scholarly journals Differentiating disc and black hole-driven jets with EHT images of variability in M87

2020 ◽  
Vol 493 (4) ◽  
pp. 5606-5616 ◽  
Author(s):  
Britton Jeter ◽  
Avery E Broderick ◽  
Roman Gold
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Light Curve ◽  
Maximum Intensity ◽  
Light Curves ◽  
Long Baseline ◽  
Vlbi Observations ◽  
Jet Variability ◽  
Model Variability ◽  
Intensity Decay

ABSTRACT Millimetre-wavelength very long baseline interferometric (mm-VLBI) observations of M87 by the Event Horizon Telescope (EHT) should provide a unique opportunity to observe and characterize the origins of jet variability already seen at longer wavelengths. Synchrotron spot models have been used to model variability near black holes; this work extends these by allowing spots to shear and deform in the jet velocity field. Depending on the position of the spot, shearing forces can significantly alter the structure of the spot, producing distinct signals in reconstructed images and light curves. The maximum intensity of the shearing spot can vary by as much as a factor of 5 depending on the spot azimuthal launch position, but the intensity decay time depends most significantly on the spot radial launch position. Spots launched by a black hole-driven jet exhibit distinct arc structures in reconstructed images, and exhibit brighter and shorter lived enhancements of the light curve. Spots launched by a wind-driven jet have exhibit much simpler structures in the image, and longer lived light-curve enhancements than spots launched by a black hole-driven jet.

scholarly journals Simulations of M87 and Sgr A* imaging with the Millimetron Space Observatory on near-Earth orbits

2020 ◽  
Vol 500 (4) ◽  
pp. 4866-4877
Author(s):  
A S Andrianov ◽  
A M Baryshev ◽  
H Falcke ◽  
I A Girin ◽  
T de Graauw ◽  
...  
Keyword(s):  
Black Hole ◽  
Space Mission ◽  
Dynamic Imaging ◽  
Image Resolution ◽  
Fast Time ◽  
Supermassive Black Hole ◽  
Long Baseline ◽  
Vlbi Observations ◽  
Sgr A ◽  
Earth Orbits

ABSTRACT High-resolution imaging of supermassive black hole shadows is a direct way to verify the theory of general relativity under extreme gravity conditions. Very Long Baseline Interferometry (VLBI) observations at millimetre/submillimetre wavelengths can provide such angular resolution for the supermassive black holes located in Sgr A* and M87. Recent VLBI observations of M87 with the Event Horizon Telescope (EHT) have shown such capabilities. The maximum obtainable spatial resolution of the EHT is limited by the Earth's diameter and atmospheric phase variations. In order to improve the image resolution, longer baselines are required. The Radioastron space mission successfully demonstrated the capabilities of space–Earth VLBI with baselines much longer than the Earth's diameter. Millimetron is the next space mission of the Russian Space Agency and will operate at millimetre wavelengths. The nominal orbit of the observatory will be located around the Lagrangian L2 point of the Sun–Earth system. In order to optimize the VLBI mode, we consider a possible second stage of the mission that could use a near-Earth high elliptical orbit (HEO). In this paper, a set of near-Earth orbits is used for synthetic space–Earth VLBI observations of Sgr A* and M87 in a joint Millimetron and EHT configuration. General relativistic magnetohydrodynamic models for the supermassive black hole environments of Sgr A* and M87 are used for static and dynamic imaging simulations at 230 GHz. A comparison preformed between ground and space–Earth baselines demonstrates that joint observations with Millimetron and EHT significantly improve the image resolution and allow the EHT + Millimetron to obtain snapshot images of Sgr A*, probing the dynamics at fast time-scales.

