scholarly journals The unusual late-time evolution of the tidal disruption event ASASSN-15oi

2018 ◽  
Vol 480 (4) ◽  
pp. 5689-5703 ◽  
Author(s):  
T W-S Holoien ◽  
J S Brown ◽  
K Auchettl ◽  
C S Kochanek ◽  
J L Prieto ◽  
...  
Keyword(s):  
Time Evolution ◽  
Late Time ◽  
Tidal Disruption ◽  
Disruption Event

scholarly journals Radio Monitoring of the Tidal Disruption Event Swift J164449.3+573451. III. Late-time Jet Energetics and a Deviation from Equipartition

2018 ◽  
Vol 854 (2) ◽  
pp. 86 ◽  
Author(s):  
T. Eftekhari ◽  
E. Berger ◽  
B. A. Zauderer ◽  
R. Margutti ◽  
K. D. Alexander
Keyword(s):  
Late Time ◽  
Tidal Disruption ◽  
Radio Monitoring ◽  
Disruption Event

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

2019 ◽  
Vol 488 (2) ◽  
pp. 1878-1893 ◽  
Author(s):  
M Nicholl ◽  
P K Blanchard ◽  
E Berger ◽  
S Gomez ◽  
R Margutti ◽  
...  
Keyword(s):  
Host Galaxy ◽  
Mass Star ◽  
Late Time ◽  
Solar Mass ◽  
Tidal Disruption ◽  
Relativistic Jet ◽  
Proposed Model ◽  
Complete Disruption ◽  
Disruption Event ◽  
Rule Out

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.

scholarly journals Rapid late-time X-ray brightening of the tidal disruption event OGLE16aaa

2020 ◽  
Vol 639 ◽  
pp. A100 ◽  
Author(s):  
Jari J. E. Kajava ◽  
Margherita Giustini ◽  
Richard D. Saxton ◽  
Giovanni Miniutti
Keyword(s):  
Black Hole ◽  
Host Galaxy ◽  
Late Time ◽  
Tidal Disruption ◽  
Massive Black Hole ◽  
X Ray ◽  
Tidal Forces ◽  
Upper Limits ◽  
Optical Light Curve ◽  
Disruption Event

Stars that pass too close to a super-massive black hole may be disrupted by strong tidal forces. OGLE16aaa is one such tidal disruption event (TDE) which rapidly brightened and peaked in the optical/UV bands in early 2016 and subsequently decayed over the rest of the year. OGLE16aaa was detected in an XMM-Newton X-ray observation on June 9, 2016 with a flux slightly below the Swift/XRT upper limits obtained during the optical light curve peak. Between June 16–21, 2016, Swift/XRT also detected OGLE16aaa and based on the stacked spectrum, we could infer that the X-ray luminosity had jumped up by more than a factor of ten in just one week. No brightening signal was seen in the simultaneous optical/UV data to cause the X-ray luminosity to exceed the optical/UV one. A further XMM-Newton observation on November 30, 2016 showed that almost a year after the optical/UV peak, the X-ray emission was still at an elevated level, while the optical/UV flux decay had already leveled off to values comparable to those of the host galaxy. In all X-ray observations, the spectra were nicely modeled with a 50–70 eV thermal component with no intrinsic absorption, with a weak X-ray tail seen only in the November 30 XMM-Newton observation. The late-time X-ray behavior of OGLE16aaa strongly resembles the tidal disruption events ASASSN-15oi and AT2019azh. We were able to pinpoint the time delay between the initial optical TDE onset and the X-ray brightening to 182 ± 5 days, which may possibly represent the timescale between the initial circularization of the disrupted star around the super-massive black hole and the subsequent delayed accretion. Alternatively, the delayed X-ray brightening could be related to a rapid clearing of a thick envelope that covers the central X-ray engine during the first six months.

scholarly journals Late time X-ray, IR and radio observations of the tidal disruption event galaxy NGC 5905

2015 ◽  
Vol 357 (1) ◽  
Author(s):  
H. Raichur ◽  
M. Das ◽  
A. Alonso Herrero ◽  
P. Shastri ◽  
N. G. Kantharia
Keyword(s):  
Late Time ◽  
Radio Observations ◽  
Tidal Disruption ◽  
X Ray ◽  
Disruption Event

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

2019 ◽  
Vol 489 (1) ◽  
pp. 1463-1480 ◽  
Author(s):  
F Onori ◽  
G Cannizzaro ◽  
P G Jonker ◽  
M Fraser ◽  
Z Kostrzewa-Rutkowska ◽  
...  
Keyword(s):  
Exponential Decay ◽  
Emission Lines ◽  
Host Galaxy ◽  
Late Time ◽  
Tidal Disruption ◽  
Optical Telescope ◽  
Bolometric Luminosity ◽  
Luminosity Evolution ◽  
Disruption Event

ABSTRACT 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 d 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 t0 = 17.6 ± 0.2 d. The early-time spectra of the transient are dominated by broad He ii λ4686, H $\beta$, H $\alpha$, and N iii λ4100 emission lines. The latter is known to be produced together with the N iii λ4640 in the Bowen fluorescence mechanism. Due 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 active galactic nucleus 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 at 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.

scholarly journals Possible X-Ray Quasi-periodic Eruptions in a Tidal Disruption Event Candidate

2021 ◽  
Vol 921 (2) ◽  
pp. L40
Author(s):  
Joheen Chakraborty ◽  
Erin Kara ◽  
Megan Masterson ◽  
Margherita Giustini ◽  
Giovanni Miniutti ◽  
...  
Keyword(s):  
Tidal Disruption ◽  
X Ray ◽  
Disruption Event

scholarly journals Long-term radio and X-ray evolution of the tidal disruption event ASASSN-14li

2018 ◽  
Vol 475 (3) ◽  
pp. 4011-4019 ◽  
Author(s):  
J S Bright ◽  
R P Fender ◽  
S E Motta ◽  
K Mooley ◽  
Y C Perrott ◽  
...  
Keyword(s):  
Tidal Disruption ◽  
X Ray ◽  
Disruption Event

scholarly journals Relativistic accretion disc in tidal disruption events

2020 ◽  
Vol 496 (2) ◽  
pp. 1784-1802
Author(s):  
T Mageshwaran ◽  
Sudip Bhattacharyya
Keyword(s):  
Surface Density ◽  
Accretion Disc ◽  
Time Parameter ◽  
Light Curves ◽  
Initial Time ◽  
Late Time ◽  
Tidal Disruption ◽  
Bolometric Luminosity ◽  
Spectral Bands ◽  
Accretion Model

ABSTRACT We construct a time-dependent relativistic accretion model for tidal disruption events (TDEs) with an α-viscosity and the pressure dominated by gas pressure. We also include the mass fallback rate $\dot{M}_\mathrm{ f}$ for both full and partial disruption TDEs, and assume that the infalling debris forms a seed disc in time tc, which evolves due to the mass addition from the infalling debris and the mass-loss via accretion on to the black hole. Besides, we derive an explicit form for the disc height that depends on the angular momentum parameter in the disc. We show that the surface density of the disc increases at an initial time due to mass addition, and then decreases as the mass fallback rate decreases, which results in a decrease in the disc mass Md with a late-time evolution of Md ∝ t−1.05 and t−1.38 for full and partial disruption TDEs, respectively, where t is the time parameter. The bolometric luminosity L shows a rise and decline that follows a power law at late times given by L ∝ t−1.8 and t−2.3 for full and partial disruption TDEs, respectively. Our obtained luminosity declines faster than the luminosity inferred using $L \propto \dot{M}_\mathrm{ f}$. We also compute the light curves in various spectral bands.

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