Assembly bias evidence in close galaxy pairs

ABSTRACT The growth channel of massive galaxies involving mergers can be studied via close pairs as putative merger progenitors, where the stellar populations of the satellite galaxies will be eventually incorporated into the massive primaries. We extend our recent analysis of the GAMA-based sample of close pairs presented in Ferreras et al. to the general spectroscopic data set of SDSS galaxies (DR14), for which the high S/N of the data enables a detailed analysis of the differences between satellite galaxies with respect to the mass of the primary galaxy. A sample of approximately 2000 satellites of massive galaxies is carefully selected within a relatively narrow redshift range (0.07<z<0.14). Two main parameters are considered as major drivers of the star formation history of these galaxies, namely: the stellar velocity dispersion of the satellite (σ), as a proxy of ‘local’ drivers, and the ratio between the stellar mass of the satellite and the primary, μ = MSAT/MPRI, meant to serve as an indicator of environment. Consistently with the independent, GAMA-based work, we find that satellites around the most massive primaries appear older, at fixed velocity dispersion, than satellites of lower mass primaries. This trend is more marked in lower mass satellites (σ ∼ 100 km s−1), with SSP-equivalent age differences up to ∼0.5 Gyr, and can be interpreted as a one-halo assembly bias, so that satellites corresponding to smaller values of μ represent older structures, akin to fossil groups.

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Starburst Feedback in Local, Massive Galaxies

Proceedings of the International Astronomical Union ◽

10.1017/s1743921306006600 ◽

2006 ◽

Vol 2 (S235) ◽

pp. 280-283

Author(s):

Crystal L. Martin

Keyword(s):

Surface Brightness ◽

Milky Way ◽

Velocity Dispersion ◽

Rotation Speed ◽

Far Infrared ◽

Elliptical Galaxies ◽

Evolutionary Path ◽

Sky Surveys ◽

Massive Galaxies ◽

Stellar Velocity

Major mergers of gas-rich galaxies, each comparable in mass to the Milky Way, are rare at the present epoch. These events were readily identifed, however, two decades ago in far-infrared sky surveys (Soifer et al. 1986, 1987). Removal of the dust enshrouding these starbursts was almost immediately proposed as an evolutionary path to quasar formation (Sanders 1988). Recent measurements of the stellar velocity dispersion, rotation speed, and stellar surface brightness profile of these mergers suggest ULIRGs are indeed progenitors of field elliptical galaxies (Genzel et al. 2001; Tacconi et al. 2002).

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Stellar velocity dispersions and emission line properties of SDSS-III/BOSS galaxies

Proceedings of the International Astronomical Union ◽

10.1017/s174392131300450x ◽

2012 ◽

Vol 8 (S295) ◽

pp. 129-132

Author(s):

D. Thomas ◽

O. Steele ◽

C. Maraston ◽

J. Johansson ◽

A. Beifiori ◽

...

Keyword(s):

Emission Line ◽

Velocity Dispersion ◽

Target Selection ◽

Emission Lines ◽

Clear Correlation ◽

Data Set ◽

Star Forming ◽

Public Data ◽

Data Release ◽

Stellar Velocity

AbstractWe perform a spectroscopic analysis of 492,450 galaxy spectra from the first two years of observations of the Sloan Digital Sky Survey-III/Baryonic Oscillation Spectroscopic Survey (BOSS) collaboration. This data set has been released in the ninth SDSS data release, the first public data release of BOSS spectra. We show that the typical signal-to-noise ratio of BOSS spectra is sufficient to measure stellar velocity dispersion and emission line fluxes for individual objects. The typical velocity dispersion of a BOSS galaxy is 240 km/s, with an accuracy of better than 30 per cent for 93 per cent of BOSS galaxies. The distribution in velocity dispersion is redshift independent between redshifts 0.15 and 0.7, which reflects the survey design targeting massive galaxies with an approximately uniform mass distribution in this redshift interval. The majority of BOSS galaxies lack detectable emission lines. We analyse the emission line properties and present diagnostic diagrams using the emission lines [OII], Hβ, [OIII], Halpha, and [NII] (detected in about 4 per cent of the galaxies). We show that the emission line properties are strongly redshift dependent and that there is a clear correlation between observed frame colours and emission line properties. Within in the low-z sample around 0.15 < z < 0.3, half of the emission-line galaxies have LINER-like emission line ratios, followed by Seyfert-AGN dominated spectra, and only a small fraction of a few per cent are purely star forming galaxies. AGN and LINER-like objects, instead, are less prevalent in the high-z sample around 0.4 < z < 0.7, where more than half of the emission line objects are star forming. This is a pure selection effect caused by the non-detection of weak Hβ emission lines in the BOSS spectra. Finally, we show that star forming, AGN and emission line free galaxies are well separated in the g - r vs r - i target selection diagram.

