scholarly journals Star Formation Efficiency at Intermediate Redshift

2012 ◽  
Vol 8 (S292) ◽  
pp. 303-306
Author(s):  
F. Combes ◽  
S. García-Burillo ◽  
J. Braine ◽  
E. Schinnerer ◽  
F. Walter ◽  
...  
Keyword(s):  
Star Formation ◽  
Conversion Factor ◽  
High Redshift ◽  
Star Formation History ◽  
Gas Content ◽  
Formation History ◽  
Luminous Galaxies ◽  
Formation Efficiency ◽  
Intermediate Redshift

AbstractStar formation is evolving very fast in the second half of the Universe, and it is as yet unclear whether this is due to evolving gas content, or evolving star formation efficiency (SFE). We have carried out a survey of ultra-luminous galaxies (ULIRG) between z = 0.2 and 1, to check the gas fraction in this domain of redshift which is still poorly known. Our survey with the IRAM-30m detected 33 galaxies out of 69, and we derive a significant evolution of both the gas fraction and SFE of ULIRGs over the whole period, and in particular a turning point around z = 0.35. The result is sensitive to the CO-to-H2 conversion factor adopted, and both gas fraction and SFE have comparable evolution, when we adopt the low starburst conversion factor of α = 0.8 M⊙ (K km s−1 pc2)−1. Adopting a higher α will increase the role of the gas fraction. Using α = 0.8, the SFE and the gas fraction for z∼0.2-1.0 ULIRGs are found to be significantly higher, by a factor 3, than for local ULIRGs, and are comparable to high redshift ones. We compare this evolution to the expected cosmic H2 abundance and the cosmic star formation history.

scholarly journals Molecular Gas in Galaxies at all Redshifts

2010 ◽  
Vol 6 (S277) ◽  
pp. 47-54
Author(s):  
Françoise Combes
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Star Formation History ◽  
Gas Content ◽  
Continuum Emission ◽  
Massive Galaxies ◽  
Normal Galaxies ◽  
Galaxy Type ◽  
Formation History ◽  
Formation Efficiency

AbstractI review some recent results about the molecular content of galaxies, obtained essentially from the CO lines, but also dense tracers, or the dust continuum emission. New results have been obtained on molecular cloud physics, and their efficiency to form stars, shedding light on the Kennicutt-Schmidt law as a function of surface density and galaxy type. Large progress has been made on galaxy at moderate and high redshifts, allowing to interprete the star formation history and star formation efficiency as a function of gas content, or galaxy evolution. In massive galaxies, the gas fraction was higher in the past, and galaxy disks were more unstable and more turbulent. ALMA observations will allow the study of more normal galaxies at high z with higher spatial resolution and sensitivity.

scholarly journals Is there enough star formation in simulated protoclusters?

2020 ◽  
Vol 501 (2) ◽  
pp. 1803-1822
Author(s):  
Seunghwan Lim ◽  
Douglas Scott ◽  
Arif Babul ◽  
David J Barnes ◽  
Scott T Kay ◽  
...  
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
Star Formation History ◽  
Test Case ◽  
Numerical Resolution ◽  
Formation History ◽  
Order Of Magnitude ◽  
History Of ◽  
Hydrodynamical Simulations ◽  
Formation Efficiency

ABSTRACT As progenitors of the most massive objects, protoclusters are key to tracing the evolution and star formation history of the Universe, and are responsible for ${\gtrsim }\, 20$ per cent of the cosmic star formation at $z\, {\gt }\, 2$. Using a combination of state-of-the-art hydrodynamical simulations and empirical models, we show that current galaxy formation models do not produce enough star formation in protoclusters to match observations. We find that the star formation rates (SFRs) predicted from the models are an order of magnitude lower than what is seen in observations, despite the relatively good agreement found for their mass-accretion histories, specifically that they lie on an evolutionary path to become Coma-like clusters at $z\, {\simeq }\, 0$. Using a well-studied protocluster core at $z\, {=}\, 4.3$ as a test case, we find that star formation efficiency of protocluster galaxies is higher than predicted by the models. We show that a large part of the discrepancy can be attributed to a dependence of SFR on the numerical resolution of the simulations, with a roughly factor of 3 drop in SFR when the spatial resolution decreases by a factor of 4. We also present predictions up to $z\, {\simeq }\, 7$. Compared to lower redshifts, we find that centrals (the most massive member galaxies) are more distinct from the other galaxies, while protocluster galaxies are less distinct from field galaxies. All these results suggest that, as a rare and extreme population at high z, protoclusters can help constrain galaxy formation models tuned to match the average population at $z\, {\simeq }\, 0$.

