scholarly journals Tidal Disruption Events in Active Galactic Nuclei

2019 ◽  
Vol 881 (2) ◽  
pp. 113 ◽  
Author(s):  
Chi-Ho Chan ◽  
Tsvi Piran ◽  
Julian H. Krolik ◽  
Dekel Saban
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Tidal Disruption

scholarly journals Epicyclic oscillations in spinning particle motion around Kerr black hole applied in models fitting the quasi-periodic oscillations observed in microquasars and AGNs

2021 ◽  
Vol 81 (12) ◽  
Author(s):  
Misbah Shahzadi ◽  
Martin Kološ ◽  
Zdeněk Stuchlík ◽  
Yousaf Habib
Keyword(s):  
Black Hole ◽  
Active Galactic Nuclei ◽  
High Frequency ◽  
Kerr Black Hole ◽  
Galactic Nuclei ◽  
Tidal Disruption ◽  
Periodic Oscillations ◽  
Spinning Particle ◽  
X Ray ◽  
Test Particles

AbstractThe study of the quasi-periodic oscillations (QPOs) of X-ray flux observed in the stellar-mass black hole (BH) binaries or quasars can provide a powerful tool for testing the phenomena occurring in strong gravity regime. We thus fit the data of QPOs observed in the well known microquasars as well as active galactic nuclei (AGNs) in the framework of the model of geodesic oscillations of Keplerian disks modified for the epicyclic oscillations of spinning test particles orbiting Kerr BHs. We show that the modified geodesic models of QPOs can explain the observational fixed data from the microquasars and AGNs but not for all sources. We perform a successful fitting of the high frequency QPOs models of epicyclic resonance and its variants, relativistic precession and its variants, tidal disruption, as well as warped disc models, and discuss the corresponding constraints of parameters of the model, which are the spin of the test particle, mass and rotation of the BH.

scholarly journals To TDE or not to TDE: the luminous transient ASASSN-18jd with TDE-like and AGN-like qualities

2020 ◽  
Vol 494 (2) ◽  
pp. 2538-2560 ◽  
Author(s):  
J M M Neustadt ◽  
T W-S Holoien ◽  
C S Kochanek ◽  
K Auchettl ◽  
J S Brown ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Spectral Energy Distribution ◽  
Galactic Nuclei ◽  
Spectral Energy ◽  
Tidal Disruption ◽  
Optical Telescope ◽  
X Ray ◽  
Radiated Energy ◽  
The Galaxy ◽  
Order Of Magnitude

ABSTRACT We present the discovery of ASASSN-18jd (AT 2018bcb), a luminous optical/ultraviolet(UV)/X-ray transient located in the nucleus of the galaxy 2MASX J22434289–1659083 at z = 0.1192. Over the year after discovery, Swift UltraViolet and Optical Telescope (UVOT) photometry shows the UV spectral energy distribution of the transient to be well modelled by a slowly shrinking blackbody with temperature $T \sim 2.5 \times 10^{4} \, {\rm K}$, a maximum observed luminosity of $L_{\rm max} = 4.5^{+0.6}_{-0.3}\times 10^{44} \, {\rm erg \,s}^{-1}$, and a radiated energy of $E = 9.6^{+1.1}_{-0.6} \times 10^{51} \, {\rm erg}$. X-ray data from Swift X-Ray Telescope (XRT) and XMM–Newton show a transient, variable X-ray flux with blackbody and power-law components that fade by nearly an order of magnitude over the following year. Optical spectra show strong, roughly constant broad Balmer emission and transient features attributable to He ii, N iii–v, O iii, and coronal Fe. While ASASSN-18jd shares similarities with tidal disruption events (TDEs), it is also similar to the newly discovered nuclear transients seen in quiescent galaxies and faint active galactic nuclei (AGNs).

scholarly journals Aligning nuclear cluster orbits with an active galactic nucleus accretion disc

2020 ◽  
Vol 499 (2) ◽  
pp. 2608-2616 ◽  
Author(s):  
Gaia Fabj ◽  
Syeda S Nasim ◽  
Freddy Caban ◽  
K E Saavik Ford ◽  
Barry McKernan ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Gamma Ray ◽  
Galactic Nuclei ◽  
Tidal Disruption ◽  
Stellar Objects ◽  
Binary Black Hole ◽  
Disc Model ◽  
Inclination Angles ◽  
Nuclear Cluster ◽  
Repeated Passage

ABSTRACT Active galactic nuclei (AGN) are powered by the accretion of discs of gas on to supermassive black holes (SMBHs). Stars and stellar remnants orbiting the SMBH in the nuclear star cluster (NSC) will interact with the AGN disc. Orbiters plunging through the disc experience a drag force and, through repeated passage, can have their orbits captured by the disc. A population of embedded objects in AGN discs may be a significant source of binary black hole mergers, supernovae, tidal disruption events, and embedded gamma-ray bursts. For two representative AGN disc models, we use geometric drag and Bondi–Hoyle–Littleton drag to determine the time to capture for stars and stellar remnants. We assume a range of initial inclination angles and semimajor axes for circular Keplerian prograde orbiters. Capture time strongly depends on the density and aspect ratio of the chosen disc model, the relative velocity of the stellar object with respect to the disc, and the AGN lifetime. We expect that for an AGN disc density $\rho \gtrsim 10^{-11}{\rm g\, cm^{-3}}$ and disc lifetime ≥1 Myr, there is a significant population of embedded stellar objects, which can fuel mergers detectable in gravitational waves with LIGO-Virgo and LISA.

scholarly journals SDSS J0159 as an outlier in the MBH–σ space: further clues to support a central tidal disruption event?

