Advection-Dominated Accretion Model of Sagittarius A*: Evidence for a Black Hole at the Galactic Center

Abstract

Sgr A* at the Galactic Center is a puzzling source. It has a mass M=(2.5+/-0.4) x 10^6 solar masses which makes it an excellent black hole candidate. Observations of stellar winds and other gas flows in its vicinity suggest a mass accretion rate approximately few x 10^{-6} solar masses per year. However, such an accretion rate would imply a luminosity > 10^{40} erg/s if the radiative efficiency is the usual 10 percent, whereas observations indicate a bolometric luminosity <10^{37} erg/s. The spectrum of Sgr A* is unusual, with emission extending over many decades of wavelength. We present a model of Sgr A* which is based on a two-temperature optically-thin advection-dominated accretion flow. The model is consistent with the estimated mass and accretion rate, and fits the observed fluxes in the cm/mm and X-ray bands as well as upper limits in the sub-mm and infrared bands; the fit is less good in the radio below 86 GHz and in gamma-rays above 100 MeV. The very low luminosity of Sgr A* is explained naturally in the model by means of advection. Most of the viscously dissipated energy is advected into the central mass by the accreting gas, and therefore the radiative efficiency is extremely low, approximately 5 x 10^{-6}. A critical element of the model is the presence of an event horizon at the center which swallows the advected energy. The success of the model could thus be viewed as confirmation that Sgr A* is a black hole.

41 pages (Latex) including 6 Figures and 2 Tables. Final Revised Version changes to text, tables and figures. ApJ, 492, in press

References in corpus (25)

• Advection-Dominated Accretion: A Self-Similar Solution
• Advection-Dominated Accretion: Underfed Black Holes and Neutron Stars
• Advection-Dominated Accretion and the Spectral States of Black Hole X-Ray Binaries: Application to Nova Muscae 1991
• Advection-Dominated Accretion: Self-Similarity and Bipolar Outflows
• Thermal Equilibria of Accretion Disks
• The Two-Phase Pair Corona Model for Active Galactic Nuclei and X-ray Binaries: How to Obtain Exact Solutions
• Scaling Laws for Advection Dominated Flows: Applications to Low Luminosity Galactic Nuclei
• A New Model for Black Hole Soft X-ray Transients in Quiescence
• Global Structure and Dynamics of Advection-Dominated Accretion Flows Around Black Holes
• Advection-Dominated Accretion and Black Hole Event Horizons
• Spectrum of Optically Thin Advection Dominated Accretion Flow around a Black Hole: Application to Sgr A*
• Advection-Dominated Accretion Model of the Black Hole V404 Cyg in Quiescence
• The `quiescent' black hole in M87
• Is the Accretion Flow in NGC 4258 Advection-dominated?
• Unified Description of Accretion Flows Around Black Holes
• Advection Dominated Accretion Flows Around Kerr Black Holes
• Harmony in Electrons: Cyclotron and Synchrotron Emission by Thermal Electrons in a Magnetic Field
• Viscous accretion discs around rotating black holes
• Are Particles in Advection-Dominated Accretion Flows Thermal?
• Advection-Dominated Flows and the X-ray Delay in the Outburst of GRO J1655-40
• Advection-dominated accretion: global transonic solutions
• Gamma-ray Emission From Advection-Dominated Accretion Flows Around Black Holes: Application to the Galactic Center
• Heating and Cooling of Hot Accretion Flows by Non Local Radiation
• Accretion Disk Evolution With Wind Infall I. General Solution and Application to Sgr A*
• Thermal Instability of Advection-Dominated Disks against Local Perturbations

Cited by in corpus (287)

• Particle Dark Matter: Evidence, Candidates and Constraints
• Hot Accretion Flows Around Black Holes
• The Galactic Center Massive Black Hole and Nuclear Star Cluster
• Sources of Relativistic Jets in the Galaxy
• Present-Day Growth of Black Holes and Bulges: the SDSS Perspective
• Chandra X-ray Spectroscopic Imaging of Sgr A* and the Central Parsec of the Galaxy
• Nonthermal Electrons in Radiatively Inefficient Accretion Flow Models of Sagittarius A*
• First Sagittarius A* Event Horizon Telescope Results. VI: Testing the Black Hole Metric
• Active Galactic Nuclei: what's in a name?