THE PERIODICITY ANALYSIS OF THE LIGHT CURVE OF PKS 0735+178 AND IMPLICATIONS FOR ITS CENTRAL STRUCTURE

2004 ◽  
Vol 13 (04) ◽  
pp. 771-782 ◽  
Author(s):  
S. X. DING ◽  
G. Z. XIE ◽  
E. W. LIANG ◽  
S. B. ZHOU ◽  
L. MA
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Light Curve ◽  
Observation Data ◽  
Binary Black Hole ◽  
Periodicity Analysis ◽  
Power Spectrum Method ◽  
Hole Model ◽  
The Masses ◽  
Good Agreement

The observation data in the B band for BL Lacerate object PKS 0735+178 during 1970–1998 from twenty two publications have been compiled into a light curve. The light curve shows that PKS 0735+178 is very active and exhibits very complicated non-sinusoidal variations. Using both Jurkevich's method and Power spectrum method to analyze these data we have found two periods of 5.26±0.98 years and 1.24±0.05 years for the outbursts in PKS 0735+178. It is of interest to note that the results of the two methods are the same (almost). In addition, these values are in good agreement with the results found by Smith et al.47 and Webb et al.61 We also apply the binary black hole model to explain the central structure of this object and obtain the masses of the primary and secondary black holes are 1.7×109M⊙ and 2.88×107M⊙ respectively. It should be monitored in future to obtain more data for further analysis to test the hypothesis.

scholarly journals Event horizon scale emission models for Sagittarius A*

2013 ◽  
Vol 9 (S303) ◽  
pp. 298-302
Author(s):  
J. Dexter
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Event Horizon ◽  
Near Infrared ◽  
Sagittarius A ◽  
Long Baseline ◽  
Black Hole Accretion ◽  
Emission Models ◽  
Infrared Interferometry ◽  
Sgr A

AbstractVery long baseline interferometry observations at millimeter wavelengths have detected source structure in Sgr A* on event horizon scales. Near-infrared interferometry will achieve similar resolution in the next few years. These experiments provide an unprecedented opportunity to explore strong gravity around black holes, but interpreting the data requires physical modeling. I discuss the calculation of images, spectra, and light curves from relativistic MHD simulations of black hole accretion. The models provide an excellent description of current observations, and predict that we may be on the verge of detecting a black hole shadow, which would constitute the first direct evidence for the existence of black holes.

scholarly journals Black holes in the quantum universe

2019 ◽  
Vol 377 (2161) ◽  
pp. 20190029 ◽  
Author(s):  
Steven B. Giddings
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Quantum Mechanics ◽  
Gravitational Wave ◽  
New Physics ◽  
Standard Description ◽  
Long Baseline ◽  
Quantum Universe

A succinct summary is given of the problem of reconciling observation of black hole-like objects with quantum mechanics. If quantum black holes behave like subsystems, and also decay, their information must be transferred to their environments. Interactions that accomplish this with ‘minimal’ departure from a standard description are parametrized. Possible sensitivity of gravitational wave or very long baseline interferometric observations to these interactions is briefly outlined. This article is part of a discussion meeting issue ‘Topological avatars of new physics’.

scholarly journals ASASSN-15lh: a TDE about a maximally rotating 109 M⊙ black hole

2020 ◽  
Vol 497 (1) ◽  
pp. L13-L18 ◽  
Author(s):  
Andrew Mummery ◽  
Steven A Balbus
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Light Curves ◽  
The Novel ◽  
Black Hole Mass ◽  
Tidal Disruption ◽  
Scaling Relationships ◽  
Best Fitting ◽  
Infrared Frequencies ◽  
Disruption Event

ABSTRACT We model the light curves of the novel and extremely luminous transient ASASSN-15lh at nine different frequencies, from infrared to ultraviolet photon energies, as an evolving relativistic disc produced in the aftermath of a tidal disruption event (TDE). Good fits to all nine light curves are simultaneously obtained when Macc ≃ 0.07 M⊙ is accreted on to a black hole of mass M ≃ 109 M⊙ and near-maximal rotation a/rg = 0.99. The best-fitting black hole mass is consistent with a number of existing estimates from galactic scaling relationships. If confirmed, our results represent the detection of one of the most massive rapidly spinning black holes to date, and are strong evidence for a TDE origin for ASASSN-15lh. This would be the first TDE to be observed in the disc-dominated state at optical and infrared frequencies.

