scholarly journals Early Evolution of Galaxies: Preliminary Results

1977 ◽  
Vol 45 ◽  
pp. 115-118
Author(s):  
J. P. Chiezel ◽  
B. Lazareff ◽  
Laurent Vigroux
Keyword(s):  
Emission Line ◽  
Radial Flow ◽  
Galactic Center ◽  
Elliptical Galaxies ◽  
Progress Report ◽  
Early Evolution ◽  
Clusters Of Galaxies ◽  
X Ray ◽  
Evolution Of Galaxies ◽  
Preliminary Version

This paper is a progress report on studies of coupled dynamical and chemical evolution of galaxies. We have focused our attention on the occurence of galactic hot winds. Such hot winds have been studied by Mathews and Baker (1971) for elliptical galaxies. Recently the detection of an iron X-ray emission line in clusters of galaxies give some support to their existence (Vigroux, 1977). On an other hand, the large radial flow in the galactic center might be explained by such hot wind. We shall present here a preliminary version of our evolution model and the results obtained for the early evolution of a 1.2 × 1012Mʘgalaxy.

scholarly journals X-Ray Surveys as Tools to Investigate the Cosmological Evolution of Quasars, BL Lac Objects and Clusters of Galaxies

1987 ◽  
Vol 124 ◽  
pp. 593-595
Author(s):  
Isabella M. Gioia ◽  
Tommaso Maccacaro ◽  
Anna Wolter
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Progress Report ◽  
Cosmological Evolution ◽  
Clusters Of Galaxies ◽  
Bl Lac Objects ◽  
X Ray ◽  
Basic Properties ◽  
Bl Lac ◽  
Einstein Observatory

We present a progress report on a major extension of the Einstein Observatory Medium Sensitivity Survey (MSS). The basic properties of the extragalactic sources identified with Active Galactic Nuclei (AGN) and clusters of galaxies are discussed. Results from previous work are briefly summarized.

scholarly journals The Fate of Intra-Group Medium

1998 ◽  
Vol 188 ◽  
pp. 310-311
Author(s):  
Yuhri Ishimaru
Keyword(s):  
Elliptical Galaxies ◽  
Clusters Of Galaxies ◽  
X Ray ◽  
Hydrodynamical Simulations

Combining X-ray data for clusters of galaxies, groups, and elliptical galaxies, we have obtained the evidence for that groups eject parts of the intra-group medium (IGM) via supernovae-driven ‘group winds’ like ellipticals. This scenario is confirmed by 1D hydrodynamical simulations.

scholarly journals Cooling Flows and the Formation of Dark matter

1987 ◽  
Vol 117 ◽  
pp. 201-213 ◽  
Author(s):  
A. C. Fabian ◽  
K. A. Arnaud ◽  
P. A. Thomas
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Elliptical Galaxies ◽  
High Mass ◽  
Clusters Of Galaxies ◽  
Local Models ◽  
X Ray ◽  
Cooling Flows ◽  
Mass Profiles

The distribution of matter condensing out of cooling flows in clusters of galaxies and individual elliptical galaxies has been studied using X-ray data and is found to resemble the expected mass profiles of the underlying galaxies. Most of the cooled gas must create objects of high mass-to-light ratio, although some more normal stars are produced. Cooling flows provide an observable mechanism for the continual formation of dark matter around galaxies. Since the conditions at galaxy formation are similar to those in cooling flows if the gas reaches the virial temperature, we suggest that they are local models of galaxy formation.

scholarly journals New emission line at ~3.5 keV - observational status, connection with radiatively decaying dark matter and directions for future studies

2014 ◽  
Vol 4 (1-2) ◽  
pp. 9-14 ◽  
Author(s):  
D. Iakubovskyi
Keyword(s):  
Dark Matter ◽  
Emission Line ◽  
Particle Physics ◽  
Clusters Of Galaxies ◽  
Future Directions ◽  
Future Studies ◽  
X Ray ◽  
Andromeda Galaxy ◽  
Decaying Dark Matter ◽  
Observational Status

