scholarly journals Accretion-induced variability links young stellar objects, white dwarfs, and black holes

2015 ◽  
Vol 1 (9) ◽  
pp. e1500686 ◽  
Author(s):  
Simone Scaringi ◽  
Thomas J. Maccarone ◽  
Elmar Körding ◽  
Christian Knigge ◽  
Simon Vaughan ◽  
...  
Keyword(s):  
Black Holes ◽  
Active Galactic Nuclei ◽  
White Dwarfs ◽  
Galactic Nuclei ◽  
Stellar Mass ◽  
Supermassive Black Holes ◽  
Young Stellar Objects ◽  
Scaling Relation ◽  
Forming Process ◽  
Stellar Objects

The central engines of disc-accreting stellar-mass black holes appear to be scaled down versions of the supermassive black holes that power active galactic nuclei. However, if the physics of accretion is universal, it should also be possible to extend this scaling to other types of accreting systems, irrespective of accretor mass, size, or type. We examine new observations, obtained withKepler/K2and ULTRACAM, regarding accreting white dwarfs and young stellar objects. Every object in the sample displays the same linear correlation between the brightness of the source and its amplitude of variability (rms-flux relation) and obeys the same quantitative scaling relation as stellar-mass black holes and active galactic nuclei. We also show that the most important parameter in this scaling relation is the physical size of the accreting object. This establishes the universality of accretion physics from proto-stars still in the star-forming process to the supermassive black holes at the centers of galaxies.

scholarly journals Epicyclic Oscillations around Simpson–Visser Regular Black Holes and Wormholes

Universe ◽  
2021 ◽  
Vol 7 (8) ◽  
pp. 279
Author(s):  
Zdeněk Stuchlík ◽  
Jaroslav Vrba
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Active Galactic Nuclei ◽  
Observational Data ◽  
High Frequency ◽  
Galactic Nuclei ◽  
Supermassive Black Holes ◽  
Periodic Oscillations ◽  
High Length ◽  
Circular Geodesic

We study epicyclic oscillatory motion along circular geodesics of the Simpson–Visser meta-geometry describing in a unique way regular black-bounce black holes and reflection-symmetric wormholes by using a length parameter l. We give the frequencies of the orbital and epicyclic motion in a Keplerian disc with inner edge at the innermost circular geodesic located above the black hole outer horizon or on the our side of the wormhole. We use these frequencies in the epicyclic resonance version of the so-called geodesic models of high-frequency quasi-periodic oscillations (HF QPOs) observed in microquasars and around supermassive black holes in active galactic nuclei to test the ability of this meta-geometry to improve the fitting of HF QPOs observational data from the surrounding of supermassive black holes. We demonstrate that this is really possible for wormholes with sufficiently high length parameter l.

scholarly journals Supermassive black holes surrounded by dark matter modeled as anisotropic fluid: epicyclic oscillations and their fitting to observed QPOs

2021 ◽  
Vol 2021 (11) ◽  
pp. 059
Author(s):  
Z. Stuchlík ◽  
J. Vrba
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Dark Matter ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Supermassive Black Holes ◽  
Anisotropic Fluid ◽  
Physical Parameters ◽  
Black Hole Spacetimes ◽  
Test Particles

Abstract Recently introduced exact solution of the Einstein gravity coupled minimally to an anisotropic fluid representing dark matter can well represent supermassive black holes in galactic nuclei with realistic distribution of dark matter around the black hole, given by the Hernquist-like density distribution. For these fluid-hairy black hole spacetimes, properties of the gravitational radiation, quasinormal ringing, and optical phenomena were studied, giving interesting results. Here, using the range of physical parameters of these spacetimes allowing for their relevance in astrophysics, we study the epicyclic oscillatory motion of test particles in these spacetimes. The frequencies of the orbital and epicyclic motion are applied in the epicyclic resonance variant of the geodesic model of quasiperiodic oscillations (QPOs) observed in active galactic nuclei to demonstrate the possibility to solve the cases where the standard vacuum black hole spacetimes are not allowing for explanation of the observed data. We demonstrate that the geodesic model can explain the QPOs observed in most of the active galactic nuclei for the fluid-hairy black holes with reasonable halo parameters.

