scholarly journals Probing the Cosmic Frontier of Galaxies

2015 ◽  
Vol 11 (A29B) ◽  
pp. 808-811
Author(s):  
Pascal A. Oesch
Keyword(s):  
Galaxy Formation ◽  
Mass Density ◽  
Formation Rate ◽  
Big Bang ◽  
Ir Camera ◽  
Blank Field ◽  
Open Questions ◽  
First Galaxies ◽  
The Big Bang ◽  
The Universe

AbstractUnderstanding when and how the first galaxies formed and what sources reionized the universe are key goals of extragalactic astronomy. Thanks to deep surveys with the powerful WFC3/IR camera on the HST, the observational frontier of galaxy build-up now lies at only ~450 Myr after the Big Bang, at redshifts z ~10-12. In combination with deep data from Spitzer/IRAC we can now probe the evolution of the stellar mass density over 96% of cosmic history. However, detecting and characterizing galaxies at these early epochs is challenging even for HST and the sample sizes at the earliest redshifts are still very small. The Hubble Frontier Fields provide a prime new dataset to improve upon our current, sparse sampling of the UV luminosity function at z>8 from blank fields to answer some of the most pressing open questions. For instance, even the evolution of the cosmic star-formation rate density at z>8 is still debated. While our measurements based on blank field data indicate that galaxies with SFR>0.7 Msol/yr disappear quickly from the cosmic record between z~8 and z~10, other previous results, e.g., from the CLASH survey favor a more moderate decline. Here, we briefly review the recent progress in studying galaxy build-up out to z~10 from the combined blank field and existing Frontier Field datasets and discuss their implications for primordial galaxy formation and cosmic reionization.

Linear Growth of Cosmological Perturbations

2013 ◽  
Author(s):  
Abraham Loeb ◽  
Steven R. Furlanetto
Keyword(s):  
Galaxy Formation ◽  
Big Bang ◽  
Density Fluctuations ◽  
Microwave Background ◽  
Cosmological Recombination ◽  
Small Density ◽  
Evolution Of Structure ◽  
First Galaxies ◽  
The Big Bang ◽  
The Universe

This chapter shows that, after cosmological recombination, the Universe had entered the “dark ages,” during which the relic cosmic microwave background (CMB) light from the Big Bang gradually faded away. During this “pregnancy” period (which lasted hundreds of millions of years), the seeds of small density fluctuations planted by inflation in the matter distribution grew until they eventually collapsed to make the first galaxies. In addition to the density evolution, the second key “initial condition” for galaxy formation is the temperature of the hydrogen and helium gas that had likewise collapsed into the first galaxies. Here, the chapter describes the first stages of these processes and introduces the methods conventionally used to describe the fluctuations. It follows the evolution of structure in the linear regime, when the perturbations are small.

The First Stars

2013 ◽  
Author(s):  
Abraham Loeb ◽  
Steven R. Furlanetto
Keyword(s):  
Phase Transition ◽  
Early Universe ◽  
Galaxy Formation ◽  
Big Bang ◽  
First Stars ◽  
Complex Chemical ◽  
Radiative Processes ◽  
Complex Processes ◽  
The Big Bang ◽  
The Universe

This chapter considers the emergence of the complex chemical and radiative processes during the first stages of galaxy formation. It studies the appearance of the first stars, their feedback processes, and the resulting ionization structures that emerged during and shortly after the cosmic dawn. The formation of the first stars tens or hundreds of millions of years after the Big Bang had marked a crucial transition in the early Universe. Before this point, the Universe was elegantly described by a small number of parameters. But as soon as the first stars formed, more complex processes entered the scene. To illustrate this, the chapter provides a brief outline of the prevailing (though observationally untested) theory for this cosmological phase transition.

Dynamical aspects of galaxy clustering

1980 ◽  
Vol 296 (1419) ◽  
pp. 339-345 ◽  
Keyword(s):  
Galaxy Formation ◽  
Gravitational Instability ◽  
Mass Density ◽  
Big Bang ◽  
Density Fluctuations ◽  
Galaxy Clustering ◽  
Origin And Evolution ◽  
Statistical Measures ◽  
Instability Theory ◽  
The Universe

Some recent work on the origin and evolution of galaxy clustering is reviewed, particularly within the context of the gravitational instability theory and the hot big-bang cosmological model. Statistical measures of clustering, including correlation functions and multiplicity functions, are explained and discussed. The close connection between galaxy formation and clustering is emphasized. Additional topics include the dependence of galaxy clustering on the spectrum of primordial density fluctuations and the mean mass density of the Universe.