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Star Formation Through Cosmic Time

Proceedings of the International Astronomical Union ◽

10.1017/s1743921306006557 ◽

2006 ◽

Vol 2 (S235) ◽

pp. 261-267

Author(s):

Michael A. Dopita

Keyword(s):

Star Formation ◽

Galaxy Formation ◽

Globular Clusters ◽

High Redshift ◽

Cosmic Time ◽

Star Formation History ◽

Massive Black Holes ◽

Massive Galaxies ◽

History Of ◽

Population Iii Stars

AbstractThis paper reviews the star formation history of the Universe, from the first stars to the current day, with emphasis on the critical analysis of the techniques that have been used to determine it, especially considering the role of dust. We consider the first population of stars, the Population III stars, were formed at redshifts ranging as high as z ~ 60, the formation of the Globular Clusters, the main epoch of galaxy formation. In the sub-mm galaxies and high-redshift radio galaxies the collapse of massive galaxies was surprisingly rapid, and that the growth of super-massive black holes at their centers provides the energy input to eject the galactic interstellar medium while at the same time precipitating a final burst of star formation and the ejection of their ISM so that the subsequent evolution of these galaxies is passive.

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Tomography of the Ie-Re and L-Sigma Planes

Universe ◽

10.3390/universe8010008 ◽

2021 ◽

Vol 8 (1) ◽

pp. 8

Author(s):

Mauro D’Onofrio ◽

Cesare Chiosi

Keyword(s):

Star Formation ◽

Velocity Dispersion ◽

Past History ◽

Small Range ◽

Stellar Content ◽

The Past ◽

Total Luminosity ◽

Stellar Velocity ◽

History Of ◽

Physical Foundation

We have analyzed the distribution of early-type galaxies (ETGs) in the effective surface intensity vs. effective radius (Ie−Re) plane and in the total luminosity vs. central stellar velocity dispersion (L−σ) diagram, with the aim of studying the physical variables that allow the transformation of one space-parameter into the other. We find that the classical Faber–Jackson relation L=L0σα, in which the parameters L0 and α are confined in a small range of possible values, is incompatible with the distribution observed in the Ie−Re plane. The two distributions become mutually consistent only if luminosity is not considered a pure proxy of mass but a variable tightly dependent on the past history of mass assembling and star formation and on the present evolutionary state of the stellar content of a galaxy. The solution comes by considering the L=L0′σβ law proposed by D’Onofrio et al. in 2020, in which both L0′ and β can vary considerably from galaxy to galaxy. We will also show that the data of the Illustris numerical simulation prove the physical foundation of the L=L0′σβ law and confirm the prediction of the Zone of Exclusion (ZoE) originating from the intersection of the virial law with the L=L0′σβ relation. The ZoE is the region in the Ie−Re and Re−Ms diagrams avoided by real galaxies, and the border of which marks the condition of ‘full’ virial equilibrium with no recent significant merger events and no undergoing star formation.

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Star formation history of the solar neighbourhood as told by Gaia

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3576 ◽

2020 ◽

Vol 501 (1) ◽

pp. 302-328

Author(s):

Jairo A Alzate ◽

Gustavo Bruzual ◽

Daniel J Díaz-González

Keyword(s):

Star Formation ◽

Binary Stars ◽

Mass Function ◽

Initial Mass Function ◽

Star Formation History ◽

Solar Neighbourhood ◽

Data Set ◽

Formation History ◽

Solar Metallicity ◽

History Of

ABSTRACT The Gaia data release 2 (DR2) catalogue is the best source of stellar astrometric and photometric data available today. The history of the Milky Way galaxy is written in stone in this data set. Parallaxes and photometry tell us where the stars are today, when were they formed, and with what chemical content, that is, their star formation history (SFH). We develop a Bayesian hierarchical model suited to reconstruct the SFH of a resolved stellar population. We study the stars brighter than $G\, =\, 15$ within 100 pc of the Sun in Gaia DR2 and derive an SFH of the solar neighbourhood in agreement with previous determinations and improving upon them because we detect chemical enrichment. Our results show a maximum of star formation activity about 10 Gyr ago, producing large numbers of stars with slightly below solar metallicity (Z = 0.014), followed by a decrease in star formation up to a minimum level occurring around 8 Gyr ago. After a quiet period, star formation rises to a maximum at about 5 Gyr ago, forming stars of solar metallicity (Z = 0.017). Finally, star formation has been decreasing until the present, forming stars of Z = 0.03 at a residual level. We test the effects introduced in the inferred SFH by ignoring the presence of unresolved binary stars in the sample, reducing the apparent limiting magnitude, and modifying the stellar initial mass function.

