GALAXY EVOLUTION THROUGH THE COSMIC TIME

2010 ◽  
Vol 19 (08n10) ◽  
pp. 1371-1377
Author(s):  
T. P. IDIART ◽  
J. A. F. PACHECO ◽  
J. SILK
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Cosmic Time ◽  
Evolutionary Model ◽  
Stellar Populations ◽  
Elliptical Galaxies ◽  
Star Formation Activity ◽  
Formation And Evolution ◽  
The Universe

Elliptical galaxies are the best systems to study the early star formation activity in the universe. This work aims to understand the formation and evolution of these objects through the study of the integrated properties of their stellar populations. Here an evolutionary model is developed and their predicted spectrophotometric properties are presented.

scholarly journals Multiscale cosmic web detachments, connectivity, and preprocessing in the supercluster SCl A2142 cocoon

2020 ◽  
Vol 641 ◽  
pp. A172
Author(s):  
Maret Einasto ◽  
Boris Deshev ◽  
Peeter Tenjes ◽  
Pekka Heinämäki ◽  
Elmo Tempel ◽  
...  
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Stellar Populations ◽  
Main Body ◽  
Low Density ◽  
Very Old ◽  
Global Environmental ◽  
Wide Range ◽  
Local Densities ◽  
The Universe

Context. Superclusters of galaxies and their surrounding low-density regions (cocoons) represent dynamically evolving environments in which galaxies and their systems form and evolve. While evolutionary processes of galaxies in dense environments are extensively studied at present, galaxy evolution in low-density regions has received less attention. Aims. We study the properties, connectivity, and galaxy content of groups and filaments in the A2142 supercluster (SCl A2142) cocoon to understand the evolution of the supercluster with its surrounding structures and the galaxies within them. Methods. We calculated the luminosity-density field of SDSS galaxies and traced the SCl A2142 cocoon boundaries by the lowest luminosity-density regions that separate SCl A2142 from other superclusters. We determined galaxy filaments and groups in the cocoon and analysed the connectivity of groups, the high density core (HDC) of the supercluster, and the whole of the supercluster. We compared the distribution and properties of galaxies with different star-formation properties in the supercluster and in the cocoon. Results. The supercluster A2142 and the long filament that is connected to it forms the longest straight structure in the Universe detected so far, with a length of approximately 75 h−1 Mpc. The connectivity of the cluster A2142 and the whole supercluster is C = 6 − 7; poor groups exhibit C = 1 − 2. Long filaments around the supercluster’s main body are detached from it at the turnaround region. Among various local and global environmental trends with regard to the properties of galaxies and groups, we find that galaxies with very old stellar populations lie in systems across a wide range of richness from the richest cluster to poorest groups and single galaxies. They lie even at local densities as low as D1 <  1 in the cocoon and up to D1 >  800 in the supercluster. Recently quenched galaxies lie in the cocoon mainly in one region and their properties are different in the cocoon and in the supercluster. The star-formation properties of single galaxies are similar across all environments. Conclusions. The collapsing main body of SCl A2142 with the detached long filaments near it are evidence of an important epoch in the supercluster evolution. There is a need for further studies to explore possible reasons behind the similarities between galaxies with very old stellar populations in extremely different environments, as well as mechanisms for galaxy quenching at very low densities. The presence of long, straight structures in the cosmic web may serve as a test for cosmological models.

scholarly journals Mid-IR cosmological spectrophotometric surveys from space: Measuring AGN and star formation at the cosmic noon with a SPICA-like mission

2021 ◽  
Vol 38 ◽  
Author(s):  
Luigi Spinoglio ◽  
Sabrina Mordini ◽  
Juan Antonio Fernández-Ontiveros ◽  
Almudena Alonso-Herrero ◽  
Lee Armus ◽  
...  
Keyword(s):  
Fine Structure ◽  
Star Formation ◽  
Galaxy Evolution ◽  
Formation Rate ◽  
Three Dimensional ◽  
Cosmic Time ◽  
Ir Camera ◽  
Infrared Telescope ◽  
Age Of The Universe ◽  
The Universe

