scholarly journals A two-zone emission model for Blazars and the role of Accretion Disk MHD winds

2021 ◽  
Author(s):  
Stella Boula ◽  
Apostolos Mastichiadis ◽  
Demosthenes Kazanas
2019 ◽  
Vol 626 ◽  
pp. A115 ◽  
Author(s):  
G. Marcel ◽  
J. Ferreira ◽  
M. Clavel ◽  
P.-O. Petrucci ◽  
J. Malzac ◽  
...  

Context. Transient X-ray binaries (XrB) exhibit very different spectral shapes during their evolution. In luminosity-color diagrams, their behavior in X-rays forms q-shaped cycles that remain unexplained. In Paper I, we proposed a framework where the innermost regions of the accretion disk evolve as a response to variations imposed in the outer regions. These variations lead not only to modifications of the inner disk accretion rate ṁin, but also to the evolution of the transition radius rJ between two disk regions. The outermost region is a standard accretion disk (SAD), whereas the innermost region is a jet-emitting disk (JED) where all the disk angular momentum is carried away vertically by two self-confined jets. Aims. In the previous papers of this series, it has been shown that such a JED–SAD disk configuration could reproduce the typical spectral (radio and X-rays) properties of the five canonical XrB states. The aim of this paper is now to replicate all X-ray spectra and radio emission observed during the 2010–2011 outburst of the archetypal object GX 339-4. Methods. We used the two-temperature plasma code presented in two previous papers (Papers II and III) and designed an automatic ad hoc fitting procedure that for any given date calculates the required disk parameters (ṁin,rJ) that fit the observed X-ray spectrum best. We used X-ray data in the 3–40 keV (RXTE/PCA) spread over 438 days of the outburst, together with 35 radio observations at 9 GHz (ATCA) dispersed within the same cycle. Results. We obtain the time distributions of ṁin(t) and rJ(t) that uniquely reproduce the X-ray luminosity and the spectral shape of the whole cycle. In the classical self-absorbed jet synchrotron emission model, the JED–SAD configuration also reproduces the radio properties very satisfactorily, in particular, the switch-off and -on events and the radio-X-ray correlation. Although the model is simplistic and some parts of the evolution still need to be refined, this is to our knowledge the first time that an outburst cycle is reproduced with such a high level of detail. Conclusions. Within the JED–SAD framework, radio and X-rays are so intimately linked that radio emission can be used to constrain the underlying disk configuration, in particular, during faint hard states. If this result is confirmed using other outbursts from GX 339-4 or other X-ray binaries, then radio could be indeed used as another means to indirectly probe disk physics.


2005 ◽  
Vol 635 (2) ◽  
pp. 1203-1216 ◽  
Author(s):  
Sera Markoff ◽  
Michael A. Nowak ◽  
Jorn Wilms
Keyword(s):  

2000 ◽  
Vol 537 (1) ◽  
pp. 236-244 ◽  
Author(s):  
Feng Yuan ◽  
Qiuhe Peng ◽  
Ju‐fu Lu ◽  
Jianmin Wang

1995 ◽  
Vol 10 ◽  
pp. 597-598
Author(s):  
R. Wehrse

An accretion disk is formed when matter with angular momentum is flowing on a gravitating object (as e.g. a white dwarf, a neutron star, a young stellar object, or a black bole). It radiates because the transport of angular momentum (required for the matter to reach the central object) necessarily implies the conversion of potential energy into a form of energy that corresponds to higher entropy. Many aspects of the physics (as e.g. the mechanism for the heat generation) are not yet well understood but they are presently one of the centers of astronomical interest (see e.g. the books by Frank, King, and Raine, 1992, or by Wheeler, 1993).


Pramana ◽  
1991 ◽  
Vol 36 (5) ◽  
pp. 445-488 ◽  
Author(s):  
A R Prasanna

1984 ◽  
Vol 75 ◽  
pp. 691
Author(s):  
A.F. Cook ◽  
F.A. Franklin ◽  
E.M. Shoemaker ◽  
R.J. Terrile

Shoemaker and Terrile have shown that several small satellites can be the parents of Saturn's rings and have suggested these as the origin of the broad systematic differences in the photometric properties of the rings. Dramatic variations on the smallest scales appear in the images obtained from Voyager. The variations of the surface of Enceladus suggest the importance of differentiation of satellites heated by tidal action maintained by resonances, as pointed out by C.M. Yoder. Subsequent break-up of such satellites, either under a large impact or under increasing tidal action of Saturn as its mass increased, would have yielded a mixture of different crustal and interior materials with different spectra of sizes and masses. We shall discuss the possible role of radial differentiation of particles in terms of their masses initiated by the combined activity of instabilities discussed long ago by Maxwell and by Cook and Franklin with those proposed recently by Ward and by Lin and Bodenheimer. In this way, we may reach an explanation of variations on the smallest scales. Comparison will be made with the expected behaviour of a primary accretion disk composed of a uniform distribution of material.


2013 ◽  
Vol 777 (2) ◽  
pp. 164 ◽  
Author(s):  
R. E. Mason ◽  
C. Ramos Almeida ◽  
N. A. Levenson ◽  
R. Nemmen ◽  
A. Alonso-Herrero

Sign in / Sign up

Export Citation Format

Share Document