X-ray Astronomy and the IR Background

2001 ◽  
Vol 204 ◽  
pp. 335-345
Author(s):  
Richard Mushotzky
Keyword(s):  
Star Formation ◽  
Intergalactic Medium ◽  
Massive Stars ◽  
Active Galaxies ◽  
Infrared Galaxies ◽  
Metal Production ◽  
X Ray ◽  
Luminous Infrared Galaxies ◽  
Early Origin ◽  
X Ray Background

I review the recent Chandra results on the sources of the X-ray background and the X-ray properties of the SCUBA sources. We conclude that 10–20% of the IR background is produced by active galaxies and a similar fraction of the SCUBA sources harbor luminous AGN. Many of the Chandra sources are apparently luminous infrared galaxies themselves, but factors of 2–10 below the SCUBA limits. We summarize the X-ray evidence for metal production in groups and clusters and point out that these data require considerably more star formation than inferred from optical stellar data. The abundance ratios of Fe and Si indicate that much of the metals in groups and clusters was produced by massive stars, and the lack of evolution in Fe out to z ~ 0.5 argues for quite an early origin for the metals. This same process also seems to have injected considerable energy into the gas in groups and clusters, which may have dominated the mechanism of star formation and produced a metal-enriched intergalactic medium

scholarly journals Multiwavelength morphological study of active galaxies

2019 ◽  
Vol 15 (S356) ◽  
pp. 295-298
Author(s):  
Betelehem Bilata-Woldeyes ◽  
Mirjana Pović ◽  
Zeleke Beyoro-Amado ◽  
Tilahun Getachew-Woreta ◽  
Shimeles Terefe
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
Formation Rate ◽  
Stellar Mass ◽  
Active Galaxies ◽  
Morphological Properties ◽  
X Rays ◽  
Host Galaxies ◽  
X Ray ◽  
Public Data

AbstractStudying the morphology of a large sample of active galaxies at different wavelengths and comparing it with active galactic nuclei (AGN) properties, such as black hole mass (MBH) and Eddington ratio (λEdd), can help us in understanding better the connection between AGN and their host galaxies and the role of nuclear activity in galaxy formation and evolution. By using the BAT-SWIFT hard X-ray public data and by extracting those parameters measured for AGN and by using other public catalogues for parameters such as stellar mass (M*), star formation rate (SFR), bolometric luminosity (Lbol), etc., we studied the multiwavelength morphological properties of host galaxies of ultra-hard X-ray detected AGN and their correlation with other AGN properties. We found that ultra hard X-ray detected AGN can be hosted by all morphological types, but in larger fractions (42%) they seem to be hosted by spirals in optical, to be quiet in radio, and to have compact morphologies in X-rays. When comparing morphologies with other galaxy properties, we found that ultra hard X-ray detected AGN follow previously obtained relations. On the SFR vs. stellar mass diagram, we found that although the majority of sources are located below the main sequence (MS) of star formation (SF), still non-negligible number of sources, with diverse morphologies, is located on and/or above the MS, suggesting that AGN feedback might have more complex influence on the SF in galaxies than simply quenching it, as it was suggested in some of previous studies.

scholarly journals Molecules as tracers of galaxy evolution

2012 ◽  
Vol 8 (S292) ◽  
pp. 199-208 ◽  
Author(s):  
Susanne Aalto
Keyword(s):  
Black Holes ◽  
Star Formation ◽  
High Resolution ◽  
Galaxy Evolution ◽  
Large Scale ◽  
Short Review ◽  
Stimulated Emission ◽  
Molecular Gas ◽  
Infrared Galaxies ◽  
Luminous Infrared Galaxies

AbstractStudying the molecular phase of the interstellar medium in galaxies is fundamental for the understanding of the onset and evolution of star formation and the growth of supermassive black holes. We can use molecules as observational tools exploiting them as tracers of chemical, physical and dynamical conditions. In this short review, key molecules (e.g. HCN, HCO+, HNC, HC3N, CN, H3O+) in identifying the nature of buried activity and its evolution are discussed including some standard astrochemical scenarios. Furthermore, we can use IR excited molecular emission to probe the very inner regions of luminous infrared galaxies (LIRGs) allowing us to get past the optically thick dust barrier of the compact obscured nuclei, e.g. in the dusty LIRG NGC4418. High resolution studies are often necessary to separate effects of excitation and radiative transport from those of chemistry - one example is absorption and effects of stimulated emission in the ULIRG Arp220. Finally, molecular gas in large scale galactic outflows is briefly discussed.

scholarly journals Recent Star Formation in Very Luminous Infrared Galaxies

2001 ◽  
pp. 171-176 ◽  
Author(s):  
Alessandro Bressan ◽  
Bianca Poggianti ◽  
Alberto Franceschini
Keyword(s):  
Star Formation ◽  
Infrared Galaxies ◽  
Luminous Infrared Galaxies