• Rapid X-ray flaring from the direction of the supermassive black hole at the Galactic Centre
• Going with the flow: can the base of jets subsume the role of compact accretion disk coronae?
• First Sagittarius A* Event Horizon Telescope Results. V. Testing Astrophysical Models of the Galactic Center Black Hole
• The Supermassive Black Hole at the Galactic Center
• Advection-Dominated Accretion and the Black Hole Event Horizon
• Very high energy gamma rays from the direction of Sagittarius A*
• Hydrodynamical Non-radiative Accretion Flows in Two-Dimensions
• On the Relationship Between Radio Emission and Black Hole Mass in Galactic Nuclei
• The Event Horizon General Relativistic Magnetohydrodynamic Code Comparison Project
• Radio-loud Narrow-Line Type 1 Quasars
• Radiative Models of Sgr A* from GRMHD Simulations
• Spectral Transitions in Cyg X-1 and Other Black Hole X-Ray Binaries
• A Jet-ADAF model for Sgr A*
• Interferometric Detection of Linear Polarization from Sagittarius A* at 230 GHz
• Spectral Models of Advection-Dominated Accretion Flows with Winds
• New Evidence for Black Hole Event Horizons from Chandra
• Black Holes in Astrophysics
• Black Hole and Neutron Star Transients in Quiescence
• The Nature of the 10 Kilosecond X-ray Flare in Sgr A*
• Testing the No-Hair Theorem with Event Horizon Telescope Observations of Sagittarius A*
• The Coincidence of Nuclear Star Clusters and Active Galactic Nuclei
• Particle Heating by Alfvenic Turbulence in Hot Accretion Flows
• X-Ray and Optical Variability in NGC 4051 and the Nature of Narrow-Line Seyfert 1 Galaxies
• XMM-Newton observation of the brightest X-ray flare detected so far from SgrA*
• A wide star-black-hole binary system from radial-velocity measurements
• Detection of the Intrinsic Size of Sagittarius A* through Closure Amplitude Imaging (includes Online Supporting Material)
• A refined sub-grid model for black hole accretion and AGN feedback in large cosmological simulations
• Constraining the Accretion Rate Onto Sagittarius A* Using Linear Polarization
• On The Nature of the Variable Infrared Emission from Sgr A*
• An Accretion-Jet Model for Black Hole Binaries: Interpreting the Spectral and Timing Features of XTE J1118+480
• Evidence for Low Black Hole Spin and Physically Motivated Accretion Models from Millimeter VLBI Observations of Sagittarius A*
• Testing General Relativity with the Shadow Size of Sgr A*
• Flaring Activity of Sgr A* at 43 and 22 GHz: Evidence for Expanding Hot Plasma
• The Intrinsic Size of Sagittarius A* from 0.35 cm to 6 cm
• Sagittarius A* Accretion Flow and Black Hole Parameters from General Relativistic Dynamical and Polarized Radiative Modeling
• Modeling the Low State Spectrum of the X-Ray Nova XTE J1118+480
• Hybrid Thermal-Nonthermal Synchrotron Emission from Hot Accretion Flows
• Black hole accretion disks in the canonical low-hard state
• BlackHoleCam: fundamental physics of the Galactic center
• Methods for detecting flaring structures in Sagittarius A* with high frequency VLBI
• Accretion disc onto a static non-baryonic compact object
• The Nature of X-ray Bright Optically Normal Galaxies
• The role of electron heating physics in images and variability of the Galactic Centre black hole Sagittarius A*
• Radio Sources in Low-Luminosity Active Galactic Nuclei. II. VLBI Detections of Compact Radio Cores and Jets in a Sample of LINERs
• X-ray constraints on the local supermassive black hole occupation fraction
• The Power of Imaging: Constraining the Plasma Properties of GRMHD Simulations using EHT Observations of Sgr A*
• Plasma diagnostic potential of 2p4f in N${}^{+}$ -- accurate wavelengths and oscillator strengths
• Estimating the Parameters of Sgr A*'s Accretion Flow Via Millimeter VLBI
