Structural evolution of massive early-type galaxies

2012 ◽  
Vol 8 (S295) ◽  
pp. 204-207
Author(s):  
Ludwig Oser ◽  
Thorsten Naab ◽  
Jeremiah P. Ostriker ◽  
Peter H. Johansson
Keyword(s):  
Structural Evolution ◽  
Central Line ◽  
Dominant Mode ◽  
Strong Increase ◽  
Massive Galaxies ◽  
Stellar Velocity ◽  
Mass Size ◽  
Velocity Dispersions ◽  
Stellar Mergers ◽  
Loss Of Compactness

AbstractWe use a large sample of cosmological re-simulations of individual massive galaxies to investigate the origin of the strong increase in sizes and weak decrease of the stellar velocity dispersions since z = 2. At the end of a rapid early phase of star-formation, where stars are created from infalling cold gas, our simulated galaxies are all compact with projected half-mass radii of ≲ 1 kpc and central line-of-sight velocity dispersions of ≈ 262 km s−1. At lower redshifts (z < 2) those galaxies grow predominantly by the accretion of smaller stellar systems and evolve towards the observed local mass-size and mass-velocity dispersion relations. This loss of compactness is accompanied with an increase of central dark matter fractions. We find that the structural evolution of massive galaxies can be explained by frequent minor stellar mergers, which is the dominant mode of accretion for our simulated galaxies.

scholarly journals Black hole feedback and the evolution of massive early-type galaxies

2019 ◽  
Author(s):  
Ignacio Martín-Navarro ◽  
Joseph N Burchett ◽  
Mar Mezcua
Keyword(s):  
Black Hole ◽  
Galaxy Formation ◽  
Theoretical Understanding ◽  
Massive Black Holes ◽  
Massive Galaxies ◽  
Hot Gas ◽  
The Galaxy ◽  
Stellar Velocity ◽  
Mass Size ◽  
Galaxy Halo

Abstract Observationally, constraining the baryonic cycle within massive galaxies has proven to be quite difficult. In particular, the role of black hole feedback in regulating star formation, a key process in our theoretical understanding of galaxy formation, remains highly debated. We present here observational evidence showing that, at fixed stellar velocity dispersion, the temperature of the hot gas is higher for those galaxies hosting more massive black holes in their centers. Analyzed in the context of well-established scaling relations, particularly the mass–size plane, the relation between the mass of the black hole and the temperature of the hot gas around massive galaxies provides further observational support to the idea that baryonic processes within massive galaxies are regulated by the combined effects of the galaxy halo virial temperature and black hole feedback, in agreement with the expectations from the EAGLE cosmological numerical simulation.

scholarly journals Structural analysis of massive galaxies using HST deep imaging at z < 0.5

2020 ◽  
Vol 634 ◽  
pp. A11
Author(s):  
Sandra N. dos Reis ◽  
Fernando Buitrago ◽  
Polychronis Papaderos ◽  
Israel Matute ◽  
José Afonso ◽  
...  
Keyword(s):  
Surface Brightness ◽  
Structural Parameters ◽  
Structural Evolution ◽  
Morphological Type ◽  
Formation Mechanisms ◽  
Massive Galaxies ◽  
Local Mass ◽  
Mass Size ◽  
Mass Assembly ◽  
Size Relation

Context. The most massive galaxies (Mstellar ≥ 1011 M⊙) in the local Universe are characterized by a bulge-dominated morphology and old stellar populations, in addition to being confined to a tight mass-size relation. Identifying their main components can provide insights into their formation mechanisms and subsequent mass assembly. Aims. Taking advantage of Hubble Space Telescope (HST) CANDELS data, we analyze the lowest redshift (z <  0.5) massive galaxies in the H and I band in order to disentangle their structural constituents and study possible faint non-axisymmetric features. Methods. Our final sample consists of 17 massive galaxies. Due to the excellent HST spatial resolution for intermediate redshift objects, they are hard to model by purely automatic parametric fitting algorithms. We performed careful single and double (bulge-disk decompositions) Sérsic fits to their galaxy surface brightness profiles. We compare the model color profiles with the observed ones and also derive multi-component global effective radii attempting to obtain a better interpretation of the mass-size relation. Additionally, we test the robustness of our measured structural parameters via simulations. Results. We find that the Sérsic index does not offer a good proxy for the visual morphological type for our sample of massive galaxies. Our derived multi-component effective radii give a better description of the size of our sample galaxies than those inferred from single Sérsic models with GALFIT. Our galaxy population lies on the scatter of the local mass-size relation, indicating that these massive galaxies have not experienced a significant growth in size since z ∼ 0.5. Interestingly, the few outliers are late-type galaxies, indicating that spheroids must reach the local mass-size relation earlier. For most of our sample galaxies, both single- and multi-component Sérsic models with GALFIT show substantial systematic deviations from the observed surface brightness profiles in the outskirts. These residuals may be partly due to several factors, namely a nonoptimal data reduction for low surface brightness features or the existence of prominent stellar haloes for massive galaxies, or they could also arise from conceptual shortcomings of parametric 2D image decomposition tools. They consequently propagate into galaxy color profiles. This is a significant obstacle to the exploration of the structural evolution of galaxies, which calls for a critical assessment and refinement of existing surface photometry techniques.

