scholarly journals Discovery of new bright ULIRGs from the IRAS PSC/FSC Combined Catalogue

2018 ◽  
Vol 2 (1) ◽  
pp. 13-20
Author(s):  
G. A. Mikayelyan ◽  
◽  
A. M. Mickaelian ◽  
H. V. Abrahamyan ◽  
G. M. Paronyan ◽  
...  
Keyword(s):  
Star Formation ◽  
Early Universe ◽  
Formation Processes ◽  
Direct Impact ◽  
High Luminosity ◽  
Nuclear Activity ◽  
Active Star ◽  
Multiple Structure ◽  
Activity Types ◽  
Very High

High-luminosity IR galaxies (LIRGs, ULIRGs, and HLIRGs) are important for studies related to star-formation processes in the early Universe, as their luminosity allows to detect them at large distances. High IR indicates active star-formation and often starburst processes, which is typical to HII (starburst, SB) and AGN. An interesting question is whether the starburst triggers AGN or vice versa or there is no direct impact. Considering that very often such objects manifest double and multiple structure, it is also interesting to investigate the interrelationship between the SB, nuclear activity and interactions or merging. We have analyzed the IRAS PSC/FSC Combined Catalogue for search for new bright ULIRGs. By means of the SDSS DR14 data, namely redshifts for those objects having spectroscopy, we have calculated the IR luminosities and have found 114 very high-luminosity IR galaxies; 107 ULIRGs and 7 HLIRGs. Among them, 48 new ULIRGs and 7 new HLIRGs have been discovered. These objects have been studied by SDSS color-color, luminosity-redshift and other diagrams. Further studies will include the content of the sample for activity types and other available data.

scholarly journals Sub-Millimeter Spectral Line Observations in Very Dense Regions

1987 ◽  
Vol 115 ◽  
pp. 173-173
Author(s):  
Neal J. Evans ◽  
Lee G. Mundy ◽  
John H. Davis ◽  
Paul Vanden Bout
Keyword(s):  
Star Formation ◽  
Spectral Line ◽  
Millimeter Wave ◽  
Volume Density ◽  
High Density ◽  
Active Star ◽  
Millimeter Wavelengths ◽  
Active Star Formation ◽  
Very High

In a search for very high density (n ≳ 107 cm−3) regions, the Millimeter Wave Observatory 5-m telescope was used to observe several submillimeter lines. The regions studied were Orion A, M17, S140, and NGC2024. The lines were CS(J=7-6), H2CO(JK-1K1=515→414), and HCN(J=4-3). These data are combined with data at millimeter wavelengths to derive the volume density and the results are compared to those deduced from millimeter lines alone (Snell et al. 1984). In NGC2024, higher densities (≳ 107 cm−3) are clearly indicated by the sub-mm lines than were derived by Snell et al. In M17, derived densities are also higher, but uncertainties overlap the Snell et al. solutions. The range of densities derived from CS and HCN are consistent. The sub-millimeter lines of these species appear to be good probes of the highest densities present in regions of active star formation.

scholarly journals Star Formation in Galactic Nuclei

1989 ◽  
Vol 120 ◽  
pp. 342-352
Author(s):  
Roberto Terlevich
Keyword(s):  
Star Formation ◽  
Radio Emission ◽  
Active Galactic Nucleus ◽  
Galactic Nuclei ◽  
Emission Lines ◽  
High Luminosity ◽  
Nuclear Activity ◽  
X Ray ◽  
Broad Emission ◽  
Uv Excess

Summary.The term AGN or Active Galactic Nucleus, although with rather ill-defined boundaries, signifies extragalactic systems with non-stellar nuclear activity. Non-stellar activity indicators are: high luminosity, presence of broad emission lines, variability, nuclear UV excess, x-ray emission, radio emission, variable polarization, jets, etc.

scholarly journals IRS spectroscopic studies of ULIRGs at z ~ 2

2012 ◽  
Vol 8 (S295) ◽  
pp. 82-85
Author(s):  
Guanwen Fang ◽  
Xu Kong ◽  
Jia-Sheng Huang ◽  
Zhongyang Ma
Keyword(s):  
Star Formation ◽  
Rest Frame ◽  
Near Infrared ◽  
Infrared Imaging ◽  
Formation Rate ◽  
Spectroscopic Studies ◽  
Formation Processes ◽  
Infrared Galaxies ◽  
Luminous Infrared Galaxies ◽  
Very High

AbstractWe present a result of IRS spectroscopy of 14 Ultra-Luminous Infrared Galaxies (ULIRGs) in the Extended Groth Strip region. These galaxies are massive and have very high star formation rate. Four objects of this sample are detected in the HST/WFC3 near-infrared imaging. They show very diversified rest-frame optical morphologies, including string-like, extended/diffused, and even spiral with a possible bulge, implying different formation processes for these galaxies. We also search for signatures of active galactic nucleus (AGN) in our sample in the X-ray, mid-infrared and radio bands. This sample is dominated by objects with intensive star formation, only 14–29% of them have AGN activities.