• The VLA-COSMOS 3~GHz Large Project: Cosmic evolution of radio AGN and implications for radio-mode feedback since z~5
• X-ray hiccups from SgrA* observed by XMM-Newton. The second brightest flare and three moderate flares caught in half a day
• A powerful flare from Sgr A* confirms the synchrotron nature of the X-ray emission
• Sgr A* and General Relativity
• The Milky Way's Supermassive Black Hole: How good a case is it? A Challenge for Astrophysics & Philosophy of Science
• Towards the event horizon -- the supermassive black hole in the Galactic Center
• Intrinsic Size OF Sgr A*: 72 Schwarzschild Radii
• Luminous hot accretion disks
• Variability of Sagittarius A* - Flares at 1 Millimeter
• Simulations of Electron Magnetohydrodynamic Turbulence
• Evidence for Jet Domination of the Nuclear Radio Emission in Low-luminosity Active Galactic Nuclei
• 230 GHz VLBI observations of M87: event-horizon-scale structure at the enhanced very-high-energy $\gamma$-ray state in 2012
• A New X-Ray Flare from the Galactic Nucleus Detected with the XMM-Newton Photon Imaging Cameras
• Multi-wavelength signals of dark matter annihilations at the Galactic center
• Simultaneous Chandra, CSO and VLA Observations of Sgr A*: The Nature of Flaring Activity
• Ab Initio Horizon-Scale Simulations of Magnetically Arrested Accretion in Sagittarius A* Fed by Stellar Winds
• Simultaneous Multi-Wavelength Observations of Sgr A* during 2007 April 1-11
• Proper Motion of the Compact, Nonthermal Radio Source in the Galactic Center, Sagittarius a*
• What is the Accretion Rate in NGC 4258?
• Simulations of the heating of the Galactic stellar disc
• No Evidence for Intermediate-Mass Black Holes in Globular Clusters: Strong Constraints from the JVLA
• Advection Dominated Accretion Flows in the Kerr Metric: II. Steady State Global Solutions
• Results from an extensive simultaneous broadband campaign on the underluminous active nucleus M81*: further evidence for mass-scaling accretion in black holes
• How to hide large scale outflows: size constraints on the jets of Sgr A*
• Circular Polarization of Radio Emission from Relativistic Jets
• Thermal synchrotron radiation and its Comptonization in compact X-ray sources
• Faraday rotation in GRMHD simulations of the jet launching zone of M87
• The Event Horizon of M87
• Unprecedented variability of Sgr A* in NIR
• Detection of Circular Polarization in the Galactic Center Black Hole Candidate Sagittarius A*
• Hybrid-Kinetic Simulations of Ion Heating in Alfvénic Turbulence
• A Stationary Core with a One-sided Jet in the Center of M81
• Annihilation Radiation from a Dark Matter Spike at the Galactic Centre
• Radiatively Inefficient Accretion Flow Models of Sgr A*
• A census of X-ray nuclear activity in nearby galaxies
• Two-Temperature GRRMHD Simulations of M87
• A Thermal Bremsstrahlung Model For the Quiescent X-ray Emission from Sagittarius A*
• X-ray bubbles in the circumgalactic medium of TNG50 Milky Way- and M31-like galaxies: signposts of supermassive black hole activity
• Spoon-Feeding Giant Stars to Supermassive Black Holes: Episodic Mass Transfer from Evolving Stars and Their Contribution to the Quiescent Activity of Galactic Nuclei
• Electron Heating by the Ion Cyclotron Instability in Collisionless Accretion Flows. I. Compression-Driven Instabilities and the Electron Heating Mechanism
• NuSTAR detection of high-energy X-ray emission and rapid variability from Sagittarius A* flares
• Simulations of imaging the event horizon of Sagittarius A* from space
• Covariant Magnetoionic Theory I: Ray Propagation
• Neutralino Annihilation at the Galactic Center Revisited
• The Zoo of X-ray sources in the Galactic Center Region: Observations with BeppoSAX
• What is the Accretion Rate in Sgr A*?
