scholarly journals Relativistic Jets from AGN Viewed at Highest Angular Resolution

Galaxies ◽  
2019 ◽  
Vol 8 (1) ◽  
pp. 1 ◽  
Author(s):  
Kazuhiro Hada
Keyword(s):  
Black Hole ◽  
Spatial Scales ◽  
High Energy ◽  
Rapid Expansion ◽  
Relativistic Jets ◽  
Energy Bands ◽  
Theoretical Understanding ◽  
Broadband Emission ◽  
Long Baseline ◽  
Magnetohydrodynamic Simulations

Accreting supermassive black holes in active galactic nuclei (AGN) produce powerful relativistic jets that shine from radio to GeV/TeV γ-rays. Over the past decade, AGN jets have extensively been studied in various energy bands and our knowledge about the broadband emission and rapid flares are now significantly updated. Meanwhile, the progress of magnetohydrodynamic simulations with a rotating black hole have greatly improved our theoretical understanding of powerful jet production. Nevertheless, it is still challenging to observationally resolve such flaring sites or jet formation regions since the relevant spatial scales are tiny. Observations with very long baseline interferometry (VLBI) are currently the only way to directly access such compact scales. Here we overview some recent progress of VLBI studies of AGN jets. As represented by the successful black hole shadow imaging with the Event Horizon Telescope, the recent rapid expansion of VLBI capability is remarkable. The last decade has also seen a variety of advances thanks to the advent of RadioAstron, GMVA, new VLBI facilities in East Asia as well as to the continued upgrade of VLBA. These instruments have resolved the innermost regions of relativistic jets for a number of objects covering a variety of jetted AGN classes (radio galaxies, blazars, and narrow-line Seyfert 1 galaxies), and the accumulated results start to establish some concrete (and likely universal) picture on the collimation, acceleration, recollimation shocks, magnetic field topology, and the connection to high-energy flares in the innermost part of AGN jets.

scholarly journals Broadband study of blazar 1ES 1959+650 during flaring state in 2016

2018 ◽  
Vol 611 ◽  
pp. A44 ◽  
Author(s):  
S. R. Patel ◽  
A. Shukla ◽  
V. R. Chitnis ◽  
D. Dorner ◽  
K. Mannheim ◽  
...  
Keyword(s):  
High Energy ◽  
Spectral Energy ◽  
Quiescent State ◽  
Energy Bands ◽  
Energy Distributions ◽  
X Ray ◽  
Broadband Emission ◽  
June July ◽  
Power Law Index ◽  
Observation Period

Aims. The nearby TeV blazar 1ES 1959+650 (z = 0.047) was reported to be in flaring state during June–July 2016 by Fermi-LAT, FACT, MAGIC and VERITAS collaborations. We studied the spectral energy distributions (SEDs) in different states of the flare during MJD 57530–57589 using simultaneous multiwaveband data with the aim of understanding the possible broadband emission scenario during the flare. Methods. The UV-optical and X-ray data from UVOT and XRT respectively on board Swift and high energy γ-ray data from Fermi-LAT were used to generate multiwaveband lightcurves as well as to obtain high flux states and quiescent state SEDs. The correlation and lag between different energy bands was quantified using discrete correlation function. The synchrotron self-Compton (SSC) model was used to reproduce the observed SEDs during flaring and quiescent states of the source. Results. A good correlation is seen between X-ray and high energy γ-ray fluxes. The spectral hardening with increase in the flux is seen in X-ray band. The power law index vs. flux plot in γ-ray band indicates the different emission regions for 0.1–3 GeV and 3–300 GeV energy photons. Two zone SSC model satisfactorily fits the observed broadband SEDs. The inner zone is mainly responsible for producing synchrotron peak and high energy γ-ray part of the SED in all states. The second zone is mainly required to produce less variable optical-UV and low energy γ-ray emission. Conclusions. Conventional single zone SSC model does not satisfactorily explain broadband emission during observation period considered. There is an indication of two emission zones in the jet which are responsible for producing broadband emission from optical to high energy γ-rays.

scholarly journals A self-lensing supermassive binary black hole at radio frequencies: the story of Spikey continues