scholarly journals The first galaxies at cm and mm wavelengths

2006 ◽  
Vol 2 (14) ◽  
pp. 263-263
Author(s):  
Fabian Walter ◽  
Chris L. Carilli ◽  
Frank Bertoldi ◽  
Pierre Cox ◽  
Karl M. Menten
Keyword(s):  
Galaxy Formation ◽  
Elliptical Galaxy ◽  
Big Bang ◽  
Host Galaxy ◽  
Host Galaxies ◽  
Dynamical Mass ◽  
Normal Galaxies ◽  
Resolution Imaging ◽  
First Galaxies ◽  
The Big Bang

AbstractObservations of the most distant (z≃6) QSOs in the centimetre and millimetre regime currently serve as the only direct probe of the host galaxies of these extreme systems in the Epoch of Re-ionization. Such observations reveal that about 1'3 of the hosts contain massive reservoirs of dust (>108M⊙) and molecular gas (>1010M⊙) – the fuel for galaxy formation, and also indicate coeval starbursts at a rate >103M⊙yr−1 adequate to form a large elliptical galaxy in a dynamical timescale. These data imply that a highly metal enriched, molecular ISM, can be generated in galaxies within 870 Myr of the Big Bang. High-resolution imaging of the gas also provide an estimate of the host galaxy dynamical mass. However, current observations are restricted to rare, hyper-luminous IR galaxies. I will close by considering the prospects of observing the gas, dust, and star formation in the first ‘normal’ galaxies (e.g., the Ly-α galaxies) into cosmic reionization (z>6), using ALMA and the EVLA.

scholarly journals Possible Constituents of Halos

1987 ◽  
Vol 117 ◽  
pp. 395-409
Author(s):  
Martin J. Rees
Keyword(s):  
Galaxy Formation ◽  
Massive Stars ◽  
Critical Density ◽  
Big Bang ◽  
Galactic Halos ◽  
Low Mass Stars ◽  
Groups Of Galaxies ◽  
Low Mass ◽  
The Big Bang ◽  
The Universe

There still seem to be three serious contenders for the dark matter in galactic halos and groups of galaxies: (i) very low mass stars, (ii) black hole remnants of very massive stars or (iii) some species of particle (e.g. axions, photinos, etc.) surviving from the big bang. There are genuine prospects of detecting individual objects in all three of these categories, and thereby narrowing down the present range of options. If the Universe has the critical density (Ω = 1), rather than the lower value (Ω = 0.1–0.2) inferred from dynamical evidence, then the galaxies must be more clustered than the overall distribution even on scales 10–20 Mpc. “Biased” galaxy formation could account for this.

Cosmology

2017 ◽  
Author(s):  
Nicholas Manton ◽  
Nicholas Mee
Keyword(s):  
Galaxy Formation ◽  
Large Scale ◽  
Cosmological Parameters ◽  
Big Bang ◽  
Newtonian Gravity ◽  
Microwave Background ◽  
Cosmological Redshift ◽  
Frw Model ◽  
The Big Bang ◽  
The Universe

This chapter is about the large-scale structure of the universe, how it is described in general relativity and recent advances in determining the cosmological parameters. The Hubble distance–redshift relationship is discussed. The assumptions of the FRW cosmologies are presented and the FRW solutions of Einstein equation are derived. The FRW model is interpreted in terms of Newtonian gravity. Cosmological redshift is explained. The evidence for dark matter and its possible origin are discussed. The evidence for the Big Bang is presented, including the cosmic microwave background and the latest measurements of the CMB by the Planck probe. The evidence for dark energy is discussed, along with its interpretation as an FRW cosmology with a non-zero cosmological constant. Computer models of galaxy formation are discussed. Outstanding cosmological puzzles are presented along with their possible solution by inflationary models.

scholarly journals Joint Discussion 7 The Universe at zz>6

2006 ◽  
Vol 2 (14) ◽  
pp. 245-245
Author(s):  
Daniel Schaerer ◽  
Andrea Ferrara (eds)
Keyword(s):  
Galaxy Formation ◽  
Big Bang ◽  
First Stars ◽  
Dark Ages ◽  
Important Challenge ◽  
The Big Bang ◽  
The Universe

The exploration of the earliest phase of star and galaxy formation after the Big Bang remains an important challenge of contemporary astrophysics and represents a key science driver for numerous future facilities. During this phase the first stars and galaxies appear and start to light up and ionize the then neutral Universe ending thereby the so called cosmic dark ages and leading progressively to the complete reionization we observe now at redshift z≃6 or earlier.

scholarly journals The limits of cosmology: role of the Moon

2020 ◽  
Vol 379 (2188) ◽  
pp. 20190561 ◽  
Author(s):  
Joseph Silk
Keyword(s):  
Galaxy Formation ◽  
Star Clusters ◽  
Far Infrared ◽  
Big Bang ◽  
Habitable Zone ◽  
The Moon ◽  
The Big Bang ◽  
The Universe ◽  
Infrared Telescopes