Abstract We use the SPace Infrared telescope for Cosmology and Astrophysics (SPICA) project as a template to demonstrate how deep spectrophotometric surveys covering large cosmological volumes over extended fields (1– $15\, \rm{deg^2}$ ) with a mid-IR imaging spectrometer (17– $36\, \rm{\rm{\upmu m}}$ ) in conjunction with deep $70\, \rm{\rm{\upmu m}}$ photometry with a far-IR camera, at wavelengths which are not affected by dust extinction can answer the most crucial questions in current galaxy evolution studies. A SPICA-like mission will be able for the first time to provide an unobscured three-dimensional (3D, i.e. x, y, and redshift z) view of galaxy evolution back to an age of the universe of less than $\sim$ 2 Gyrs, in the mid-IR rest frame. This survey strategy will produce a full census of the Star Formation Rate (SFR) in the universe, using polycyclic aromatic hydrocarbons (PAH) bands and fine-structure ionic lines, reaching the characteristic knee of the galaxy luminosity function, where the bulk of the population is distributed, at any redshift up to $z \sim 3.5$ . Deep follow-up pointed spectroscopic observations with grating spectrometers onboard the satellite, across the full IR spectral range (17– $210\, \rm{\rm{\upmu m}}$ ), would simultaneously measure Black Hole Accretion Rate (BHAR), from high-ionisation fine-structure lines, and SFR, from PAH and low- to mid-ionisation lines in thousands of galaxies from solar to low metallicities, down to the knee of their luminosity functions. The analysis of the resulting atlas of IR spectra will reveal the physical processes at play in evolving galaxies across cosmic time, especially its heavily dust-embedded phase during the activity peak at the cosmic noon ( $z \sim 1$ –3), through IR emission lines and features that are insensitive to the dust obscuration.

scholarly journals The VIMOS VLT Deep Survey: A census of active and passive galaxies to redshift 1.3

2006 ◽  
Vol 2 (S235) ◽  
pp. 400-400
Author(s):  
D. Vergani
Keyword(s):  
Star Formation ◽  
Cosmic Time ◽  
Late Type ◽  
Limited Sample ◽  
Active Star ◽  
Star Forming ◽  
Star Formation Activity ◽  
Deep Survey ◽  
Stellar Masses ◽  
The Universe

AbstractWe are studying how stellar masses assemble through cosmic time since the Universe had only 30% of its present age. We are conducting a census of galaxies which covers the end of the most active star-forming phase, using a mass-limited sample of approximately 5,000 objects selected from the VIMOS VLT Deep Survey (VVDS) in the redshift range 0.45 < z < 1.3. With a criterion based on the direct spectral measurement of the 4000Å Balmer break, Dn(4000), we have classified our sample in spectroscopically early and late-type galaxies. The trends existing between stellar mass, spectroscopic classification, and star formation activity are clearly shown in our analysis.

scholarly journals The growth of the red-sequence in clusters since ≃1

2009 ◽  
Vol 5 (H15) ◽  
pp. 88-88
Author(s):  
Roberto P. Muñoz ◽  
L. F. Barrientos ◽  
B. P. Koester ◽  
D. G. Gilbank ◽  
M. D. Gladders ◽  
...  
Keyword(s):  
Star Formation ◽  
Galaxy Clusters ◽  
Evolutionary Model ◽  
Large Ensemble ◽  
Cluster Galaxies ◽  
Nir Imaging ◽  
Measured Change ◽  
First Time ◽  
The Universe ◽  
Red Sequence

AbstractWe use deep nIR imaging of 15 galaxy clusters at z ≃ 1 to study the build-up of the red-sequence in rich clusters since the Universe was half its present age. We measured, for the first time, the luminous-to-faint ratio of red-sequence galaxies at z=1 from a large ensemble of clusters, and found an increase of 100% in the ratio of luminous-to-faint red-sequence galaxies from z=0.45 to 1.0. The measured change in this ratio as function of redshift is well-reproduced by a simple evolutionary model developed in this work, that consists in an early truncation of the star formation for bright cluster galaxies and a delayed truncation for faint cluster galaxies.

scholarly journals Satellites and central galaxies in SDSS: the influence of interactions on their properties

2020 ◽  
Vol 501 (1) ◽  
pp. 1046-1058
Author(s):  
Valeria Mesa ◽  
Sol Alonso ◽  
Georgina Coldwell ◽  
Diego García Lambas ◽  
J L Nilo Castellon
Keyword(s):  
Star Formation ◽  
Stellar Population ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Control Sample ◽  
Stellar Populations ◽  
Control Sets ◽  
Central Galaxy ◽  
Star Formation Activity ◽  
Projected Distance

