scholarly journals The size and mass evolution of the massive galaxies over cosmic time

2012 ◽  
Vol 8 (S295) ◽  
pp. 27-36
Author(s):  
Ignacio Trujillo
Keyword(s):  
Structural Evolution ◽  
Cosmic Time ◽  
Stellar Populations ◽  
Massive Galaxies ◽  
Active Line ◽  
Satellite Galaxies ◽  
Compact Galaxies ◽  
Minor Mergers ◽  
Stellar Properties

AbstractOnce understood as the paradigm of passively evolving objects, the discovery that massive galaxies experienced an enormous structural evolution in the last ten billion years has opened an active line of research. The most significant pending question in this field is the following: which mechanism has made galaxies to grow largely in size without altering their stellar populations properties dramatically? The most viable explanation is that massive galaxies have undergone a significant number of minor mergers which have deposited most of their material in the outer regions of the massive galaxies. This scenario, although appealing, is still far from be observationally proved since the number of satellite galaxies surrounding the massive objects appears insufficient at all redshifts. The presence also of a population of nearby massive compact galaxies with mixture stellar properties is another piece of the puzzle that still does not nicely fit within a comprehensive scheme. I will review these and other intriguing properties of the massive galaxies in this contribution.

scholarly journals Understanding the growth of massive galaxies via stellar populations

2012 ◽  
Vol 8 (S295) ◽  
pp. 125-128
Author(s):  
Ignacio Ferreras
Keyword(s):  
Star Formation ◽  
Formation Process ◽  
Past History ◽  
Stellar Populations ◽  
Open Problems ◽  
Massive Galaxies ◽  
Spectroscopic Observations ◽  
Formation And Evolution ◽  
Minor Mergers ◽  
Star Formation Histories

AbstractThe formation and evolution of massive galaxies represent one of the most intriguing open problems in astrophysics. Their underlying stellar populations encode valuable information about their past history. Detailed spectroscopic observations allow us to constrain the star formation histories, revealing a complicated mixture of a strong, early formation process, followed by passive evolution in the cores, along with an extended assembly of the outer regions via minor mergers. In this contributed talk, some recent results are presented from the analysis of samples of massive galaxies both at z ~ 0 and moderate redshift.

scholarly journals The origin of metallicity gradients in massive galaxies at large radii

2014 ◽  
Vol 10 (S309) ◽  
pp. 117-120
Author(s):  
Michaela Hirschmann ◽  
Thorsten Naab
Keyword(s):  
Empirical Model ◽  
Stellar Population ◽  
Wind Model ◽  
Differential Impact ◽  
Massive Galaxies ◽  
Galactic Winds ◽  
Satellite Galaxies ◽  
Minor Mergers

AbstractWe investigate the origin of stellar metallicity gradients in massive galaxies at large radii (r > 2 Reff) using ten cosmological zoom simulations of halos with 6 × 1012M⊙ < Mhalo < 2 × 1013M⊙. The simulations follow metal cooling and enrichment from SNII, SNIa and AGB winds. We explore the differential impact of an empirical model for galactic winds that reproduces the evolution of the mass-metallicity relation. At larger radii, the galaxies become more dominated by stars accreted from satellite galaxies in major and minor mergers. In the wind model, fewer stars are accreted, but they are significantly more metal poor resulting in steep global metallicity (〈 ▽ Zstars 〉= -0.35 dex/dex) gradients in agreement with observations. Metallicity gradients of models without winds are inconsistent with observations. For the wind model, stellar accretion is steepening existing in-situ metallicity gradients by about 0.2 dex by the present day and is required to match observed gradients. Metallicity gradients are significantly steeper for systems, which have accreted stars in minor mergers. In contrast, galaxies with major mergers have relatively flat gradients, confirming previous results. We highlight the importance of stellar accretion for stellar population properties of massive galaxies at large radii, which provide important constraints for formation models.

scholarly journals Low-mass compact elliptical galaxies: spatially resolved stellar populations and kinematics with the Keck Cosmic Web Imager