• Astrophysical Limits on Massive Dark Matter
• The Nature of the Molecular Environment within 5 pc of the Galactic Center
• Testing General Relativity with Accretion-Flow Imaging of Sgr A*
• The Linear Polarization of Sagittarius A* I. VLA Spectro-polarimetry at 4.8 and 8.4 GHz
• Jet-lag in Sgr A*: What size and timing measurements tell us about the central black hole in the Milky Way
• The Radiative Efficiency and Spectra of Slowly Accreting Black Holes from Two-Temperature GRRMHD Simulations
• The Atlas3D project -- XXXI. Nuclear radio emission in nearby early-type galaxies
• VLBA Continuum Observations of NGC 4258: Constraints on an Advection-Dominated Accretion Flow
• A hidden friend for the galactic center black hole, Sgr A*
• Hot Accretion With Conduction: Spontaneous Thermal Outflows
• Low-Luminosity AGNs at the Highest Resolution: Jets or Accretion Flows?
• Global Dynamics of Advection-Dominated Accretion Revisited
• Either neutralino dark matter or cuspy dark halos
• The Limitations of Optical Spectroscopic Diagnostics in Identifying AGNs in the Low Mass Regime
• Three-Dimensional Moving-Mesh Simulations of Galactic Center Cloud G2
• The Megasecond Chandra XVP Observation of NGC 3115: Witnessing the Flow of Hot Gas within the Bondi Radius
• MHD Simulations of Accretion onto Sgr A*: Quiescent Fluctuations, Outbursts, and Quasi-Periodicity
• Evolving Nonthermal Electrons in Simulations of Black Hole Accretion
• The Galactic Center: An Interacting System of Unusual Sources
• Constraining the charge of the Galactic centre black hole
• Discovery of Substructure in the Scatter-Broadened Image of Sgr A*
• On the LINER nuclear obscuration, Compton-thickness and the existence of the dusty torus; Clues from Spitzer/IRS spectra
• A Population of Faint Non-Transient Low Mass Black Hole Binaries
• Optical and X-ray Variability in The Least Luminous AGN, NGC4395
• Black hole mass and binary model for BL Lac object OJ 287
• High Radio Frequency Properties and Variability of Brightest Cluster Galaxies
• The Linear Polarization of Sagittarius A* II. VLA and BIMA Polarimetry at 22, 43 and 86 GHz
• Thermal X-Ray Line Emission from Accreting Black Holes
• Physical laboratory at the center of the Galaxy
• The Circular Polarization of Sagittarius A* at Submillimeter Wavelengths
• On the Energetics of Advection-Dominated Accretion Flows
• Constraint on the quadrupole moment of super-massive black hole candidates from the estimate of the mean radiative efficiency of AGN
• Possible Origin of the G2 Cloud from the Tidal Disruption of a Known Giant Star by Sgr A*
• A power-law break in the near-infrared power spectrum of the Galactic center black hole
• Effect of Electromagnetic Interaction on Galactic Center Flare Components
• Black Hole Starvation and Bulge Evolution in a Milky Way-like Galaxy
• Estimating the parameters of the Sgr A* black hole
• Self-consistent spectra from radiative GRMHD simulations of accretion onto Sgr A*
• Spectral and Imaging properties of Sgr A* from High-Resolution 3D GRMHD Simulations with Radiative Cooling
• The Survey of Nearby Nuclei with STIS (SUNNS):Emission-Line Nuclei at Hubble Space Telescope Resolution
• Preheated Advection Dominated Accretion Flow
• Images of the radiatively inefficient accretion flow surrounding a Kerr black hole: application in Sgr A*
• Unbound Debris Streams and Remnants Resulting From the Tidal Disruptions of Stars by Supermassive Black Holes
• X-Ray Flares and Oscillations from the Black Hole Candidate X-Ray Transient XTE J1650-500 at Low Luminosity
• The origin of hotspots around Sgr A*: Orbital or pattern motion?