ABSTRACT We use SDSS-DR14 to construct a sample of galaxy systems consisting of a central object and two satellites. We adopt projected distance and radial velocity difference criteria and impose an isolation criterion to avoid membership in larger structures. We also classify the interaction between the members of each system through a visual inspection of galaxy images, finding ${\sim}80{{\ \rm per\ cent}}$ of the systems lack evidence of interactions whilst the remaining ${\sim}20{{\ \rm per\ cent}}$ involve some kind of interaction, as inferred from their observed distorted morphology. We have considered separately, samples of satellites and central galaxies, and each of these samples were tested against suitable control sets to analyse the results. We find that central galaxies showing signs of interactions present evidence of enhanced star formation activity and younger stellar populations. As a counterpart, satellite samples show these galaxies presenting older stellar populations with a lower star formation rate than the control sample. The observed trends correlate with the stellar mass content of the galaxies and with the projected distance between the members involved in the interaction. The most massive systems are less affected since they show no star formation excess, possibly due to their more evolved stage and less gas available to form new stars. Our results suggest that it is arguably a transfer of material during interactions, with satellites acting as donors to the central galaxy. As a consequence of the interactions, satellite stellar population ages rapidly and new bursts of star formation may frequently occur in the central galaxy.

scholarly journals AN EVOLUTIONARY MODEL FOR COLLAPSING MOLECULAR CLOUDS AND THEIR STAR FORMATION ACTIVITY

2012 ◽  
Vol 751 (1) ◽  
pp. 77 ◽  
Author(s):  
Manuel Zamora-Avilés ◽  
Enrique Vázquez-Semadeni ◽  
Pedro Colín
Keyword(s):  
Star Formation ◽  
Molecular Clouds ◽  
Evolutionary Model ◽  
Star Formation Activity

scholarly journals Stellar populations in the highest redshift galaxies

2015 ◽  
Vol 11 (A29B) ◽  
pp. 197-198
Author(s):  
Andrew J. Bunker
Keyword(s):  
Galaxy Evolution ◽  
High Redshift ◽  
Stellar Populations ◽  
Mass Function ◽  
Initial Mass Function ◽  
Star Forming ◽  
Near Ir ◽  
James Webb Space Telescope ◽  
Large Telescopes ◽  
The Universe

AbstractI discuss stellar populations in galaxies at high redshift (z > 6), in particular the blue rest-frame UV colours which have been detected in recent years through near-IR imaging with HST. These spectral slopes of β < −2 are much more blue than star-forming galaxies at lower redshift, and may suggest less dust obscuration, lower metallicity or perhaps a different initial mass function. I describe current work on the luminosity function of high redshift star- forming galaxies, the evolution of the fraction of strong Lyman-α emitters in this population, and the contribution of the ionizing photon budget from such galaxies towards the reionization of the Universe. I also describe constraints placed by Spitzer/IRAC on stellar populations in galaxies within the first billion years, and look towards future developments in spectroscopy with Extremely Large Telescopes and the James Webb Space Telescope, including the JWST/NIRSpec GTO programme on galaxy evolution at high redshift.

scholarly journals The age–chemical abundance structure of the Galactic disc – II. α-dichotomy and thick disc formation

2020 ◽  
Vol 497 (2) ◽  
pp. 2371-2384 ◽  
Author(s):  
Jianhui Lian ◽  
Daniel Thomas ◽  
Claudia Maraston ◽  
Timothy C Beers ◽  
Christian Moni Bidin ◽  
...  
Keyword(s):  
Star Formation ◽  
Cosmic Time ◽  
Theoretical Models ◽  
Bimodal Distribution ◽  
Chemical Abundance ◽  
Secular Evolution ◽  
Thick Disc ◽  
Star Formation Activity ◽  
Gas Accretion ◽  
Disc Formation