2021 ◽  
Vol 503 (4) ◽  
pp. 5455-5472
Author(s):  
Anna Ferré-Mateu ◽  
Mark Durré ◽  
Duncan A Forbes ◽  
Aaron J Romanowsky ◽  
Adebusola Alabi ◽  
...  
Keyword(s):  
Compact Object ◽  
Stellar Populations ◽  
Elliptical Galaxies ◽  
Massive Galaxies ◽  
Spatially Resolved ◽  
Low Mass ◽  
Compact Galaxies ◽  
Stellar Masses ◽  
Star Formation Histories ◽  
First Time

ABSTRACT We present spatially resolved two-dimensional maps and radial trends of the stellar populations and kinematics for a sample of six compact elliptical galaxies (cE) using spectroscopy from the Keck Cosmic Web Imager (KCWI). We recover their star formation histories, finding that all except one of our cEs are old and metal rich, with both age and metallicity decreasing toward their outer radii. We also use the integrated values within one effective radius to study different scaling relations. Comparing our cEs with others from the literature and from simulations we reveal the formation channel that these galaxies might have followed. All our cEs are fast rotators, with relatively high rotation values given their low ellipticites. In general, the properties of our cEs are very similar to those seen in the cores of more massive galaxies, and in particular, to massive compact galaxies. Five out of our six cEs are the result of stripping a more massive (compact or extended) galaxy, and only one cE is compatible with having been formed intrinsically as the low-mass compact object that we see today. These results further confirm that cEs are a mixed-bag of galaxies that can be formed following different formation channels, reporting for the first time an evolutionary link within the realm of compact galaxies (at all stellar masses).

scholarly journals What shapes stellar metallicity gradients of massive galaxies at large radii?

2016 ◽  
Vol 11 (S321) ◽  
pp. 93-95
Author(s):  
Michaela Hirschmann
Keyword(s):  
High Resolution ◽  
Stellar Population ◽  
Stellar Systems ◽  
Differential Impact ◽  
Massive Galaxies ◽  
Physical Mechanisms ◽  
Satellite Galaxies ◽  
Minor Mergers ◽  
The Impact

AbstractWe investigate the differential impact of physical mechanisms, mergers and internal energetic phenomena, on the evolution of stellar metallicity gradients in massive, present-day galaxies employing sets of high-resolution, cosmological zoom simulations. We demonstrate that negative metallicity gradients at large radii (>2Reff) originate from the accretion of metal-poor stellar systems. At larger radii, galaxies become typically more dominated by stars accreted from satellite galaxies in major and minor mergers. However, only strong galactic, stellar-driven winds can sufficiently reduce the metallicity content of the accreted stars to realistically steepen the outer metallicity gradients in agreement with observations. In contrast, the gradients of the models without winds are inconsistent with observations. Moreover, we discuss the impact of additional AGN feedback. This analysis greatly highlights the importance of both energetic processes and merger events for stellar population properties of massive galaxies at large radii. Our results are expected to significantly contribute to the interpretation of current and up-coming IFU surveys (e.g. MaNGA, CALIFA).

scholarly journals THE PROGENITORS OF LOCAL ULTRA-MASSIVE GALAXIES ACROSS COSMIC TIME: FROM DUSTY STAR-BURSTING TO QUIESCENT STELLAR POPULATIONS

2014 ◽  
Vol 794 (1) ◽  
pp. 65 ◽  
Author(s):  
Danilo Marchesini ◽  
Adam Muzzin ◽  
Mauro Stefanon ◽  
Marijn Franx ◽  
Gabriel G. Brammer ◽  
...  
Keyword(s):  
Cosmic Time ◽  
Stellar Populations ◽  
Massive Galaxies

scholarly journals Understanding the size growth of massive galaxies through stellar populations

2015 ◽  
Vol 11 (S319) ◽  
pp. 114-117
Author(s):  
I. Ferreras ◽  
I. Trujillo ◽  
E. Mármol-Queraltó ◽  
P. Pérez-González ◽  
Keyword(s):  
Stellar Populations ◽  
Stellar Mass ◽  
Massive Galaxies ◽  
Significant Process ◽  
Size Growth ◽  
Minor Mergers ◽  
Mass Increase ◽  
Massive Galaxy ◽  
Main Growth