scholarly journals ROLE OF GALAXY MERGERS IN COSMIC STAR FORMATION HISTORY

2009 ◽  
Vol 697 (2) ◽  
pp. 1764-1783 ◽  
Author(s):  
Yong Shi ◽  
George Rieke ◽  
Jennifer Lotz ◽  
Pablo G. Perez-Gonzalez
Keyword(s):  
Star Formation ◽  
Star Formation History ◽  
Galaxy Mergers ◽  
Formation History

scholarly journals Dissecting the Formation Histories of Galaxies with Stellar Populations Models

2009 ◽  
Vol 5 (S262) ◽  
pp. 153-163
Author(s):  
Ivo Labbé
Keyword(s):  
Star Formation ◽  
Current Knowledge ◽  
High Redshift ◽  
Local Environment ◽  
Stellar Populations ◽  
Current Data ◽  
Star Formation History ◽  
Spectral Energy ◽  
Formation History ◽  
History Of

AbstractHow did galaxies evolve from primordial fluctuations to the well-ordered but diverse population of disk and elliptical galaxies that we observe today? Stellar populations synthesis models have become a crucial tool in addressing this question by helping us to interpret the spectral energy distributions of present-day galaxies and their high redshift progenitors in terms of fundamental characteristics such as stellar mass and age. I will review our current knowledge on the evolution of stellar populations in early- and late type galaxies at z < 1 and the tantalizing – but incomplete – view of the stellar populations in galaxies at 1 < z < 3, during the global peak of star formation. Despite great progress, many fundamental questions remain: what processes trigger episodes of galaxy-scale star formation and what quenches them? To what degree does the star formation history of galaxies depend on the merger history, (halo) mass, or local environment? I will discuss some of the challenges posed in interpreting current data and what improved results might be expected from new observational facilities in the near- and more distant future.

scholarly journals Modelling Stellar Populations at High Redshift

2010 ◽  
Vol 6 (S277) ◽  
pp. 158-165
Author(s):  
Claudia Maraston
Keyword(s):  
Star Formation ◽  
High Redshift ◽  
Stellar Populations ◽  
Star Formation History ◽  
Population Modelling ◽  
Massive Galaxies ◽  
Star Forming ◽  
Formation History ◽  
Derived Properties ◽  
Stellar Masses

AbstractStellar populations carry information about the formation of galaxies and their evolution up to the present epoch. A wealth of observational data are available nowadays, which are analysed with stellar population models in order to obtain key properties such as ages, star formation histories, stellar masses. Differences in the models and/or in the assumptions regarding the star formation history affect the derived properties as much as differences in the data. I shall review the interpretation of high-redshift galaxy data from a model perspective. While data quality dominates galaxy analysis at the highest possible redshifts (z > 5), population modelling effects play the major part at lower redshifts. In particular, I discuss the cases of both star-forming galaxies at the peak of the cosmic star formation history as well as passive galaxies at redshift below 1 that are often used as cosmological probes. Remarks on the bridge between low and high-z massive galaxies conclude the contribution.

scholarly journals HUBBLE SPACE TELESCOPEGRISM SPECTROSCOPY OF EXTREME STARBURSTS ACROSS COSMIC TIME: THE ROLE OF DWARF GALAXIES IN THE STAR FORMATION HISTORY OF THE UNIVERSE