Extragalactic X-ray sources and the diffuse X-ray background

1979 ◽  
Vol 366 (1726) ◽  
pp. 391-402 ◽  
Keyword(s):  
Spatial Distribution ◽  
Euclidean Space ◽  
Active Galaxies ◽  
Clusters Of Galaxies ◽  
Optical Identification ◽  
X Ray ◽  
Luminosity Functions ◽  
Sky Survey ◽  
Order Of Magnitude ◽  
X Ray Background

Results from the Ariel 5 sky survey instrument relating to the properties and the spatial distribution of extragalactic X-ray sources are discussed. The lg N -lg S relation for sources in the 2A catalogue is consistent with a uniform distribution of sources in Euclidean space. In addition, measure­ments of fluctuations in the X-ray background suggest that the Euclidean form of the source counts can be extrapolated to flux levels at least an order of magnitude fainter than the 2A catalogue limit. Information is also available from the optical identification of 2A sources which, through redshift measurements, enables the X-ray luminosity functions of the two main classes of source, namely clusters of galaxies and active galaxies, to be determined. The luminosity functions can be used to calculate the contribution of clusters of galaxies and active galaxies to the diffuse X-ray background in the 2-10 keV range. It is found that cosmological evolution of one or both populations is required to account for the diffuse X-ray background entirely in terms of the integrated emission from these sources.

scholarly journals Hot Gas in Groups and Their Galaxies

1998 ◽  
Vol 188 ◽  
pp. 61-64
Author(s):  
Trevor J. Ponman ◽  
Alexis Finoguenov
Keyword(s):  
Star Formation ◽  
Intergalactic Medium ◽  
Heavy Elements ◽  
X Ray ◽  
Hot Gas ◽  
Group Environment ◽  
Velocity Dispersions

It is clear that there is an important interplay between galaxies and the group environment. At the velocity dispersions (~ 100 km s−1) characteristic of groups, the galaxies interact strongly, leading to triggering of star formation, and galaxy merging. We can expect to see evidence of such processes through differences in the properties of galaxies in groups compared to field galaxies. Conversely, the galaxies affect their environment, as is apparent from the presence of heavy elements in the hot intergalactic medium (IGM) in groups, which emit characteristic X-ray lines.

scholarly journals Heating and Ionization of the Intergalactic Medium by an Early X‐Ray Background

2001 ◽  
Vol 563 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Aparna Venkatesan ◽  
Mark L. Giroux ◽  
J. Michael Shull
Keyword(s):  
Intergalactic Medium ◽  
X Ray ◽  
X Ray Background

scholarly journals Luminous IR Galaxies in a Merger Sequence: Bima Co Imaging

1999 ◽  
Vol 186 ◽  
pp. 227-230
Author(s):  
Y. Gao ◽  
R.A. Gruendl ◽  
C.-Y. Hwang ◽  
K.Y. Lo
Keyword(s):  
Star Formation ◽  
Power Output ◽  
Infrared Galaxies ◽  
Physical Processes ◽  
Luminous Infrared Galaxies ◽  
Bolometric Luminosity

The power output in luminous infrared galaxies (LIGs, LIR ≳ 1011L⊙, H0 = 75 kms−1 Mpc−1) can approach the bolometric luminosity of quasars and can be provided by either starbursts or dust-enshouded QSOs, or both. Most LIGs appear to comprise of mergers of gas-rich galaxies. So, intense bursts of star formation apparently result from interaction and merging of galaxies, but the exact physical processes involved in collecting the large amount of gas involved and in initiating the starbursts are not well understood.

scholarly journals 9.18. Galactic winds in active galaxies

1998 ◽  
Vol 184 ◽  
pp. 417-418 ◽  
Author(s):  
S. Veilleux ◽  
J. Bland-Hawthorn ◽  
G. Cecil ◽  
P. Shopbell
Keyword(s):  
Absorption Line ◽  
Galaxy Formation ◽  
Large Scale ◽  
Large Scale Structure ◽  
Active Galaxies ◽  
Large Scale Circulation ◽  
X Ray ◽  
Hubble Sequence ◽  
Galactic Winds ◽  
X Ray Background

The effects of large-scale galactic winds in active galaxies may be far-reaching. It has been suggested that the Hubble sequence can be understood in terms of a galaxy's greater ability to sustain winds with increasing bulge-to-disk ratio. The large-scale circulation of gas associated with these galactic winds might help explain the mass-metallicity relation between galaxies and the metallicity-radius relation within galaxies. Galactic winds probably contribute non-negligibly to the cosmic X-ray background and may be involved in the quasar absorption-line phenomenon. The cosmological implications of the wind phenomenon have been widely explored in the context of proto-galaxies and quasars. The extremely energetic galactic winds that were likely associated with galaxy formation almost certainly played a key role in heating and ionizing the intergalactic medium at high redshifts and may have created the seeds for the large-scale structure we see today.

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