Recent works of Bulbul et al. (2014) and Boyarsky et al. (2014), claiming the detection of the extra emission line with energy ∼3.5 keV in X-ray spectra of certain clusters of galaxies and nearby Andromeda galaxy, have raised a considerable interest in astrophysics and particle physics communities. A number of new observational studies claim detection or non-detection of the extra line in X-ray spectra of various cosmic objects. In this review I summarise existing results of these studies, overview possible interpretations of the extra line, including intriguing connection with radiatively decaying dark matter, and show future directions achievable with existing and planned X-ray cosmic missions.

scholarly journals An X-ray survey of the central molecular zone: variability of the FeKα emission line

2013 ◽  
Vol 9 (S303) ◽  
pp. 94-96
Author(s):  
Simona Soldi ◽  
Maïca Clavel ◽  
Andrea Goldwurm ◽  
Mark R. Morris ◽  
Gabriele Ponti ◽  
...  
Keyword(s):  
Emission Line ◽  
Molecular Clouds ◽  
Galactic Center ◽  
X Ray ◽  
Preliminary Results ◽  
Sgr A ◽  
Flux Increase ◽  
C Complex ◽  
First Time

AbstractThe bulk of the FeKα emission detected in the central molecular zone (CMZ) is thought to be associated with reflection by the central molecular clouds of enhanced past emission from an external X-ray source, most likely Sgr A*. In order to follow the propagation of the reflected emission through the Galactic center (GC), we analyzed all XMM-Newton observations carried out from 2000 to 2012. Preliminary results indicate that while most of the regions that were bright at 6.4 keV in 2000–2001 have a significantly lower flux in 2012, a few other experienced a flux increase. We report for the first time a significant decrease of the FeKα emission in the Sgr C complex, supporting the reflection origin of the 6.4 keV emission detected in this region.

scholarly journals The 3 Ms Chandra campaign on Sgr A*: a census of X-ray flaring activity from the Galactic center

2013 ◽  
Vol 9 (S303) ◽  
pp. 374-378
Author(s):  
J. Neilsen ◽  
M. A. Nowak ◽  
C. Gammie ◽  
J. Dexter ◽  
S. Markoff ◽  
...  
Keyword(s):  
Black Hole ◽  
Spectral Resolution ◽  
Galactic Center ◽  
Progress Report ◽  
Deep Sleep ◽  
X Ray ◽  
Supermassive Black Hole ◽  
Black Hole Accretion ◽  
Sgr A ◽  
Hole Accretion

AbstractOver the last decade, X-ray observations of Sgr A* have revealed a black hole in a deep sleep, punctuated roughly once per day by brief flares. The extreme X-ray faintness of this supermassive black hole has been a long-standing puzzle in black hole accretion. To study the accretion processes in the Galactic center, Chandra (in concert with numerous ground- and space-based observatories) undertook a 3 Ms campaign on Sgr A* in 2012. With its excellent observing cadence, sensitivity, and spectral resolution, this Chandra X-ray Visionary Project (XVP) provides an unprecedented opportunity to study the behavior of the closest supermassive black hole. We present a progress report from our ongoing study of X-ray flares, including the brightest flare ever seen from Sgr A*. Focusing on the statistics of the flares and the quiescent emission, we discuss the physical implications of X-ray variability in the Galactic center.

New results in searching for axions by astronomical methods

2016 ◽  
Vol 31 (02n03) ◽  
pp. 1641019 ◽  
Author(s):  
Yu. N. Gnedin ◽  
M. Yu. Piotrovich
Keyword(s):  
Emission Line ◽  
Linear Polarization ◽  
Radiative Decay ◽  
Background Radiation ◽  
Polarization State ◽  
Transformation Process ◽  
Clusters Of Galaxies ◽  
X Ray ◽  
Goldstone Bosons ◽  
Axion Decay

We discuss the astronomical methods of searching for light Goldstone bosons (axions and arions). The basic idea is to use processes of coupling between axions and photons: a) the axion decay into two photons; b) the transformation process of photons into axions (arions) in the magnetic fields of stars and also of interstellar and intergalactic media; c) the inverse process of transformations of axions (arions) which are generated into cores of stars into X-ray photons. The decaying axions affect upon the diffuse extragalactic background radiation, the brightness of the night sky and especially on the intergalactic light of clusters of galaxies due to generation of the axion radiative decay emission line. The processes (b) and (c) are strongly dependent on polarization state of photon and may produce a noticeable amount of linear polarization.