• Gravitational Deflection of Light and Massive Particle by a Moving Kerr-Newman Black Hole
• The Quiescent Emission Spectrum of Cen X-4 and other X-ray Transients containing Neutron Stars
• Faraday Rotation in Global Accretion Disk Simulations: Implications for Sgr A*
• Evidence for nuclear radio jet and its structure down to <100 Schwarzschild radii in the center of the Sombrero galaxy (M 104, NGC 4594)
• Time-dependent quasi-spherical accretion
• The Structure of Radiatively Inefficient Black Hole Accretion Flows
• Testing RIAF model for Sgr A* using the size measurements
• The motion of stars near the Galactic center: A comparison of the black hole and fermion ball scenarios
• The role of the outer boundary condition in accretion disk models: theory and application
• Exploring plasma evolution during Sagittarius A* flares
• Near-Infrared Polarimetric Adaptive Optics Observations of NGC 1068: A torus created by a hydromagnetic outflow wind
• From Multiwavelength to Mass Scaling: Accretion and Ejection in Microquasars and AGN
• Electron Heating by the Ion Cyclotron Instability in Collisionless Accretion Flows. II. Electron Heating Efficiency as a Function of Flow Conditions
• The flat X-ray spectrum of the LINER NGC1052
• Temperature properties in magnetised and radiatively cooled two-temperature accretion flows onto a black hole
• Radio morphology-accretion mode link in FRII low-excitation radio galaxies
• Multiwavelength study of the flaring activity of Sgr A* in 2014 February-April
• Scale-invariant radio jets and varying black hole spin
• The Effects of Tilt on the Images of Black Hole Accretion Flows
• Quantifying Intrinsic Variability of Sagittarius A* using Closure Phase Measurements of the Event Horizon Telescope
• Sagittarius A* High Energy X-ray Flare Properties During NuSTAR Monitoring of the Galactic Center from 2012 to 2015
• Analytic Model for Advection-Dominated Accretion Flows in a Global Magnetic Field
• The Observed Galactic Annihilation Line. Possible Signature of the Cluster for Accreting Small Mass Black Holes
• General relativistic magnetohydrodynamic dynamo in thick accretion disks: fully nonlinear simulations
• Dwarf AGNs from Variability for the Origins of Seeds (DAVOS): Intermediate-mass black hole demographics from optical synoptic surveys
• Properties of Accretion Flows Around Coalescing Supermassive Black Holes
• Global solution of viscous accretion disk around rotating compact objects: a pseudo-general-relativistic study
• Is there an intermediate massive black hole in the Galactic center: Imprints on the stellar tidal-disruption rate
• Stability of accretion disk around rotating black holes: a pseudo-general-relativistic fluid dynamical study
• Bayesian techniques for comparing time-dependent GRMHD simulations to variable Event Horizon Telescope observations
• VLBA Observations of Astrometric Reference Sources in the Galactic Center
• A time-dependent jet model for the emission from Sagittarius A*
• Observational evidence for the formation of trapping horizons in astrophysical black holes
• Study of the Gamma-ray Spectrum from the Galactic Center in view of Multi-TeV Dark Matter Candidates
• The X-ray spectrum of NGC 7213 and the Seyfert--LINER connection
• Particle Heating by Nonlinear Alfvenic Turbulence in ADAFs
• $NuSTAR$ Observations of Four Nearby X-ray Faint AGN: Low Luminosity or Heavy Obscuration?