AbstractMassive early-type galaxies undergo a significant process of evolution with redshift on the stellar mass vs size plane. Furthermore, this trend does not depend on the age of their stellar populations. Therefore, such an evolution should involve processes that do not include a significant amount of star formation, leaving (mostly) dry mergers as the main growth channel. By studying close pairs involving a massive galaxy, one can quantify the role of mergers on the growth of massive galaxies. A recent study based on the SHARDS dataset reveals that minor mergers cannot be the dominant mechanism to explain the bulk of size growth in these systems. Merging is found to provide a constant fractional growth rate of ~10% per Gyr from redshift z=1, corresponding to an overall stellar mass increase of 2× between z=1 and z=0.

scholarly journals Minor-merger-driven growth of early-type galaxies over the last 8 billion years

2011 ◽  
Vol 7 (S284) ◽  
pp. 460-464
Author(s):  
S. Kaviraj ◽  
R. M. Crockett ◽  
J. Silk ◽  
R. S Ellis ◽  
S. K. Yi ◽  
...  
Keyword(s):  
Star Formation ◽  
Cosmic Time ◽  
Early Type ◽  
Massive Galaxies ◽  
Evolving Systems ◽  
Star Formation Activity ◽  
Size Evolution ◽  
Major Merger ◽  
Minor Mergers ◽  
Merger Rate

AbstractWe summarise recent progress in understanding the star formation activity in early-type galaxies (ETGs), using recent studies that leverage photometry in the rest-frame ultraviolet (UV) wavelengths. While classically thought to be old, passively-evolving systems, recent UV studies have revealed widespread star formation in ETGs, with ~20% of the stellar mass in today's ETGs forming at late epochs (z < 1). A strong correlation is found between the presence of morphological disturbances and blue UV colours, suggesting that the star formation is merger-driven. However, the major merger rate at late epochs is far too low to satisfy the number of disturbed ETGs, indicating that minor mergers drive the star formation in these galaxies over the latter half of cosmic time. Together with the recent literature which suggests that minor mergers may drive the size evolution of massive ETGs, these results highlight the significant role of minor mergers in driving the evolution of massive galaxies in the low and intermediate-redshift Universe.

scholarly journals The role of mergers and interactions in driving the evolution of dwarf galaxies over cosmic time

2020 ◽  
Vol 500 (4) ◽  
pp. 4937-4957 ◽  
Author(s):  
G Martin ◽  
R A Jackson ◽  
S Kaviraj ◽  
H Choi ◽  
J E G Devriendt ◽  
...  
Keyword(s):  
Star Formation ◽  
Dwarf Galaxies ◽  
Large Fraction ◽  
Structural Evolution ◽  
Cosmic Time ◽  
Stellar Mass ◽  
High Mass ◽  
Key Drivers ◽  
Mass Assembly

ABSTRACT Dwarf galaxies (M⋆ &lt; 109 M⊙) are key drivers of mass assembly in high-mass galaxies, but relatively little is understood about the assembly of dwarf galaxies themselves. Using the NewHorizon cosmological simulation (∼40 pc spatial resolution), we investigate how mergers and fly-bys drive the mass assembly and structural evolution of around 1000 field and group dwarfs up to z = 0.5. We find that, while dwarf galaxies often exhibit disturbed morphologies (5 and 20 per cent are disturbed at z = 1 and z = 3 respectively), only a small proportion of the morphological disturbances seen in dwarf galaxies are driven by mergers at any redshift (for 109 M⊙, mergers drive under 20 per cent morphological disturbances). They are instead primarily the result of interactions that do not end in a merger (e.g. fly-bys). Given the large fraction of apparently morphologically disturbed dwarf galaxies which are not, in fact, merging, this finding is particularly important to future studies identifying dwarf mergers and post-mergers morphologically at intermediate and high redshifts. Dwarfs typically undergo one major and one minor merger between z = 5 and z = 0.5, accounting for 10 per cent of their total stellar mass. Mergers can also drive moderate star formation enhancements at lower redshifts (3 or 4 times at z = 1), but this accounts for only a few per cent of stellar mass in the dwarf regime given their infrequency. Non-merger interactions drive significantly smaller star formation enhancements (around two times), but their preponderance relative to mergers means they account for around 10 per cent of stellar mass formed in the dwarf regime.

