scholarly journals The impact of Faraday effects on polarized black hole images of Sagittarius A*

2018 ◽  
Vol 478 (2) ◽  
pp. 1875-1883 ◽  
Author(s):  
Alejandra Jiménez-Rosales ◽  
Jason Dexter
2019 ◽  
Vol 15 (S356) ◽  
pp. 143-143
Author(s):  
Jaya Maithil ◽  
Michael S. Brotherton ◽  
Bin Luo ◽  
Ohad Shemmer ◽  
Sarah C. Gallagher ◽  
...  

AbstractActive Galactic Nuclei (AGN) exhibit multi-wavelength properties that are representative of the underlying physical processes taking place in the vicinity of the accreting supermassive black hole. The black hole mass and the accretion rate are fundamental for understanding the growth of black holes, their evolution, and the impact on the host galaxies. Recent results on reverberation-mapped AGNs show that the highest accretion rate objects have systematic shorter time-lags. These super-Eddington accreting massive black holes (SEAMBHs) show BLR size 3-8 times smaller than predicted by the Radius-Luminosity (R-L) relationship. Hence, the single-epoch virial black hole mass estimates of highly accreting AGNs have an overestimation of a factor of 3-8 times. SEAMBHs likely have a slim accretion disk rather than a thin disk that is diagnostic in X-ray. I will present the extreme X-ray properties of a sample of dozen of SEAMBHs. They indeed have a steep hard X-ray photon index, Γ, and demonstrate a steeper power-law slope, ασx.


2020 ◽  
Vol 35 (28) ◽  
pp. 2050177
Author(s):  
Shubham Kala ◽  
Saurabh ◽  
Hemwati Nandan ◽  
Prateek Sharma

Gravitational lensing and black hole shadows are one of the strongest observational evidences to prove the existence of black holes in the universe. The gravitational lensing arises due to the deflection of light by the gravitational field of a gravitating body such as a black hole. Investigation of the shadow cast by a compact object as well as deflection of light around it may provide the useful information about physical nature of the particular compact object and other related aspects. In this paper, we study the deflection of light by a dual-charged stringy black hole space–time derived in dilaton-Maxwell gravity. The variation of deflection angle with the impact parameter for different values of electric and magnetic charges is studied. We also study the shadow of this black hole space–time to obtain the radius of shadow cast by it. We have considered an optically thin emission disk around it and observed that there are not significant changes in the shadow cast by this black hole compared to well-known Schwarzschild black hole space–time in GR.


2019 ◽  
Vol 15 (S350) ◽  
pp. 274-277
Author(s):  
Junjie Mao

AbstractPhotoionized outflows in active galactic nuclei (AGNs) are thought to influence their circumnuclear and host galactic environment. However, the distance of the outflow with respect to the black hole is poorly constrained, which limits our understanding of the kinetic power by the outflow. Therefore, the impact of AGN outflows on their host galaxies is uncertain. If the density of the outflow is known, its distance can be derived. Density measurement via variability studies and density sensitive lines have been used, albeit not very effective in the X-ray band. Good measurements are rather demanding or challenging for the current generation of (grating) spectrometers. The next generation of spectrometers will certainly provide data with better quality and large quantity, leading to tight constraints on the location and the kinetic power of AGN outflows. This contribution summarizes the state-of-the-art in this field.


2019 ◽  
Vol 122 (11) ◽  
Author(s):  
Alexander C. Jenkins ◽  
Richard O‘Shaughnessy ◽  
Mairi Sakellariadou ◽  
Daniel Wysocki

2019 ◽  
Vol 491 (4) ◽  
pp. 5793-5793
Author(s):  
Jongsuk Hong ◽  
Enrico Vesperini ◽  
Abbas Askar ◽  
Mirek Giersz ◽  
Magdalena Szkudlarek ◽  
...  

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