first to present the optical TDF luminosity function. A steep power law is required to explain the observed rest-frame g-band luminosity, dN/dL g ∝ L −2.5 g . The mean event rate of the flares in our sample is ≈ 1 × 10 −4 galaxy −1 yr −1 , consistent with the theoretically expected tidal disruption rate.

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confidence: 99%

On the Mass and Luminosity Functions of Tidal Disruption Flares: Rate Suppression due to Black Hole Event Horizons

Velzen

2018

ApJ

127

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“…We use this source as a touchstone to discuss physical models of abrupt quasar fading, a subject that has received considerable attention recently thanks to the growing ranks of wide-area ground-based optical surveys (e.g., LaMassa et al 2015;Macleod et al 2016;Ruan et al 2016aRuan et al , 2016bRunnoe et al 2016;Gezari et al 2017;Sheng et al 2017;Yang et al 2018;Assef et al 2018;Ross et al 2018). In particular, we emphasize the unique value of multiepoch mid-IR photometry to test and exclude models that attempt to ascribe large changes in quasar luminosities to obscuration by an intervening cloud.…”

Section: Discussionmentioning

confidence: 99%

A Mid-IR Selected Changing-look Quasar and Physical Scenarios for Abrupt AGN Fading

Stern

McKernan

Graham

et al. 2018

ApJ

159

185

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We report a new changing-look quasar, WISEJ105203.55+151929.5 at z=0.303, found by identifying highly mid-IR-variable quasars in the Wide-field Infrared Survey Explorer(WISE)/Near-Earth Object WISE Reactivation (NEOWISE) data stream. Compared to multiepoch mid-IR photometry of a large sample of SDSS-confirmed quasars, WISEJ1052+1519is an extreme photometric outlier, fading by more than a factor of two at 3.4 and 4.6 μm since 2009. Swift target-of-opportunity observations in 2017 show even stronger fading in the soft X-rays compared to the ROSAT detection of this source in 1995, with at least a factor of 15 decrease. We obtained secondepoch spectroscopy with the Palomar telescope in 2017 that, when compared with the 2006 archival SDSS spectrum, reveals that the broad Hβ emission has vanished and that the quasar has become significantly redder. The two most likely interpretations for this dramatic change are source fading or obscuration, where the latter is strongly disfavored by the mid-IR data. We discuss various physical scenarios that could cause such changes in the quasar luminosity over this timescale, and favor changes in the innermost regions of the accretion disk that occur on the thermal and heating/cooling front timescales. We discuss possible physical triggers that could cause these changes, and predict the multiwavelength signatures that could distinguish these physical scenarios.

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“…Significant spectral changes are found for instance in SDSS J1011+5442 (Runnoe et al 2016), J01264-0839 and J2336+00172 , and iPTF 16bco (Gezari et al 2017). New monitoring projects now actively hunt for more of these unique objects (MacLeod et al 2016).…”

Section: Introductionmentioning

confidence: 99%

The Close AGN Reference Survey (CARS)

Krumpe

Tremblay

Urrutia

et al. 2017

A&A

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After changing optical AGN type from 1.9 to 1 in 1984, the AGN Mrk 1018 recently reverted back to its type 1.9 state. Our ongoing monitoring now reveals that the AGN has halted its dramatic dimming, reaching a minimum around October 2016. The minimum was followed by an outburst rising with ∼0.25 U-band mag/month. The rebrightening lasted at least until February 2017, as confirmed by joint Chandra and Hubble observations. Monitoring was resumed in July 2017 after the source emerged from sunblock, at which point the AGN was found only ∼0.4 mag brighter than its minimum. The intermittent outburst was accompanied by the appearance of a red wing asymmetry in broad-line shape, indicative of an inhomogeneous broad-line region. The current flickering brightness of Mrk 1018 following its rapid fading either suggests that the source has reignited, remains variable at a low level, or may continue dimming over the next few years. Distinguishing between these possibilities requires continuous multiwavelength monitoring.

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

Cited by 137 publications

References 98 publications

On the Mass and Luminosity Functions of Tidal Disruption Flares: Rate Suppression due to Black Hole Event Horizons

On the Mass and Luminosity Functions of Tidal Disruption Flares: Rate Suppression due to Black Hole Event Horizons

A Mid-IR Selected Changing-look Quasar and Physical Scenarios for Abrupt AGN Fading

The Close AGN Reference Survey (CARS)

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