Infrared Studies of the Young Stellar Population of 30 Doradus

1980 ◽  
Vol 4 (1) ◽  
pp. 90-92
Author(s):  
P. J. McGregor ◽  
A. R. Hyland
Keyword(s):  
Star Formation ◽  
Stellar Population ◽  
Cluster Formation ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Formation Processes ◽  
Excellent Opportunity ◽  
Infrared Studies ◽  
30 Doradus

The 30 Doradus region offers an excellent opportunity to study cluster formation processes and recent star formation in the Large Magellanic Cloud.

Testing the link between mergers and AGN in the Arp 245 system

2020 ◽  
Vol 15 (S359) ◽  
pp. 192-194
Author(s):  
Elismar Lösch ◽  
Daniel Ruschel-Dutra
Keyword(s):  
Star Formation ◽  
Active Galactic Nucleus ◽  
Spherical Surface ◽  
Galaxy Mergers ◽  
Nuclear Activity ◽  
Upper Limit ◽  
Spherical Surfaces ◽  
Galactic Centers ◽  
Merger Event ◽  
Major Merger

AbstractGalaxy mergers are known to drive an inflow of gas towards galactic centers, potentia- lly leading to both star formation and nuclear activity. In this work we aim to study how a major merger event in the ARP 245 system is linked with the triggering of an active galactic nucleus (AGN) in the NGC galaxy 2992. We employed three galaxy collision numerical simulations and calculated the inflow of gas through four different concentric spherical surfaces around the galactic centers, estimating an upper limit for the luminosity of an AGN being fed the amount of gas crossing the innermost spherical surface. We found that these simulations predict reasonable gas inflow rates when compared with the observed AGN luminosity in NGC 2992.

scholarly journals The global star formation law: from dense cores to extreme starbursts

2006 ◽  
Vol 2 (S237) ◽  
pp. 331-335
Author(s):  
Yu Gao
Keyword(s):  
Star Formation ◽  
Linear Correlation ◽  
Molecular Clouds ◽  
High Redshift ◽  
Gas Content ◽  
Molecular Gas ◽  
Giant Molecular Clouds ◽  
Active Star ◽  
Dense Cores ◽  
The Galaxy

AbstractActive star formation (SF) is tightly related to the dense molecular gas in the giant molecular clouds' dense cores. Our HCN (measure of the dense molecular gas) survey in 65 galaxies (including 10 ultraluminous galaxies) reveals a tight linear correlation between HCN and IR (SF rate) luminosities, whereas the correlation between IR and CO (measure of the total molecular gas) luminosities is nonlinear. This suggests that the global SF rate depends more intimately upon the amount of dense molecular gas than the total molecular gas content. This linear relationship extends to both the dense cores in the Galaxy and the hyperluminous extreme starbursts at high-redshift. Therefore, the global SF law in dense gas appears to be linear all the way from dense cores to extreme starbursts, spanning over nine orders of magnitude in IR luminosity.

scholarly journals Clumpy Galaxies in the Early Universe

2006 ◽  
Vol 2 (S235) ◽  
pp. 376-380 ◽  
Author(s):  
Debra Meloy Elmegreen
Keyword(s):  
Star Formation ◽  
Early Universe ◽  
Spiral Galaxies ◽  
Star Forming ◽  
Wide Range ◽  
Thick Disks ◽  
Hubble Ultra Deep Field

AbstractClumpy galaxies are prominent in the early Universe. We present morphological and photometric properties of a wide range of galaxy types and their star-forming clumps in the Hubble Ultra Deep Field. Sizes, scale lengths, and scale heights suggest that galaxies grow by a factor of 2 fromz= 4 to the present, and that thick disks are present in the early Universe. The largest clumps of star formation are 107–109M⊙in different galaxies, much more massive than large star-forming complexes in local galaxies. Dissolved clumps may account for both the exponential disks and the early thick disks of spirals and proto-spiral galaxies.

scholarly journals Nuclear Activity and the Conditions of Star-formation at the Galactic Center

2017 ◽  
Author(s):  
Andreas Eckart ◽  
Monica Valencia-S. ◽  
B. Shahzamanian ◽  
M. Zajacek ◽  
L. Moser ◽  
...  
Keyword(s):  
Star Formation ◽  
Galactic Center ◽  
Nuclear Activity

scholarly journals Radiative Feedback Effects during Cosmic Reionization

2014 ◽  
Vol 11 (S308) ◽  
pp. 372-377
Author(s):  
David Sullivan ◽  
Ilian T. Iliev
Keyword(s):  
Star Formation ◽  
Radiation Field ◽  
Early Universe ◽  
Galaxy Formation ◽  
Analytical Models ◽  
Feedback Effects ◽  
Radiative Feedback ◽  
Hydrodynamical Simulations ◽  
Matching Models ◽  
The Impact

AbstractWe present coupled radiation hydrodynamical simulations of the epoch of reionization, aimed at probing self-feedback on galactic scales. Unlike previous works, which assume a (quasi) homogeneous UV background, we self-consistently evolve both the radiation field and the gas to model the impact of previously unresolved processes such as spectral hardening and self-shielding. We find that the characteristic halo mass with a gas fraction half the cosmic mean, Mc(z), a quantity frequently used in semi-analytical models of galaxy formation, is significantly larger than previously assumed. While this results in an increased suppression of star formation in the early Universe, our results are consistent with the extrapolated stellar abundance matching models from Moster et al. 2013.

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