scholarly journals Multiple black hole system in 4C31.61 (2201+315)

2020 ◽  
Vol 634 ◽  
pp. A101
Author(s):  
J. Roland ◽  
C. Gattano ◽  
S. B. Lambert ◽  
F. Taris
Keyword(s):  
Time Series ◽  
Black Holes ◽  
Black Hole ◽  
Very Long Baseline Interferometry ◽  
Radio Sources ◽  
Mass Ratio ◽  
The Third ◽  
Long Baseline ◽  
Binary Black Hole ◽  
Different Origins

Modeling trajectories of radio components ejected by the nucleus of 4C31.61 (2201+315) and observed by very long baseline interferometry (VLBI) in the frame of the MOJAVE survey suggests that they are ejected from three different origins that possibly host three different supermassive black holes. These origins correspond to three stationary components, one of which one is the VLBI core. Most of the mass of the nucleus is associated with a supermassive binary black hole system whose separation is ≈0.3 milliarc second, that is, a distance of ≈1.3 parsec and the mass ratio is ≈2. In contrast, the mass ratio with respect to the third black hole is ≈1/100. The three origins lie within 0.6 milliarc second, or a distance of ≈2.6 parsec. Based in this structure of the nucleus, we explain the variations observed in the astrometric coordinate time series obtained from VLBI geodetic surveys. This study shows that it is possible to exploit large MOJAVE-like VLBI databases to propose more insights into the structure of the extragalactic radio sources that are targeted by VLBI in geodetic and astrometry programs.

scholarly journals Study of Periodic Signals from Blazars

Proceedings ◽  
2019 ◽  
Vol 17 (1) ◽  
pp. 15
Author(s):  
Gopal Bhatta
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Gamma Ray ◽  
Supermassive Black Holes ◽  
Light Curves ◽  
Supermassive Black Hole ◽  
Transient Nature ◽  
Time Series Analyses ◽  
Periodic Signals

The search for periodic signals from blazars has become an actively pursued field of research in recent years. This is because periodic signals bring us information about the processes occurring near the innermost regions of blazars, which are mostly inaccessible to our direct view. Such signals provide insights into some of the extreme conditions that take place in the vicinity of supermassive black holes that lead to the launch of the relativistic jets. In addition, studies of characteristic timescales in blazar light curves shed light on some of the challenging issues in blazar physics that include disk-jet connection, strong gravity near fast-rotating supermassive black holes and release of gravitational waves from binary supermassive black hole systems. However, a number of issues associated with the search for quasi-periodic oscillations (QPOs) in blazars e.g., red-noise dominance, modest significance of the detection, periodic modulation lasting for only a couple of cycles and their transient nature, make it difficult to estimate the true significance of the detection. Consequently, it also becomes difficult to make meaningful inferences about the nature of the on-going processes. In this proceedings, results of study focused on searching for QPOs in a number of blazar multi-frequency light curves are summarized. The time series analyses of long term observations of the blazars revealed the presence of year-timescale QPOs in the sources including OJ 287 (optical), Mrk 501 (gamma-ray), J1043+2408 (radio) and PKS 0219-164 (radio). A likely explanations, we discuss a number of scenarios including binary supermassive black hole systems, lense-thirring precession, and jet precession.

scholarly journals Emission peaks in the light curve of core collapse supernovae by late jets

2020 ◽  
Vol 492 (2) ◽  
pp. 3013-3020 ◽  
Author(s):  
Noa Kaplan ◽  
Noam Soker
Keyword(s):  
Black Hole ◽  
Kinetic Energy ◽  
Light Curve ◽  
Emission Peak ◽  
Light Curves ◽  
Core Collapse ◽  
Spherically Symmetric ◽  
Emission Power ◽  
Strong Emission ◽  
Central Object