The Quest for Relics: Massive compact galaxies in the local Universe

2019 ◽  
Vol 15 (S359) ◽  
pp. 441-443
Author(s):  
F. S. Lohmann ◽  
A. Schnorr-Müller ◽  
M. Trevisan ◽  
R. Riffel ◽  
N. Mallmann ◽  
...  
Keyword(s):  
High Redshift ◽  
Control Sample ◽  
Sloan Digital Sky Survey ◽  
Integral Field Spectroscopy ◽  
Sky Survey ◽  
Size Evolution ◽  
Compact Galaxies ◽  
Minor Mergers ◽  
Significant Size ◽  
Integral Field

AbstractObservations at high redshift reveal that a population of massive, quiescent galaxies (called red nuggets) already existed 10 Gyr ago. These objects undergo a significant size evolution over time, likely due to minor mergers. In this work we present an analysis of local massive compact galaxies to assess if their properties are consistent with what is expected for unevolved red nuggets (relic galaxies). Using integral field spectroscopy (IFS) data from the MaNGA survey from the Sloan Digital Sky Survey (SDSS), we characterized the kinematics and properties of stellar populations of massive compact galaxies, and find that these objects exhibit, on average, a higher rotational support than a control sample of average sized early-type galaxies. This is in agreement with a scenario in which these objects have a quiet accretion history, rendering them candidates for relic galaxies.

scholarly journals The weak imprint of environment on the stellar populations of galaxies

2020 ◽  
Vol 500 (4) ◽  
pp. 4469-4490 ◽  
Author(s):  
James Trussler ◽  
Roberto Maiolino ◽  
Claudia Maraston ◽  
Yingjie Peng ◽  
Daniel Thomas ◽  
...  
Keyword(s):  
Environmental Effects ◽  
Unique Feature ◽  
Stellar Populations ◽  
Stellar Mass ◽  
Sloan Digital Sky Survey ◽  
Star Forming ◽  
Sky Survey ◽  
Satellite Galaxies ◽  
Projected Distance ◽  
Environmental Dependence

ABSTRACT We investigate the environmental dependence of the stellar populations of galaxies in Sloan Digital Sky Survey Data Release 7 (SDSS DR7). Echoing earlier works, we find that satellites are both more metal-rich (&lt;0.1 dex) and older (&lt;2 Gyr) than centrals of the same stellar mass. However, after separating star-forming, green valley, and passive galaxies, we find that the true environmental dependence of both stellar metallicity (&lt;0.03 dex) and age (&lt;0.5 Gyr) is in fact much weaker. We show that the strong environmental effects found when galaxies are not differentiated result from a combination of selection effects brought about by the environmental dependence of the quenched fraction of galaxies, and thus we strongly advocate for the separation of star-forming, green valley, and passive galaxies when the environmental dependence of galaxy properties are investigated. We also study further environmental trends separately for both central and satellite galaxies. We find that star-forming galaxies show no environmental effects, neither for centrals nor for satellites. In contrast, the stellar metallicities of passive and green valley satellites increase weakly (&lt;0.05 and &lt;0.08 dex, respectively) with increasing halo mass, increasing local overdensity and decreasing projected distance from their central; this effect is interpreted in terms of moderate environmental starvation (‘strangulation’) contributing to the quenching of satellite galaxies. Finally, we find a unique feature in the stellar mass–stellar metallicity relation for passive centrals, where galaxies in more massive haloes have larger stellar mass (∼0.1 dex) at constant stellar metallicity; this effect is interpreted in terms of dry merging of passive central galaxies and/or progenitor bias.

Sign in / Sign up

Export Citation Format

Share Document