• Fitting the light curves of Sagittarius A* with a hot-spot model
• Advection-dominated Inflow/Outflows from Evaporating Accretion Disks
• Spectral properties of Three-dimensional Magneto-hydrodynamical Accretion Flows
• Hunting for wandering massive black holes
• Origin of Radio Emission from Nearby Low-Luminosity Active Galactic Nuclei
• A "coronal-mass-ejection'' model for flares in Sagittarius A*
• The Effects of Gas Angular Momentum on the Formation of Magnetically Arrested Disks and the Launching of Powerful Jets
• High Resolution Radio Astronomy Using Very Long Baseline Interferometry
• Polarization images of accretion flow around supermassive black holes: imprints of toroidal field structure
• Study of the X-ray activity of Sgr A* during the 2011 XMM-Newton campaign
• Accretion of Low Angular Momentum Material onto Black Holes: Radiation Properties of Axisymmetric MHD Flows
• Simultaneous Monitoring of X-ray and Radio Variability in Sagittarius A*
• Probing the Two-Temperature Paradigm: Observational Tests for the Basic Assumptions in ADAFs
• Looking for the underlying cause of black hole X-ray variability in GRMHD simulations
• The Role of Magnetic Field Dissipation in the Black Hole Candidate Sgr A*
• Nonthermal processes in hot accretion flows onto supermassive black holes: An inhomogeneous model
• X-ray Probes of Black Hole Accretion Disks for Testing the No-Hair Theorem
• Thermal Properties of Two-Dimensional Advection Dominated Accretion Flow
• Universal transition diagram from dormant to actively accreting supermassive black holes
• Multi-Epoch VERA Observations of Sagittarius A*: I. Images and Structural Variability
• Where have all the black holes gone?
• Hot Molecular Gas in the Circumnuclear Disk
• Observational signatures from horizonless black shells imitating rotating black holes
• Gravitational lensing of massive particles by a black-bounce-Schwarzschild black hole
• Low angular momentum flow model for Sgr A*
• No asymmetric outflows from Sagittarius A* during the pericenter passage of the gas cloud G2
• A thin diffuse component of the Galactic Ridge X-ray emission and heating of the interstellar medium contributed by the radiation of Galactic X-ray binaries
• Gamma-ray emission from proton-proton interactions in hot accretion flows
• Constraining the accretion flow density profile near Sgr A* using the $L^{\prime }$-band emission of the S2 star
• Advection-Dominated Accretion with Infall and Outflows
• Determining AGN luminosity histories using present-day outflow properties: a neural-network based approach
• Dynamics of Hot Accretion Flow with Thermal Conduction
• Multiple accretion events as a trigger for Sgr A* activity
• Low angular momentum flow model II for Sgr A*
• Astrophysical constraints on a possible neutrino ball at the Galactic Center
• Repeating Partial Tidal Encounters of Sun-like Stars Leading to their Complete Disruption
• Spherically Symmetric Accretion Flows: Minimal Model with MHD Turbulence
• Possible evidence for the disk origin for the powering of jets in Sgr A* and nearby elliptical galaxies
• Modeling the time-resolved quasi-periodic oscillations in AGNs
• Radiation Spectra from Advection-Dominated Accretion Flows in a Global Magnetic Field
• Neutrino lighthouse powered by Sagittarius A* disk dynamo
• Gamma-rays as a diagnostic of the origin of core radiation in low-luminosity active galactic nuclei
• The advection-dominated accretion flow+thin accretion disk model for two low-luminosity active galactic nuclei: M81 and NGC4579
• ADAFs -- Models, Observations and Problems
• Dusty plasma in active galactic nuclei
• Pinpointing the massive black hole in the Galactic Center with gravitationally lensed stars
• Heavy neutrino ball as a possible solution to the "blackness problem" of the Galactic center
• Monitoring the Galactic Centre with Australia Telescope Compact Array
• The Nature of Linearly Polarized Millimeter and Sub-millimeter Emission in Sagittarius A*
• Accretion models of Sgr A*
• ROSAT Blank Field Sources I: Sample Selection and Archival Data