2014 ◽  
Vol 789 (2) ◽  
pp. 96 ◽  
Author(s):  
Hakim Atek ◽  
Jean-Paul Kneib ◽  
Camilla Pacifici ◽  
Matthew Malkan ◽  
Stephane Charlot ◽  
...  
Keyword(s):  
Star Formation ◽  
Dwarf Galaxies ◽  
Cosmic Time ◽  
Star Formation History ◽  
Formation History ◽  
History Of ◽  
The Universe

scholarly journals High-redshift galaxies in the Hubble Deep Field: colour selection and star formation history to z   4

1996 ◽  
Vol 283 (4) ◽  
pp. 1388-1404 ◽  
Author(s):  
P. Madau ◽  
H. C. Ferguson ◽  
M. E. Dickinson ◽  
M. Giavalisco ◽  
C. C. Steidel ◽  
...  
Keyword(s):  
Star Formation ◽  
High Redshift ◽  
Star Formation History ◽  
High Redshift Galaxies ◽  
Formation History ◽  
Hubble Deep Field ◽  
Redshift Galaxies

scholarly journals The ALMA Spectroscopic Survey Large Program: The Infrared Excess of z = 1.5–10 UV-selected Galaxies and the Implied High-redshift Star Formation History

2020 ◽  
Vol 902 (2) ◽  
pp. 112 ◽  
Author(s):  
Rychard Bouwens ◽  
Jorge González-López ◽  
Manuel Aravena ◽  
Roberto Decarli ◽  
Mladen Novak ◽  
...  
Keyword(s):  
Star Formation ◽  
High Redshift ◽  
Star Formation History ◽  
Infrared Excess ◽  
Large Program ◽  
Formation History

Propeties of H alpha emitters at z ∼ 2.3: Derivation of H alpha luminosity from multi-band photometry

2019 ◽  
Vol 15 (S341) ◽  
pp. 316-317
Author(s):  
Yasunori Terao ◽  
Lee Spitler ◽  
Kentaro Motohara
Keyword(s):  
Star Formation ◽  
Formation Rate ◽  
Broad Band ◽  
Star Formation History ◽  
Dust Extinction ◽  
Large Numbers ◽  
Formation History ◽  
Luminous Galaxies ◽  
History Of ◽  
Individual Galaxy

AbstractThe measurement of Hα luminosity for large numbers of galaxies is important to investigate recent star formation history of galaxies. With SED fitting that includes emission line templates, we extract individual galaxy Hα luminosities from broad-band photometry. We compare Hα luminosity function with the result of a narrow-band survey, HiZELS, and find there are more luminous galaxies in Hα than previously reported. As a result, our derived star formation rate density at z ∼ 2.3 turns out to be 2.2 times higher than previous studies. Most of the offset in the results can be explained by missing Hα in the HiZELS photometric aperture and different methods for dust extinction correction.

scholarly journals Dwarf Galaxies: From the Epoch of Peak Star Formation to the Epoch of Reionization

2018 ◽  
Vol 14 (S344) ◽  
pp. 429-436
Author(s):  
Hakim Atek
Keyword(s):  
Star Formation ◽  
Dwarf Galaxies ◽  
High Redshift ◽  
Great Part ◽  
Star Formation History ◽  
Dark Matter Halos ◽  
Galaxy Surveys ◽  
Formation History ◽  
History Of ◽  
Low Mass

AbstractDwarf galaxies represent the dominant population at high redshift and they most likely contributed in great part to star formation history of the Universe and cosmic reionization. The importance of dwarf galaxies at high redshift has been mostly recognized in the last decade due to large progress in observing facilities allowing deep galaxy surveys to identify low-mass galaxies. This population appear to have extreme emission lines and ionizing properties that challenge stellar population models. Star formation follows a stochastic process in these galaxies, which has important implication on the ionizing photon production and its escape fraction whose measurements are challenging for both simulations and observations. Outstanding questions include: what are the physical properties at the origin of such extreme properties? What are the smallest dark matter halos that host star formation? Are dwarf galaxies responsible for cosmic reionization?

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