2020 ◽  
Vol 496 (3) ◽  
pp. 3336-3347
Author(s):  
Emma Kun ◽  
Sándor Frey ◽  
Krisztina É Gabányi
Keyword(s):  
Black Hole ◽  
Flux Density ◽  
Structural Model ◽  
High Energy ◽  
Secular Change ◽  
Long Baseline ◽  
Morphological Model ◽  
Optical Light Curve ◽  
5 Ghz ◽  
Jet Structure

ABSTRACT The quasar J1918+4937 was recently suggested to harbour a milliparsec-separation binary supermassive black hole (SMBH), based upon modelling the narrow spike in its high-cadence Kepler optical light curve. Known binary SMBHs are extremely rare, and the tight constraints on the physical and geometric parameters of this object are unique. The high-resolution radio images of J1918+4937 obtained with very long baseline interferometry (VLBI) indicate a rich one-sided jet structure extending to 80 mas. Here we analyse simultaneously made sensitive 1.7- and 5-GHz archive VLBI images as well as snapshot 8.4/8.7-GHz VLBI images of J1918+4937, and show that the appearance of the wiggled jet is consistent with the binary scenario. We develop a jet structural model that handles eccentric orbits. By applying this model to the measured VLBI component positions, we constrain the inclination of the radio jet, as well as the spin angle of the jet emitter SMBH. We find the jet morphological model is consistent with the optical and radio data, and that the secondary SMBH is most likely the jetted one in the system. Furthermore, the decade-long 15-GHz radio flux density monitoring data available for J1918+4937 are compatible with a gradual overall decrease in the total flux density caused by a slow secular change of the jet inclination due to the spin–orbit precession. J1918+4937 could be an efficient high-energy neutrino source if the horizon of the secondary SMBH is rapidly rotating.

scholarly journals Fifty Years of Energy Extraction from Rotating Black Hole: Revisiting Magnetic Penrose Process

Universe ◽  
2019 ◽  
Vol 5 (5) ◽  
pp. 125 ◽  
Author(s):  
Arman Tursunov ◽  
Naresh Dadhich
Keyword(s):  
Black Hole ◽  
Process Mining ◽  
Thought Experiment ◽  
High Energy ◽  
Radio Bursts ◽  
Ultra High Energy ◽  
Relativistic Jets ◽  
High Energy Cosmic Rays ◽  
Penrose Process ◽  
Viable Mechanism

Magnetic Penrose process (MPP) is not only the most exciting and fascinating process mining the rotational energy of black hole but it is also the favored astrophysically viable mechanism for high energy sources and phenomena. It operates in three regimes of efficiency, namely low, moderate and ultra, depending on the magnetization and charging of spinning black holes in astrophysical setting. In this paper, we revisit MPP with a comprehensive discussion of its physics in different regimes, and compare its operation with other competing mechanisms. We show that MPP could in principle foot the bill for powering engine of such phenomena as ultra-high-energy cosmic rays, relativistic jets, fast radio bursts, quasars, AGNs, etc. Further, it also leads to a number of important observable predictions. All this beautifully bears out the promise of a new vista of energy powerhouse heralded by Roger Penrose half a century ago through this process, and it has today risen in its magnetically empowered version of mid 1980s from a purely thought experiment of academic interest to a realistic powering mechanism for various high-energy astrophysical phenomena.

Extragalactic relativistic jets

2018 ◽  
Vol 14 (S342) ◽  
pp. 61-68
Author(s):  
Monica Orienti
Keyword(s):  
Gamma Ray ◽  
High Energy ◽  
High Angular Resolution ◽  
Electromagnetic Spectrum ◽  
Relativistic Jets ◽  
Energy Bands ◽  
Large Area ◽  
Energy Emission ◽  
Radio Band ◽  
High Energy Emission