ABSTRACT We extend our previous work on the age–chemical abundance structure of the Galactic outer disc to the inner disc (4 &lt; r &lt; 8  kpc) based on the SDSS/APOGEE survey. Different from the outer disc, the inner disc stars exhibit a clear bimodal distribution in the [Mg/Fe]–[Fe/H] plane. While a number of scenarios have been proposed in the literature, it remains challenging to recover this bimodal distribution with theoretical models. To this end, we present a chemical evolution model embedding a complex multiphase inner disc formation scenario that matches the observed bimodal [Mg/Fe]–[Fe/H] distribution. In this scenario, the formation of the inner disc is dominated by two main starburst episodes $6\,$Gyr apart with secular, low-level star formation activity in between. In our model, the first starburst occurs at early cosmic times ($t\sim 1\,$ Gyr) and the second one $6\,$ Gyr later at a cosmic time of $t\sim 7\,$ Gyr. Both these starburst episodes are associated with gas accretion events in our model, and are quenched rapidly. The first starburst leads to the formation of the high-α sequence, and the second starburst leads to the formation of the metal-poor low-α sequence. The metal-rich low-α stars, instead, form during the secular evolution phase between the two bursts. Our model shows that the α-dichotomy originates from the rapid suppression of star formation after the first starburst. The two starburst episodes are likely to be responsible for the formation of the geometric thick disc (z &gt;1 kpc), with the old inner thick disc and the young outer thick disc forming during the first and the second starbursts, respectively.

scholarly journals Michigan 160: a precursor to the LMC?

1991 ◽  
Vol 148 ◽  
pp. 376-377
Author(s):  
L. Staveley-Smith
Keyword(s):  
Star Formation ◽  
Dynamical Evolution ◽  
Stellar Populations ◽  
Detailed Comparison ◽  
Elliptical Galaxies ◽  
Magellanic Clouds ◽  
Formation Processes ◽  
Stellar Formation ◽  
The Galaxy ◽  
Magellanic Stream

The tidal interaction between the Magellanic Clouds and the Galaxy is an important factor in influencing the physical and dynamical evolution of the Clouds (e.g. the Magellanic Stream) as well as the genesis and evolution of their respective stellar populations. However, how important is the influence of the Galaxy? This is a key question since we know that relatively isolated, magellanic-type galaxies do exist (e.g. NGC 3109 and NGC 4449) and have been just as efficient at star-formation as the LMC. It is possible in fact that the star formation in the clouds is primarily stochastic in nature and is relatively insensitive to the global forces which seem to have shaped stellar formation processes in massive spiral and elliptical galaxies. Unsupported by a massive bulge or halo component, cold gas disks are inherently susceptible to radial and bar-like instabilities (Efstathiou et al. 1982) which are very efficient at creating the dynamical pressures required for rapid star-formation. With this in mind, a detailed comparison of 'field' magellanic-type galaxies with the LMC and SMC is of some importance.

scholarly journals The hierarchical evolution of Brightest Cluster Galaxies: red galaxies in a young universe

2012 ◽  
Vol 8 (S295) ◽  
pp. 200-203
Author(s):  
Chiara Tonini
Keyword(s):  
Star Formation ◽  
Stellar Populations ◽  
Star Formation History ◽  
Analytic Model ◽  
Cluster Galaxies ◽  
Star Formation Activity ◽  
Brightest Cluster Galaxies ◽  
Formation History ◽  
Red Galaxies ◽  
Analytic Models

AbstractWe investigate the evolution of Brightest Cluster Galaxies (BCGs) from redshift z ~ 1.6 to z = 0. We upgrade the hierarchical semi-analytic model of Croton et al. (2006) with a new spectro-photometric model that produces realistic galaxy spectra, making use of the Maraston (2005) stellar populations and a new recipe for the dust extinction. We compare the model predictions of the K-band luminosity evolution and the J-K, V-I and I-K colour evolution with a series of datasets, including Collins et al. (Nature, 2009) who argued that semi-analytic models based on the Millennium simulation cannot reproduce the red colours and high luminosity of BCGs at z > 1. We show instead that the model is well in range of the observed luminosity and correctly reproduces the colour evolution of BCGs in the whole redshift range up to z ~ 1.6. We argue that the success of the semi-analytic model is in large part due to the implementation of a more sophisticated spectro-photometric model. An analysis of the model BCGs shows an increase in mass by a factor 2-3 since z ~ 1, and star formation activity down to low redshifts. While the consensus regarding BCGs is that they are passively evolving, we argue that this conclusion is affected by the degeneracy between star formation history and stellar population models used in SED-fitting, and by the inefficacy of toy-models of passive evolution to capture the complexity of real galaxies, especially those with rich merger histories like BCGs. Following this argument, we also show that in the semi-analytic model, the BCGs show a realistic mix of stellar populations, and that these stellar populations are mostly old. In addition, the age-redshift relation of the model BCGs follows that of the Universe, meaning that given their merger history and star formation history, the ageing of BCGs is always dominated by the ageing of their stellar populations. In a ΛCDM Universe, we define such evolution as ‘passive in the hierarchical sense’.

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