2019 ◽  
Vol 490 (1) ◽  
pp. L81-L85 ◽  
Author(s):  
Xue-Guang Zhang ◽  
Min Bao ◽  
QiRong Yuan
Keyword(s):  
Active Galactic Nuclei ◽  
Line Emission ◽  
Galactic Nuclei ◽  
Host Galaxy ◽  
Broad Line ◽  
Tidal Disruption ◽  
Stellar Velocity ◽  
Interesting Object ◽  
Absorption Features ◽  
Disruption Event

ABSTRACT In this Letter, properties of black hole (BH) mass are well checked for the interesting object SDSS J0159, a changing-look active galactic nuclei and also a host galaxy of a tidal disruption event (TDE). Through spectral absorption features, the stellar velocity dispersion of SDSS J0159 can be well measured as $\sigma \sim 81~{\rm km\, s}^{-1}$, leading to SDSS J0159 being an apparent outlier in the MBH–σ space, because of the BH mass estimated through the MBH–σ relation about two magnitudes lower than the reported virial BH mass of about 108 M⊙. After considerations of contributions of stellar debris from the central TDE to broad line emission clouds, the overestimated virial BH mass could be well explained in SDSS J0159. Therefore, overestimated virial BH masses through broad-line properties in the MBH–σ space could be treated as interesting clues to support central TDEs.

scholarly journals A Sample of Massive Black Holes in Dwarf Galaxies Detected via [Fe x] Coronal Line Emission: Active Galactic Nuclei and/or Tidal Disruption Events

2021 ◽  
Vol 922 (2) ◽  
pp. 155
Author(s):  
Mallory Molina ◽  
Amy E. Reines ◽  
Colin J. Latimer ◽  
Vivienne Baldassare ◽  
Sheyda Salehirad
Keyword(s):  
Active Galactic Nuclei ◽  
Dwarf Galaxies ◽  
Line Emission ◽  
Galactic Nuclei ◽  
High Mass ◽  
Coronal Line ◽  
Tidal Disruption ◽  
Massive Black Hole ◽  
Coronal Line Emission ◽  
Stellar Sources

Abstract The massive black hole (BH) population in dwarf galaxies (M BH ≲ 105 M ⊙) can provide strong constraints on the origin of BH seeds. However, traditional optical searches for active galactic nuclei (AGNs) only reliably detect high-accretion, relatively high-mass BHs in dwarf galaxies with low amounts of star formation, leaving a large portion of the overall BH population in dwarf galaxies relatively unexplored. Here, we present a sample of 81 dwarf galaxies (M ⋆ ≤ 3 × 109 M ⊙) with detectable [Fe x]λ6374 coronal line emission indicative of accretion onto massive BHs, only two of which were previously identified as optical AGNs. We analyze optical spectroscopy from the Sloan Digital Sky Survey and find [Fe x]λ6374 luminosities in the range L [Fe x] ≈ 1036–1039 erg s−1, with a median value of 1.6 × 1038 erg s−1. The [Fe x] λ6374 luminosities are generally much too high to be produced by stellar sources, including luminous Type IIn supernovae (SNe). Moreover, based on known SNe rates, we expect at most eight Type IIn SNe in our sample. That said, the [Fe x]λ6374 luminosities are consistent with accretion onto massive BHs from AGNs or tidal disruption events (TDEs). We find additional indicators of BH accretion in some cases using other emission line diagnostics, optical variability, and X-ray and radio emission (or some combination of these). However, many of the galaxies in our sample only have evidence for a massive BH based on their [Fe x]λ6374 luminosities. This work highlights the power of coronal line emission to find BHs in dwarf galaxies missed by other selection techniques and to probe the BH population in bluer, lower-mass dwarf galaxies.

scholarly journals Light Curves of Tidal Disruption Events in Active Galactic Nuclei

2020 ◽  
Vol 903 (1) ◽  
pp. 17 ◽  
Author(s):  
Chi-Ho Chan ◽  
Tsvi Piran ◽  
Julian H. Krolik
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Light Curves ◽  
Tidal Disruption

scholarly journals A Comparison of the X-Ray Emission from Tidal Disruption Events with those of Active Galactic Nuclei

2018 ◽  
Vol 852 (1) ◽  
pp. 37 ◽  
Author(s):  
Katie Auchettl ◽  
Enrico Ramirez-Ruiz ◽  
James Guillochon
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Tidal Disruption ◽  
X Ray
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