Results 11 to 20 of about 1,397 (183)

SUPERMASSIVE SEEDS FOR SUPERMASSIVE BLACK HOLES [PDF]

The Astrophysical Journal, 2013
9 pages, 2 figures; accepted for publication in ...
Johnson, Jarrett L., Whalen, Daniel J., Li, Hui, Holz, Daniel E.   +3 more
openaire   +2 more sources

Decomposition of the central structure of NGC 2273 in the NIR: A case study

Astronomische Nachrichten, Volume 344, Issue 10, December 2023., 2023
Abstract The Seyfert 2 galaxy NGC 2273 is a prime target to explore how active nuclei can be fed. It has a star‐forming innermost nuclear ring with a radius of 0.33kpc from where material may be funneled to the supermassive black hole in its center. In this article, we discuss high‐resolution adaptive optics aided JHKs images of NGC 2273 taken with the
L. Schey, J. Heidt, A. Pramskiy, D. Thompson, G. Agapito, S. Esposito, R. Gredel, D. Miller, E. Pinna, A. Puglisi, F. Rossi, W. Seifert, G. Taylor, A. Quirrenbach   +13 more
wiley   +1 more source

The potsdam arrayed waveguide spectrograph: A demonstrator of a cross‐dispersed integrated photonic spectrograph developed for the astronomical H‐band

Astronomische Nachrichten, Volume 344, Issue 8-9, October-November 2023., 2023
The Potsdam Arrayed Waveguide Spectrograph (PAWS) is based on an integrated photonic spectrograph designed and developed by innoFSPEC to work in the astronomical H‐band. PAWS demonstrates how a traditional bulk optics spectrograph can be miniaturized and additionally serves as a tool for testing in‐house developed astrophotonical devices.
Eloy Hernandez, Alan Günther, Andreas Stoll, Svend‐Marian Bauer, Stella Vješnica, Kalaga Madhav, Martin M. Roth   +6 more
wiley   +1 more source

PAWS and POCO: NIR Astrophotonic Instruments for Astronomy

Astronomische Nachrichten, Volume 344, Issue 8-9, October-November 2023., 2023
Abstract For near‐infrared ground and space‐based astronomy, compact photonic devices can replace the large bulk optical components in spectrographs, frequency combs, beam combiners, and sky subtraction filters, thus saving cost, reducing volume, weight, and power requirements.
Kalaga Madhav, Alan Günther, Eloy Hernandez, Stella Vjes̆nica, Daniel Bodenmüller, Andreas Stoll, Christer Sandin, Haydar Altuğ Yıldırım, Martin M. Roth   +8 more
wiley   +1 more source

Characterization of a C‐RED One camera for astrophotonical applications

Astronomische Nachrichten, Volume 344, Issue 8-9, October-November 2023., 2023
Abstract To better understand the impact of the avalanche gain applied in the detector technology and apply this technology in our in‐house astrophotonic projects, we have characterized a C‐RED One camera and produced a stable and reliable method for calculating the system gain at any desired avalanche gain setting.
Stella Vješnica, Eloy Hernandez, Kalaga Madhav, Martin M. Roth   +3 more
wiley   +1 more source

Supermassive black holes

Physics World, 2002
After a brief historical introduction, we summarize current efforts and accomplishments in the study of supermassive black holes.
Ferrarese, Laura, Merritt, David
openaire   +2 more sources

Perturbative Solution of the Einstein Constraints with Spin and Momentum Far Away From a Binary Source in the Bowen‐York Formalism

Fortschritte der Physik, Volume 71, Issue 8-9, September 2023., 2023
Abstract The momentum and Hamiltonian constraints of vacuum Einstein equations, within the Bowen‐York formalism, for two interacting black holes in close separation, with anti‐parallel spins and anti‐parallel linear momenta is studied. An analytical solution using perturbation theory is given.
Emel Altas, Emine Ertugrul, Bayram Tekin
wiley   +1 more source

A tool to understand emission mechanisms of blazars through their high‐energy gamma‐ray emission

Astronomische Nachrichten, Volume 344, Issue 6, August 2023., 2023
The blazar SED is characterized by two energy components. Evidence suggests that the low‐energy component is generated by the synchrotron mechanism, but for the high‐energy component, the mechanism is still uncertain. Two main models have been proposed to explain this emission. According to the leptonic model, a correlation between the emission of both
Mabel Osorio, Erick Rangel, José Rodrigo Sacahui, María Magdalena González   +3 more
wiley   +1 more source

Supermassive Black Holes [PDF]

Journal of High Energy Physics, Gravitation and Cosmology, 2019
In the following black hole model, electrons and positrons form a neutral gas which is confined by gravitation. The smaller masses are supported against gravity by electron degeneracy pressure. Larger masses are supported by ideal gas and radiation pressure. In each case, the gas is a polytrope which satisfies the Lane-Emden equation.
openaire   +2 more sources

Unraveling the enigmatic soft x‐ray excess: Current understanding and future perspectives

Astronomische Nachrichten, Volume 344, Issue 6, August 2023., 2023
Abstract This article explores various theoretical models proposed to explain the soft x‐ray excess phenomenon, including warm Comptonization, ionized reflection models, and ionized outflowing disc winds. The soft x‐ray excess is better understood thanks to crucial observations made by ROSAT, XMM‐Newton, and eROSITA.
Thomas Boller
wiley   +1 more source