AbstractRelativistic jets are one of the most powerful manifestations of the release of energy produced around supermassive black holes at the centre of active galactic nuclei (AGN). Their emission is observed across the entire electromagnetic spectrum, from the radio band to gamma rays. Despite decades of efforts, many aspects of the physics of relativistic jets remain elusive. In particular, the location and the mechanisms responsible for the high-energy emission and the connection of the variability at different wavelengths are among the greatest challenges in the study of AGN. Recent high resolution radio observations of flaring objects locate the high energy emitting region downstream the jet at parsec scale distance from the central engine. Furthermore, monitoring campaigns of the most active blazars indicate that not all the high energy flares have the same characteristics in the various energy bands, even from the same source, making the interpretation of the mechanism responsible for the high-energy emission not trivial. Here I will discuss gamma-ray properties of blazars obtained by Fermi Large Area Telescope observations and the connection between radio and high-energy emission in relativistic jets, and I will focus on the importance of high angular resolution observations.

scholarly journals Multi-wavelength characterization of the blazar S5 0716+714 during an unprecedented outburst phase

2018 ◽  
Vol 619 ◽  
pp. A45 ◽  
Author(s):  
◽  
M. L. Ahnen ◽  
S. Ansoldi ◽  
L. A. Antonelli ◽  
C. Arcaro ◽  
...  
Keyword(s):  
Position Angle ◽  
High Energy ◽  
Spectral Energy ◽  
Zone Model ◽  
Energy Bands ◽  
Broadband Emission ◽  
Multi Wavelength ◽  
Very High Energy ◽  
Radio Band ◽  
Optical Flux

Context. The BL Lac object S5 0716+714, a highly variable blazar, underwent an impressive outburst in January 2015 (Phase A), followed by minor activity in February (Phase B). The MAGIC observations were triggered by the optical flux observed in Phase A, corresponding to the brightest ever reported state of the source in the R-band. Aims.The comprehensive dataset collected is investigated in order to shed light on the mechanism of the broadband emission. Methods. Multi-wavelength light curves have been studied together with the broadband spectral energy distributions (SEDs). The sample includes data from Effelsberg, OVRO, Metsähovi, VLBI, CARMA, IRAM, SMA, Swift-UVOT, KVA, Tuorla, Steward, RINGO3, KANATA, AZT-8+ST7, Perkins, LX-200, Swift-XRT, NuSTAR, Fermi-LAT and MAGIC. Results. The flaring state of Phase A was detected in all the energy bands, providing for the first time a multi-wavelength sample of simultaneous data from the radio band to the very-high-energy (VHE, E > 100 GeV). In the constructed SED, the Swift-XRT+NuSTAR data constrain the transition between the synchrotron and inverse Compton components very accurately, while the second peak is constrained from 0.1 GeV to 600 GeV by Fermi+MAGIC data. The broadband SED cannot be described with a one-zone synchrotron self-Compton model as it severely underestimates the optical flux in order to reproduce the X-ray to γ-ray data. Instead we use a two-zone model. The electric vector position angle (EVPA) shows an unprecedented fast rotation. An estimation of the redshift of the source by combined high-energy (HE, 0.1 GeV < E < 100 GeV) and VHE data provides a value of z = 0.31 ± 0.02stats ± 0.05sys, confirming the literature value. Conclusions. The data show the VHE emission originating in the entrance and exit of a superluminal knot in and out of a recollimation shock in the inner jet. A shock–shock interaction in the jet seems responsible for the observed flares and EVPA swing. This scenario is also consistent with the SED modeling.

scholarly journals The central pc-scale region in blazars: insights from multi-band observations

2013 ◽  
Vol 9 (S304) ◽  
pp. 257-260
Author(s):  
Tigran G. Arshakian ◽  
Vahram Chavushyan
Keyword(s):  
Black Hole ◽  
High Energy ◽  
Opening Angle ◽  
Radiation Mechanisms ◽  
Long Baseline ◽  
Empirical Relations ◽  
Relativistic Jet ◽  
Line Region ◽  
Γ Ray ◽  
Very Long Baseline Array