White-Light Coronal Structures: Streamers and CMEs

1994 ◽  
Vol 144 ◽  
pp. 82
Author(s):  
E. Hildner
Keyword(s):  
Emission Line ◽  
Electron Density ◽  
White Light ◽  
Coronal Mass Ejections ◽  
X Rays ◽  
Solar Cycles ◽  
Temperature Function ◽  
X Ray ◽  
Eclipse Observations ◽  
Coronal Structures

AbstractOver the last twenty years, orbiting coronagraphs have vastly increased the amount of observational material for the whitelight corona. Spanning almost two solar cycles, and augmented by ground-based K-coronameter, emission-line, and eclipse observations, these data allow us to assess,inter alia: the typical and atypical behavior of the corona; how the corona evolves on time scales from minutes to a decade; and (in some respects) the relation between photospheric, coronal, and interplanetary features. This talk will review recent results on these three topics. A remark or two will attempt to relate the whitelight corona between 1.5 and 6 R⊙to the corona seen at lower altitudes in soft X-rays (e.g., with Yohkoh). The whitelight emission depends only on integrated electron density independent of temperature, whereas the soft X-ray emission depends upon the integral of electron density squared times a temperature function. The properties of coronal mass ejections (CMEs) will be reviewed briefly and their relationships to other solar and interplanetary phenomena will be noted.

scholarly journals A Systematic X‐Ray Search for Clusters of Galaxies behind the Milky Way. II. The Second CIZA Subsample

2007 ◽  
Vol 662 (1) ◽  
pp. 224-235 ◽  
Author(s):  
Dale D. Kocevski ◽  
Harald Ebeling ◽  
Chris R. Mullis ◽  
R. Brent Tully
Keyword(s):  
Milky Way ◽  
Clusters Of Galaxies ◽  
X Ray

scholarly journals On the relation between mini-halos and AGN feedback in clusters of galaxies

2020 ◽  
Vol 499 (2) ◽  
pp. 2934-2958
Author(s):  
A Richard-Laferrière ◽  
J Hlavacek-Larrondo ◽  
R S Nemmen ◽  
C L Rhea ◽  
G B Taylor ◽  
...  
Keyword(s):  
Large Scale ◽  
State Of The Art ◽  
Vital Role ◽  
Clusters Of Galaxies ◽  
Relativistic Jets ◽  
X Ray ◽  
Core Cluster ◽  
Central Galaxy ◽  
Central Regions ◽  
Radio Power

ABSTRACT A variety of large-scale diffuse radio structures have been identified in many clusters with the advent of new state-of-the-art facilities in radio astronomy. Among these diffuse radio structures, radio mini-halos are found in the central regions of cool core clusters. Their origin is still unknown and they are challenging to discover; less than 30 have been published to date. Based on new VLA observations, we confirmed the mini-halo in the massive strong cool core cluster PKS 0745−191 (z = 0.1028) and discovered one in the massive cool core cluster MACS J1447.4+0827 (z = 0.3755). Furthermore, using a detailed analysis of all known mini-halos, we explore the relation between mini-halos and active galactic nucleus (AGN) feedback processes from the central galaxy. We find evidence of strong, previously unknown correlations between mini-halo radio power and X-ray cavity power, and between mini-halo and the central galaxy radio power related to the relativistic jets when spectrally decomposing the AGN radio emission into a component for past outbursts and one for ongoing accretion. Overall, our study indicates that mini-halos are directly connected to the central AGN in clusters, following previous suppositions. We hypothesize that AGN feedback may be one of the dominant mechanisms giving rise to mini-halos by injecting energy into the intra-cluster medium and reaccelerating an old population of particles, while sloshing motion may drive the overall shape of mini-halos inside cold fronts. AGN feedback may therefore not only play a vital role in offsetting cooling in cool core clusters, but may also play a fundamental role in re-energizing non-thermal particles in clusters.

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