相关论文: A simple model of radiative emission in M87

We aim to determine the properties of the central region of NGC 1052 using X-ray and radio data. NGC 1052 (z=0.005) has been investigated for decades in different energy bands and shows radio lobes and a low luminosity active galactic…

Recent XMM-Newton observations of the cooling flow gas in M87 indicate sharply decreasing oxygen, iron and silicon abundances within $\sim 5$ kpc of the galactic center. This result is unexpected since stellar mass loss and Type Ia…

Observations of the hot gas surrounding Sgr A* and a few other nearby galactic nuclei imply electron and proton mean free paths comparable to the gas capture radius: hot accretion likely proceeds under weakly-collisional conditions in these…

We use the observational data in radio, optical and X-ray wavebands, for a sample of active galactic nuclei (AGNs) with measured black hole masses, to explore the origin of radio emission from nearby low-luminosity active galactic nuclei…

We propose that the X--ray emission from radio quiet AGN and galactic black holes is due to Comptonization of soft thermal photons emitted by the underlying accretion disk in localized structures (blobs). The power per unit area produced by…

We study the energetics of the accretion-induced outflow and then plausible jet around black holes/compact objects using a newly developed disc-outflow coupled model. Inter-connecting dynamics of outflow and accretion essentially upholds…

Low-luminosity active galactic nuclei (LLAGNs) represent the bulk of the AGN population in the present-day universe and they trace the low-level accreting supermassive black holes. In order to probe the accretion and jet physical properties…

The recent Chandra X-ray observations of the nucleus of M31, combined with earlier VLA radio and HST UV spectral measurements, provide the strictest constraints on the nature of accretion onto the supermassive black hole (called M31*…

An important parameter in the theory of hot accretion flows around black holes is $\delta$, which describes the fraction of ``viscously'' dissipated energy in the accretion flow that goes directly into heating electrons. For a given mass…

It has been found that a class of optically-thin two-temperature advection-dominated accretion solutions explains many observations of low-luminosity accreting black holes. Here it is shown that these models give a satisfactory description…

The standard Advection-Dominated Accretion Flow (ADAF) is studied using a set of self-similar analytical solutions in the spherical coordinates. Our new solutions are useful for studying ADAFs without dealing with the usual mathematical…

Studying accretion phenomena is a window into understanding most heavenly bodies, from the birth of stars to Active galactic nuclei(AGN). We would adopt the effect of the radiation pressure which reduces accretion rates M on the accretion…

Observations of the Seyfert 2 and starburst galaxy NGC 5135 with the Chandra X-ray Observatory demonstrate that both of these phenomena contribute significantly to its X-ray emission. We spatially isolate the active galactic nucleus (AGN)…

Observations of active galactic nuclei have revealed a correlation between millimeter luminosity, X-ray luminosity, and mass, suggesting the emission in each of these bands is powered by a common source. Starting with a set of five general…

The mass of the central black hole in the active galaxy NGC 4258 (M106) has been measured to be $M=3.6\times10^7\Msun$ (Miyoshi et al. 1995). The Eddington luminosity corresponding to this mass is $L_E=4.5\times10^{45}$ erg s$^{-1}$. By…

The LINER nucleus of the nearby spiral galaxy M81 was pointed by BeppoSAX, which caught it at the highest (2-10) keV flux level observed so far. The LECS, MECS and PDS data, extending over (0.1-100) keV, are used to investigate the physical…

We report here on a calculation of thermalization time-scale of the two temperature advection dominated accretion flow (ADAF) model. It is established that time required to equalize the electron and ion temperatures via electron-ion…

It is currently believed that the ``standard'' accretion disk theory under-predicts the observed X-ray luminosity from Soft X-ray Transients (SXT) in quiescence by as much as 4 to 6 orders of magnitude. This failure of the standard model is…

We study the contribution of thermal and non-thermal processes to the inverse Compton emission of the radio galaxy M 87 by modelling its broad-band emission. Through this we aim to derive insight into where within the AGN the X-ray,…

We estimate the masses of massive black holes in BL Lac objects from their host galaxy luminosity. The power of jets and central optical ionizing luminosity for a sample of BL Lac objects are derived from their extended radio emission and…