AbstractThe empirical relations in the black hole-accretion disk-relativistic jet system and physical processes behind these relations are still poorly understood, partly because they operate close to the black hole within the central light year. Very long baseline array (VLBA) provides unparalleled resolution at 15 GHz with which to observe the jet components at sub-milliarcsecond scales, corresponding to sub-pc-scales for local blazars. We discuss the jet inner structure of blazars, location and radiation mechanisms operating in the innermost parsec-scale region of blazars, and evidence for jet-excited broad-line region (BLR) ouflowing downstream the jet. Outflowing BLR can provide necessary conditions for production of high energy emission along the jet between the base of the jet and the BLR and far beyond the BLR as evidenced by recent observations. Flat spectrum quasars and low synchrotron peaked sources are the most likely objects to host the outfllowing BLR. From the γ-ray absorption arguments, we propose that the jet-excited region of the outflowing BLR in quasars is small and/or gas filling factor is low, and that the orientation and opening angle of the outflowing BLR can lead to relevant γ-ray absorption features observed in quasars.

scholarly journals Structure formation of black hole jets triggered by electron-scale physics

2020 ◽  
Author(s):  
Tomohisa Kawashima ◽  
Seiji Ishiguro ◽  
Toseo Moritaka ◽  
Ritoku Horiuchi ◽  
Kohji Tomisaka
Keyword(s):  
Black Hole ◽  
Structure Formation ◽  
Elliptical Galaxy ◽  
High Energy ◽  
Shear Instability ◽  
Relativistic Jets ◽  
Ridge Structure ◽  
Sheath Region ◽  
High Energy Electrons ◽  
Relativistic Jet

Abstract Jets are ubiquitous in the universe[1,2]. The radio jet is a beamed plasma flow with relativistic speed accelerated by a supermassive black hole in some galaxies. Recent observations of the relativistic jet in the elliptical galaxy M87 have discovered a triple-ridge sub-structure in the jet at a distance of one thousand Schwartzchild radius from the black hole [3,4]. The triple-ridge structure may be the first strong evidence of the spine-sheath structure consisting of the fast spine region (jet spine) and relatively slow sheath region (jet sheath), which was hypothetically introduced to explain observational features in various unresolved relativistic jets [5,6]. However, the formation mechanism of such a spine-brightened jet is quite enigmatic. Here we report that the combination of the magnetic pinching force induced by an electron-scale shear-instability called Mushroom instability[7] and the high-energy electron ejections by the subsequent magnetic reconnection leads to the drastic accumulation of high-energy electrons in the center of the cylindrical jet. The concentration of high-energy electrons towards the jet center indicates the appearance of bright jet-spine as observed in M87. Thus, the electron-scale, microscopic processes would play an important role in the structure formation and generation of high-energy components in the relativistic jets. Rererences: [1] Frank, A. etal. Jets and Outflows from Star to Cloud: Observations ConfrontTheory. InBeuther, H., Klessen, R. S., Dullemond, C. P. & Henning, T. (eds.) Protostars and Planets VI, 451 (2014). [2] Blandford, R., Meier, D. & Readhead, A. Relativistic Jets from Active Galactic Nuclei. ARA&A 57, 467–509 (2019). [3] Asada, K., Nakamura, M. & Pu, H.-Y. Indication of the Black Hole Powered Jet in M87 by VSOP Observations. ApJ833, 56 (2016). [4] Hada, K. The Structure and Propagation of the Misaligned Jet M87. Galaxies 5, 2 (2017). [5] Laing, R. A. & Bridle, A. H. Relativistic models and the jet velocity field in the radio galaxy3C 31. MNRAS 336, 328–352 (2002). [6] Ghisellini, G., Tavecchio, F. & Chiaberge, M. Structured jets in TeV BL Lac objectsand radiogalaxies. Implications for the observed properties. A&A 432, 401–410 (2005). [7] Alves, E. P., Grismayer, T., Fonseca, R. A. & Silva, L. O. Transverse electron-scale instability in relativistic shear flows. PhRvE 92, 021101 (2015).

scholarly journals WISDOM project – VII. Molecular gas measurement of the supermassive black hole mass in the elliptical galaxy NGC 7052