ABSTRACT We build a toy model where the central object, i.e. a newly born neutron star or a black hole, launches jets at late times and show that these jets might account for peaks in the light curve of some peculiar (i.e. having unusual light curves) core collapse supernovae (CCSNe) when the jets interact with the CCSN ejecta. We assume that the central object accretes fallback material and launches two short-lived opposite jets weeks to months after the explosion. We model each jet-ejecta interaction as a spherically symmetric ‘mini-explosion’ that takes place inside the ejecta. We assume that each ‘mini-explosion’ adds emission that is symmetric in time around the late peak, and with a rise in emission power that has the same slope as that of the main CCSN light curve. In total, we use 12 parameters in the toy model. In our toy model, late jets form stronger emission peaks than early jets. Late jets with a kinetic energy of only about one per cent of the kinetic energy of the CCSN itself might form strong emission peaks. We apply our toy model to the brightest peak of the enigmatic CCSN iPTF14hls that has several extra peaks in its light curve. We can fit this emission peak with our toy model when we take the kinetic energy of the jets to be about 1–2 per cent of the CCSN energy, and the shocked ejecta mass to be about 3 per cent of the ejecta mass.

The Eclipsing Binary WX Eridani

1979 ◽  
Vol 46 ◽  
pp. 385
Author(s):  
M.B.K. Sarma ◽  
K.D. Abhankar
Keyword(s):  
Light Curve ◽  
Spectral Type ◽  
Orbital Period ◽  
Primary Component ◽  
Light Curves ◽  
Absorption Feature ◽  
Primary Star ◽  
Eclipsing Binary ◽  
The Times ◽  
Phase Angles

AbstractThe Algol-type eclipsing binary WX Eridani was observed on 21 nights on the 48-inch telescope of the Japal-Rangapur Observatory during 1973-75 in B and V colours. An improved period of P = 0.82327038 days was obtained from the analysis of the times of five primary minima. An absorption feature between phase angles 50-80, 100-130, 230-260 and 280-310 was present in the light curves. The analysis of the light curves indicated the eclipses to be grazing with primary to be transit and secondary, an occultation. Elements derived from the solution of the light curve using Russel-Merrill method are given. From comparison of the fractional radii with Roche lobes, it is concluded that none of the components have filled their respective lobes but the primary star seems to be evolving. The spectral type of the primary component was estimated to be F3 and is found to be pulsating with two periods equal to one-fifth and one-sixth of the orbital period.

scholarly journals An extensive photometric study of the Blazhko RR Lyrae star RZ Lyr*

2012 ◽  
Vol 423 (2) ◽  
pp. 993-1005 ◽  
Author(s):  
J. Jurcsik ◽  
Á. Sódor ◽  
G. Hajdu ◽  
B. Szeidl ◽  
Á. Dózsa ◽  
...  
Keyword(s):  
Light Curve ◽  
Light Curves ◽  
Stellar Structure ◽  
Time Base ◽  
Photometric Method ◽  
Physical Parameters ◽  
Component Solution ◽  
Rr Lyrae ◽  
Curve Variation ◽  
Type Variable

Abstract The analysis of recent, extended multicolour CCD and archive photoelectric, photographic and visual observations has revealed several important properties of RZ Lyr, an RRab-type variable exhibiting large-amplitude Blazhko modulation. On the time base of ∼110 yr, a strict anticorrelation between the pulsation- and modulation-period changes is established. The light curve of RZ Lyr shows a remarkable bump on the descending branch in the small-amplitude phase of the modulation, similarly to the light curves of bump Cepheids. We speculate that the stellar structure temporally suits a 4:1 resonance between the periods of the fundamental and one of the higher order radial modes in this modulation phase. The light-curve variation of RZ Lyr can be correctly fitted with a two-modulation-component solution; the 121-d period of the main modulation is nearly but not exactly four times longer than the period of the secondary modulation component. Using the inverse photometric method, the variations in the pulsation-averaged values of the physical parameters in different phases of both modulation components are determined.

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