Results 41 to 50 of about 200 (175)

Star formation in southern Seyfert galaxies [PDF]

Monthly Notices of the Royal Astronomical Society, 1998
We have produced radio maps, using the Australia Telescope Compact Array, of the central regions of six southern type 2 Seyfert galaxies (NGC 1365, 4945, 6221, 6810, 7582 and Circinus) with circumnuclear star formation, to estimate the relative contribution of star formation activity compared to activity from the active galactic nucleus (AGN).
Forbes, Duncan, Norris, R. P.
openaire   +5 more sources

Das zirkumgalaktische Medium

Physik in unserer Zeit, Volume 56, Issue 1, Page 30-37, January 2025.
Galaxien wie die Milchstraße sind umhüllt von einem gigantischen Kokon aus diffusem Gas. Aktuelle Forschungsergebnisse belegen, dass dieses zirkumgalakische Medium eine entscheidende Rolle für die Entstehung und Entwicklung von Galaxien spielt. Zusammenfassung Als zirkumgalaktisches Medium bezeichnet man die gasförmigen Hüllen von Galaxien, die sich ...
Philipp Richter
wiley   +1 more source

Recoiling Black Holes: Electromagnetic Signatures, Candidates, and Astrophysical Implications

Advances in Astronomy, Volume 2012, Issue 1, 2012., 2012
Supermassive black holes (SMBHs) may not always reside right at the centers of their host galaxies. This is a prediction of numerical relativity simulations, which imply that the newly formed single SMBH, after binary coalescence in a galaxy merger, can receive kick velocities up to several 1000 km/s due to anisotropic emission of gravitational waves ...
S. Komossa, Francesca Civano
wiley   +1 more source

Probing extreme black‐hole outflows on short timescales via high spectral‐resolution x‐ray imagers

Astronomische Nachrichten, Volume 345, Issue 6-7, July-August 2024.
Abstract We investigate outflows and the physics of super‐Eddington versus sub‐Eddington regimes in black hole systems. Our focus is on prospective science using next‐generation high‐resolution soft x‐ray instruments. We highlight the properties of black hole ultraluminous x‐ray source (ULX) systems in particular. Owing to scale invariance in accreting
C. Pinto, J. F. Steiner, A. Bodaghee, P. Chakraborty, M. Sobolewska, D. R. Pasham, A. Ogorzalek, J. Zuhone, A. Bogdan, M. Vogelsberger   +9 more
wiley   +1 more source

The Cosmic History of Black Hole Growth from Deep Multiwavelength Surveys

Advances in Astronomy, Volume 2012, Issue 1, 2012., 2012
Significant progress has been made in the last few years on understanding how supermassive black holes form and grow. In this paper, we begin by reviewing the spectral signatures of active galactic nuclei (AGN) ranging from radio to hard X‐ray wavelengths.
Ezequiel Treister, C. Megan Urry, Francesca Civano   +2 more
wiley   +1 more source

IRAS observations of active galaxies

, 1985
The IRAS survey gives an unbiased view of the infrared properties of the active galaxies. Seyfert galaxies occupy much the same area in color-color plots as to normal infrared bright galaxies, but extend the range towards flatter 60 to 25 mm slopes ...
G. Neugebauer, Rowan-Robinson, M., Neugebauer, G., Soifer, B. T., B. T. Soifer, M. Rowan-Robinson   +5 more
core   +2 more sources

AGN Obscuration and the Unified Model

Advances in Astronomy, Volume 2012, Issue 1, 2012., 2012
Unification Models of Active Galactic Nuclei postulate that all the observed differences between type 1 and type 2 objects are due to orientation effects with respect to the line of sight to the observer. The key ingredient of these models is the obscuring medium, historically envisaged as a toroidal structure on a parsec scale.
Stefano Bianchi, Roberto Maiolino, Guido Risaliti, Isabelle Gavignaud   +3 more
wiley   +1 more source

Unveiling the physics behind the spectral variations of changing-look quasars with optical polarimetry

, 2017
International audienceA handful of active galactic nuclei (AGN) have shown strong spectral variations in the optical band between epochs that are years apart.
Marin, F., F. Marin
core   +1 more source

A Practical Guide to the Massive Black Hole Cosmic History

Advances in Astronomy, Volume 2012, Issue 1, 2012., 2012
I review our current understanding of massive black hole (MBH) formation and evolution along the cosmic history. After a brief introductory overview of the relevance of MBHs in the hierarchical structure formation paradigm, I discuss the main viable channels for seed BH formation at high redshift and for their subsequent mass growth and spin evolution.
A. Sesana, Francesco Shankar
wiley   +1 more source

Testing warm Comptonization models for the origin of the soft X-ray excess in AGNs [PDF]

, 2018
International audienceThe X-ray spectra of many active galactic nuclei (AGNs) show a soft X-ray excess below 1–2 keV on top of the extrapolated high-energy power law. The origin of this component is uncertain.
BIANCHI, STEFANO, Petrucci, P.O., Ursini, F., De Rosa, A., Petrucci, P. -O., G. Matt, Cappi, M., Matt, G., CAPPI, MASSIMO, P.-O. Petrucci, J. Malzac, Malzac, J., A. De Rosa, M. Dadina, S. Bianchi, Ursini, Francesco, F. Ursini, DE ROSA, ALESSANDRA, Petrucci, Pierre-Olivier, DADINA, MAURO, Bianchi, S., Dadina, M., M. Cappi   +22 more
core   +1 more source