2021 ◽  
Vol 503 (4) ◽  
pp. 5984-5996
Author(s):  
Mark D Smith ◽  
Martin Bureau ◽  
Timothy A Davis ◽  
Michele Cappellari ◽  
Lijie Liu ◽  
...  
Keyword(s):  
Black Hole ◽  
Hubble Space Telescope ◽  
Elliptical Galaxy ◽  
Continuum Emission ◽  
Molecular Gas ◽  
Supermassive Black Hole ◽  
Gas Kinematics ◽  
Long Baseline ◽  
Gas Measurement ◽  
Strong Gradient

ABSTRACT Supermassive black hole (SMBH) masses can be measured by resolving the dynamical influences of the SMBHs on tracers of the central potentials. Modern long-baseline interferometers have enabled the use of molecular gas as such a tracer. We present here Atacama Large Millimeter/submillimeter Array observations of the elliptical galaxy NGC 7052 at 0${^{\prime\prime}_{.}}$11 ($37\,$pc) resolution in the 12CO(2-1) line and $1.3\,$ mm continuum emission. This resolution is sufficient to resolve the region in which the potential is dominated by the SMBH. We forward model these observations, using a multi-Gaussian expansion of a Hubble Space Telescope F814W image and a spatially constant mass-to-light ratio to model the stellar mass distribution. We infer an SMBH mass of $2.5\pm 0.3\times 10^{9}\, \mathrm{M_\odot }$ and a stellar I-band mass-to-light ratio of $4.6\pm 0.2\, \mathrm{M_\odot /L_{\odot ,I}}$ (3σ confidence intervals). This SMBH mass is significantly larger than that derived using ionized gas kinematics, which however appears significantly more kinematically disturbed than the molecular gas. We also show that a central molecular gas deficit is likely to be the result of tidal disruption of molecular gas clouds due to the strong gradient in the central gravitational potential.

scholarly journals A radio parallax to the black hole X-ray binary MAXI J1820+070

2020 ◽  
Vol 493 (1) ◽  
pp. L81-L86 ◽  
Author(s):  
P Atri ◽  
J C A Miller-Jones ◽  
A Bahramian ◽  
R M Plotkin ◽  
A T Deller ◽  
...  
Keyword(s):  
Black Hole ◽  
Inclination Angle ◽  
Precise Measurement ◽  
Very Long Baseline Interferometry ◽  
X Ray ◽  
Long Baseline ◽  
Model Independent ◽  
Jet Velocity ◽  
Very Long Baseline Array

ABSTRACT Using the Very Long Baseline Array and the European Very Long Baseline Interferometry Network, we have made a precise measurement of the radio parallax of the black hole X-ray binary MAXI J1820+070, providing a model-independent distance to the source. Our parallax measurement of (0.348 ± 0.033) mas for MAXI J1820+070 translates to a distance of (2.96 ± 0.33) kpc. This distance implies that the source reached (15 ± 3) per cent of the Eddington luminosity at the peak of its outburst. Further, we use this distance to refine previous estimates of the jet inclination angle, jet velocity, and the mass of the black hole in MAXI J1820+070 to be (63 ± 3)°, (0.89 ± 0.09) c, and (9.2 ± 1.3) M⊙, respectively.

OBSERVATIONAL CONSTRAINTS ON STRONG GRAVITY

2011 ◽  
Vol 20 (14) ◽  
pp. 2755-2760
Author(s):  
CHRIS DONE
Keyword(s):  
Black Hole ◽  
Event Horizon ◽  
Strong Field ◽  
Field Tests ◽  
High Energy ◽  
Observational Constraints ◽  
Tests Of General Relativity ◽  
Strong Gravity ◽  
Accretion Flows ◽  
Spacetime Curvature

Accretion onto a black hole transforms the darkest objects in the universe to the brightest. The high energy radiation emitted from the accretion flow before it disappears forever below the event horizon lights up the regions of strong spacetime curvature close to the black hole, enabling strong field tests of General Relativity. I review the observational constraints on strong gravity from such accretion flows, and show how the data strongly support the existence of such fundamental General Relativistic features of a last stable orbit and the event horizon. However, these successes also imply that gravity does not differ significantly from Einstein's predictions above the event horizon, so any new theory of quantum gravity will be very difficult to test.

Sign in / Sign up

Export Citation Format

Share Document