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Size, shade, or shape? The contribution of galaxies of different types to the star formation history of the Universe from SDSS-IV MaNGA

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab268 ◽

2021 ◽

Vol 502 (3) ◽

pp. 3128-3143

Author(s):

Thomas Peterken ◽

Alfonso Aragón-Salamanca ◽

Michael Merrifield ◽

Vladimir Avila-Reese ◽

Nicholas F Boardman ◽

...

Keyword(s):

Star Formation ◽

Sloan Digital Sky Survey ◽

Star Formation History ◽

Fourth Generation ◽

Massive Galaxies ◽

Formation History ◽

Galaxy Sample ◽

History Of ◽

Stellar Masses ◽

The Universe

ABSTRACT By fitting stellar populations to the fourth generation of the Sloan Digital Sky Survey (SDSS-IV) Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey observations of ∼7000 suitably weighted individual galaxies, we reconstruct the star formation history of the Universe, which we find to be in reasonable agreement with previous studies. Dividing the galaxies by their present-day stellar mass, we demonstrate the downsizing phenomenon, whereby the more massive galaxies hosted the most star formation at earlier times. Further dividing the galaxy sample by colour and morphology, we find that a galaxy’s present-day colour tells us more about its historical contribution to the cosmic star formation history than its current morphology. We show that downsizing effects are greatest among galaxies currently in the blue cloud, but that the level of downsizing in galaxies of different morphologies depends quite sensitively on the morphological classification used, due largely to the difficulty in classifying the smaller low-mass galaxies from their ground-based images. Nevertheless, we find agreement that among galaxies with stellar masses $M_{\star } \gt 6\times 10^{9}\, \mathrm{ M}_{\odot }$, downsizing is most significant in spirals. However, there are complicating factors. For example, for more massive galaxies, we find that colour and morphology are predictors of the past star formation over a longer time-scale than in less massive systems. Presumably this effect is reflecting the longer period of evolution required to alter these larger galaxies’ physical properties, but shows that conclusions based on any single property do not tell the full story.

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Velocity dispersion of brightest cluster galaxies in cosmological simulations

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab2518 ◽

2021 ◽

Vol 507 (4) ◽

pp. 5780-5795

Author(s):

I Marini ◽

S Borgani ◽

A Saro ◽

G L Granato ◽

C Ragone-Figueroa ◽

...

Keyword(s):

Dark Matter ◽

Velocity Dispersion ◽

Stellar Envelope ◽

Cluster Galaxies ◽

Massive Galaxies ◽

Brightest Cluster Galaxies ◽

Stellar Velocity ◽

Intracluster Light ◽

The Universe ◽

Good Agreement

ABSTRACT Using the DIANOGA hydrodynamical zoom-in simulation set of galaxy clusters, we analyse the dynamics traced by stars belonging to the brightest cluster galaxies (BCGs) and their surrounding diffuse component, forming the intracluster light (ICL), and compare it to the dynamics traced by dark matter and galaxies identified in the simulations. We compute scaling relations between the BCG and cluster velocity dispersions and their corresponding masses (i.e. $M_\mathrm{BCG}^{\star }$–$\sigma _\mathrm{BCG}^{\star }$, M200–σ200, $M_\mathrm{BCG}^{\star }$–M200, and $\sigma _\mathrm{BCG}^{\star }$–σ200), we find in general a good agreement with observational results. Our simulations also predict $\sigma _\mathrm{BCG}^{\star }$–σ200 relation to not change significantly up to redshift z = 1, in line with a relatively slow accretion of the BCG stellar mass at late times. We analyse the main features of the velocity dispersion profiles, as traced by stars, dark matter, and galaxies. As a result, we discuss that observed stellar velocity dispersion profiles in the inner cluster regions are in excellent agreement with simulations. We also report that the slopes of the BCG velocity dispersion profile from simulations agree with what is measured in observations, confirming the existence of a robust correlation between the stellar velocity dispersion slope and the cluster velocity dispersion (thus, cluster mass) when the former is computed within 0.1R500. Our results demonstrate that simulations can correctly describe the dynamics of BCGs and their surrounding stellar envelope, as determined by the past star formation and assembly histories of the most massive galaxies of the Universe.

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