• Cosmic rays from the nearby starburst galaxy NGC 253: the effect of a low luminosity active galactic nucleus
• The Influence of Hydrodynamical Winds on Hot Accretion Disk Solutions
• Activity From Tidal Disruptions in Galactic Nuclei
• Magnetized Accretion Flows: Effects of Gas Pressure
• Coronal Properties of Low-Accreting AGNs using Swift, XMM-Newton and NuSTAR Observations
• Three-dimensional Radiative Properties of Hot Accretion Flows onto the Galactic Centre Black Hole
• Confronting the jet model of Sgr A* with the Faraday rotation measure observations
• Spherical Accretion in Nearby Weakly Active Galaxies
• Variability of NGC 4051 and the Nature of Narrow-Line Seyfert 1 Galaxies
• Effects of Hydrogen vs. Helium on Electromagnetic Black Hole Observables
• Kerr-Newman black hole lensing of relativistic massive particles in the weak field limit
• Mass Limits on Neutralino Dark Matter
• Reprocessing of radiation by multi-phase gas in Low Luminosity Accretion Flows
• Blob formation and ejection from the radiative inefficient accretion flow around massive black hole
• Accretion and jets in a low luminosity AGN: the nucleus of NGC 1052
• X-ray and radio observations of central black holes in nearby low-mass early-type galaxies: Preliminary evidence for low Eddington fractions
• Resolving the Nuclear Radio Emission from M32 with Very Large Array
• Constraints on jet-driven disk accretion in Sagittarius A*
• Theory of disk accretion onto supermassive black holes
• The Effects of Tilt on the Time Variability of Millimeter and Infrared Emission from Sagittarius A*
• Electromagnetic signatures of strong-field gravity from accreting black holes
• Effect of Coriolis force on Accretion Flows around Rotating Compact Object
• The Evaporating Massive Embedded Stellar Cluster IRS 13 Close to Sgr A*. II. Kinematic structure
• Sculpting the Stellar Cusp in the Galactic Center
• Radio/X-Ray Luminosity Relation for X-Ray Bright Galactic Nuclei: Implications on Weighing Supermassive Black Hole
• Low angular momentum flow model of Sgr A* activity
• Effects of wind on radiation spectra from magnetized accretion disks
• Self-similar solutions of viscous and resistive ADAFs with thermal conduction
• Photons from Dark Matter in a (non-Universal) Extra Dimension model
• The XXL Survey. XLI. Radio AGN luminosity functions based on the GMRT $610\mathrm{MHz}$ continuum observations
• High-Resolution Radio Observations of Five Optically Selected Type 2 Quasars
• Selected Chapters on Active Galactic Nuclei as Relativistic Systems
• Shadowing of the Nascent Jet in NGC 4261 by a Line-Emitting Supersonic Accretion Disk
• Radio Variability of the Sagittarius ${\mathrm{A}}^{\ast }$ due to an Orbiting Star
• The Jet in the Galactic Center: An Ideal Laboratory for Magnetohydrodynamics and General Relativity
• Testing the Existence of Event Horizons against Rotating Reflecting Surfaces
• Active Galaxies in the UV
• High Energy Activity of the Super-Massive Black Hole at the Galactic Center
• G2 and Sgr A*: A Cosmic Fizzle At The Galactic Center
• The Collisionless Magnetoviscous-Thermal Instability
• The Galactic Center Black Hole Laboratory
• Signatures of Energetic Protons in Hot Accretion Flows: Synchrotron Cooling of Protons in Strongly Magnetized Pulsars
• Finding LoTSS of hosts for GRBs: a search for galaxy - gamma-ray burst coincidences at low frequencies with LOFAR
• SgrA* emission at 7mm: variability and periodicity
• A New X-Ray Flare from the Galactic Nucleus Detected with the XMM-Newton
• Parabolic-like Trend in SiO Ratios throughout the Central Molecular Zone: Possible Signature of a Past Nuclear Activity in the Galactic Center
• A Hydrodynamical Thermal Irradiated Wind from the Outer Thin Accretion Disk in Low-luminosity Active Galactic Nuclei
• Radiative energy from a reconnection region around massive black hole
• A New Parameter In Accretion Disk Model
• Accelerated protons produced by magnetic Penrose process in Sgr A*
• Explaining the spectrum from the Galactic Centre using a two temperature plasma