Dependence of the Spin of Supermassive Black Holes on the Eddington Factor for Accretion Disks in Active Galactic Nuclei

Astrophysics ◽  
2016 ◽  
Vol 59 (4) ◽  
pp. 439-448 ◽  
Author(s):  
M. Yu. Piotrovich ◽  
S. D. Buliga ◽  
Yu. N. Gnedin ◽  
A. G. Mikhailov ◽  
T. M. Natsvlishvili
Keyword(s):  
Black Holes ◽  
Active Galactic Nuclei ◽  
Accretion Disks ◽  
Galactic Nuclei ◽  
Supermassive Black Holes

scholarly journals Search for wormhole candidates in active galactic nuclei: radiation from colliding accreting flows

2020 ◽  
Vol 498 (3) ◽  
pp. 3684-3686
Author(s):  
M Yu Piotrovich ◽  
S V Krasnikov ◽  
S D Buliga ◽  
T M Natsvlishvili
Keyword(s):  
Black Holes ◽  
Gamma Radiation ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Supermassive Black Holes ◽  
Accretion Discs

ABSTRACT The underlying hypothesis of this work is that the active galactic nuclei (AGNs) are wormhole mouths rather than supermassive black holes. Under some – quite general – assumptions such wormholes may emit gamma radiation as a result of a collision of accreting flows inside the wormholes. This radiation has a distinctive spectrum much different from those of jets or accretion discs of AGNs. An observation of such radiation would serve as evidence of the existence of wormholes.

Determination of supermassive black hole spins in active galactic nuclei

2020 ◽  
Vol 35 (02n03) ◽  
pp. 2040054
Author(s):  
M. Yu. Piotrovich ◽  
V. L. Afanasiev ◽  
S. D. Buliga ◽  
T. M. Natsvlishvili
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Active Galactic Nuclei ◽  
Accretion Disk ◽  
Galactic Nuclei ◽  
Supermassive Black Holes ◽  
Disk Model ◽  
Supermassive Black Hole

Based on spectropolarimetry for a number of active galactic nuclei in Seyfert 1 type galaxies observed with the 6-m BTA telescope, we have estimated the spins of the supermassive black holes at the centers of these galaxies. We have determined the spins based on the standard Shakura-Sunyaev accretion disk model. More than 70% of the investigated active galactic nuclei are shown to have Kerr supermassive black holes with a dimensionless spin greater than 0.9.

scholarly journals Water fountains: bipolar fast stellar jets traced by water vapor maser emission

2012 ◽  
Vol 8 (S290) ◽  
pp. 227-228
Author(s):  
Hiroshi Imai
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Asymptotic Giant Branch ◽  
Young Stellar Objects ◽  
Agb Stars ◽  
Stellar Objects ◽  
Stellar Jets ◽  
The Masses ◽  
Host Stars ◽  
Maser Sources

AbstractHighly collimated, bipolar fast jets are found in asymptotic giant branch (AGB) and post-AGB stars as well as in active galactic nuclei and young stellar objects. It is still unclear how to launch such jets from dying stars that were originally spherically symmetric. Exploration of the stellar jet evolution is also expected to probe its role in shaping a planetary nebula. Interestingly, some of stellar H2O maser sources — water fountains — exhibit stellar jets with spatially and kinematically high collimation in the earliest phase (<1000 years) of the jet evolution. Such water fountains have been identified in 14 sources to date. We have recently conducted interferometric (VLBA, EVN, VERA, VLA) maser and the single-dish (ASTE) CO J = 3 → 2 line observations of the water fountains. They have revealed a typical dynamical age (< 100 yr) and the detailed kinematical structures of the water fountains, possibility of the coexistence of “equatorial flows”, and their locations and kinematics in the Milky Way. Based on these results, the masses and evolutionary statuses of the host stars are also estimated.

scholarly journals MAGNETIC FIELD EFFECTS NEAR THE LAUNCHING REGION OF ASTROPHYSICAL JETS

2010 ◽  
Vol 19 (06) ◽  
pp. 729-739 ◽  
Author(s):  
E. M. DE GOUVEIA DAL PINO ◽  
G. KOWAL ◽  
L. H. S. KADOWAKI ◽  
P. PIOVEZAN ◽  
A. LAZARIAN
Keyword(s):  
Magnetic Field ◽  
Active Galactic Nuclei ◽  
Magnetic Energy ◽  
Galactic Nuclei ◽  
Young Stellar Objects ◽  
Magnetic Field Effects ◽  
Astrophysical Jets ◽  
Stellar Objects ◽  
Fundamental Properties

One of the fundamental properties of astrophysical magnetic fields is their ability to change topology through reconnection and in doing so, to release magnetic energy, sometimes violently. In this work, we review recent results on the role of magnetic reconnection and associated heating and particle acceleration in jet/accretion disk systems, namely young stellar objects (YSOs), microquasars, and active galactic nuclei (AGNs).

Sign in / Sign up

Export Citation Format

Share Document