The lunar surface allows a unique way forward in cosmology, to go beyond current limits. The far side provides an unexcelled radio-quiet environment for probing the dark ages via 21 cm interferometry to seek elusive clues on the nature of the infinitesimal fluctuations that seeded galaxy formation. Far-infrared telescopes in cold and dark lunar polar craters will probe back to the first months of the Big Bang and study associated spectral distortions in the CMB. Optical and IR megatelescopes will image the first star clusters in the Universe and seek biosignatures in the atmospheres of unprecedented numbers of nearby habitable zone exoplanets. The goals are compelling and a stable lunar platform will enable construction of telescopes that can access trillions of modes in the sky, providing the key to exploration of our cosmic origins. This article is part of a discussion meeting issue ‘Astronomy from the Moon: the next decades’.

scholarly journals Intense starbursts at z~5: first significant stellar mass assembly in the progenitors of present-day spheroids

2007 ◽  
Vol 3 (S245) ◽  
pp. 471-476
Author(s):  
Aprajita Verma ◽  
Matthew Lehnert ◽  
Natascha Förster Schreiber ◽  
Malcolm Bremer ◽  
Laura Douglas
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
Large Scale ◽  
Star Formation Rate ◽  
Mass Density ◽  
High Redshift ◽  
Formation Rate ◽  
Big Bang ◽  
Stellar Mass ◽  
Mass Assembly

AbstractHigh redshift galaxies play a key role in our developing understanding of galaxy formation and evolution. Since such galaxies are being studied within a Gyr of the big bang, they provide a unique probe of the physics of one of the first generations of large-scale star-formation. We have performed a complete statistical study of the physical properties of a robust sample of z~5 UV luminous galaxies selected using the Lyman-break technique. The characteristic properties of this sample differ from LBGs at z~3 of comparable luminosity in that they are a factor of ten less massive (~few×109 M⊙) and the majority (~70%) are considerably younger (<100Myr). Our results support no more than a modest decline in the global star formation rate density at high redshifts and suggest that ~1% of the stellar mass density of the universe had already assembled at z~5. The constraint derived for the latter is affected by their young ages and short duty cycles which imply existing z~5 LBG samples may be highly incomplete. These intense starbursts have high unobscured star formation rate surface densities (~100s M⊙ yr−1 kpc−2), suggesting they drive outflows and winds that enrich the intra- and inter-galactic media with metals. These properties imply that the majority of z~5 LBGs are in formation meaning that most of their star-formation has likely occurred during the last few crossing times. They are experiencing their first (few) generations of large-scale star formation and are accumulating their first significant stellar mass. As such, z~5 LBGs are the likely progenitors of the spheroidal components of present-day massive galaxies (supported by their high stellar mass surface densities and their core phase-space densities).

scholarly journals Investigating the growing population of massive quiescent galaxies at cosmic noon

2020 ◽  
Vol 499 (3) ◽  
pp. 4239-4260
Author(s):  
Sydney Sherman ◽  
Shardha Jogee ◽  
Jonathan Florez ◽  
Matthew L Stevans ◽  
Lalitwadee Kawinwanichakij ◽  
...  
Keyword(s):  
Main Sequence ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Big Bang ◽  
Physical Mechanisms ◽  
Hydrodynamical Simulations ◽  
Analytic Models ◽  
The Big Bang ◽  
The Universe ◽  
Growing Population

ABSTRACT We explore the build-up of quiescent galaxies using a sample of 28 469 massive (M⋆ ≥ 1011 M⊙) galaxies at redshifts 1.5 &lt; $z$ &lt; 3.0, drawn from a 17.5 deg2 area (0.33 Gpc3 comoving volume at these redshifts). This allows for a robust study of the quiescent fraction as a function of mass at 1.5 &lt; $z$ &lt; 3.0 with a sample ∼40 times larger at log(M⋆/$\rm M_{\odot })\ge 11.5$ than previous studies. We derive the quiescent fraction using three methods: specific star formation rate, distance from the main sequence, and UVJ colour–colour selection. All three methods give similar values at 1.5 &lt; $z$ &lt; 2.0, however the results differ by up to a factor of 2 at 2.0 &lt; $z$ &lt; 3.0. At redshifts 1.5 &lt; $z$ &lt; 3.0, the quiescent fraction increases as a function of stellar mass. By $z$ = 2, only 3.3 Gyr after the big bang, the universe has quenched ∼25 per cent of M⋆ = 1011 M⊙ galaxies and ∼45 per cent of M⋆ = 1012 M⊙ galaxies. We discuss physical mechanisms across a range of epochs and environments that could explain our results. We compare our results with predictions from hydrodynamical simulations SIMBA and IllustrisTNG and semi-analytic models (SAMs) SAG, SAGE, and Galacticus. The quiescent fraction from IllustrisTNG is higher than our empirical result by a factor of 2–5, while those from SIMBA and the three SAMs are lower by a factor of 1.5–10 at 1.5 &lt; $z$ &lt; 3.0.

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