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 Evolution of the dust emission of massive galaxies up toz= 4 and constraints on their dominant mode of star formation

2015 ◽  
Vol 573 ◽  
pp. A113 ◽  
Author(s):  
Matthieu Béthermin ◽  
Emanuele Daddi ◽  
Georgios Magdis ◽  
Claudia Lagos ◽  
Mark Sargent ◽  
...  
Keyword(s):  
Star Formation ◽  
Dust Emission ◽  
Dominant Mode ◽  
Massive Galaxies

scholarly journals Stellar Populations and Kinematics in Seyfert Galaxies

2006 ◽  
Vol 2 (S235) ◽  
pp. 71-75 ◽  
Author(s):  
N. V. Asari ◽  
L. R. Vega ◽  
A. Garcia-Rissmann ◽  
R. M. González Delgado ◽  
T. Storchi-Bergmann ◽  
...  
Keyword(s):  
Equivalent Width ◽  
Correlation Method ◽  
Seyfert Galaxies ◽  
Population Synthesis ◽  
Stellar Kinematics ◽  
Spatially Resolved ◽  
Fitting Method ◽  
Stellar Velocity ◽  
Velocity Dispersions ◽  
Nuclear Signal

AbstractOur aim is to study the stellar kinematics in hosts of AGN. We do so by measuring nuclear stellar velocity dispersions (σ⋆). Our sample comprises spectra of 78 objects, 69 of which are Seyfert galaxies, in the region around the λλ8498.02, 8542.09, 8662.14 Calcium triplet (CaT). We investigate two methods to measure σ⋆: (1) the direct fitting method (DFM), which makes use of our stellar population synthesis code Starlight, and (2) the cross-correlation method (CCM), for which we use the fxcor package in IRAF. Both methods yield velocity dispersions consistent to within 19 km/s on-average. We have also measured the CaT equivalent width (WCaT) and the λ3933 CaII K equivalent width (WK) for the objects in our sample. Other studies have shown that WK is a powerful tracer of starbursts in Seyfert nuclei, so we check if WCaT can be used in the same way. We have also analysed a sub-sample of 34 spatially resolved objects with reasonably good off-nuclear signal-to-noise. We study the spatial variations of both σ⋆ and WCaT. We see no dilution in WCaT for composite starburst + Seyfert 2 galaxies, in contrast to the dilution in the WK (studied by other authors) for the same objects.

scholarly journals Stellar velocity dispersions in AGN – I. Observational results

2004 ◽  
Vol 2004 (IAUS222) ◽  
pp. 195-196
Author(s):  
L. R. Vega Neme ◽  
R. Cid Fernandes ◽  
A. Garcia Rissman ◽  
N. Vale Asari ◽  
R. M. González Delgado ◽  
...  
Keyword(s):  
Stellar Velocity ◽  
Velocity Dispersions

scholarly journals Starburst Feedback in Local, Massive Galaxies

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).

Measuring Stellar Velocity Dispersions in Active Galaxies

2006 ◽  
Vol 641 (1) ◽  
pp. 117-132 ◽  
Author(s):  
Jenny E. Greene ◽  
Luis C. Ho
Keyword(s):  
Active Galaxies ◽  
Stellar Velocity ◽  
Velocity Dispersions

scholarly journals The Fundamental Plane of cluster spheroidal galaxies at z ∼ 1.3: evidence for mass-dependent evolution

2019 ◽  
Vol 491 (2) ◽  
pp. 1777-1794 ◽  
Author(s):  
P Saracco ◽  
A Gargiulo ◽  
F La Barbera ◽  
M Annunziatella ◽  
D Marchesini
Keyword(s):  
Mass Density ◽  
High Redshift ◽  
Structural Evolution ◽  
Stellar Populations ◽  
Mass Function ◽  
Initial Mass Function ◽  
Fundamental Plane ◽  
Stellar Velocity ◽  
A Minor ◽  
Mass Dependent

ABSTRACT We present spectroscopic observations obtained at the Large Binocular Telescope in the field of the cluster XLSSJ0223−0436 at z = 1.22. We confirm 12 spheroids cluster members and determine stellar velocity dispersion for 7 of them. We combine these data with those in the literature for clusters RXJ0848+4453 at z = 1.27 (8 galaxies) and XMMJ2235−2557 at z = 1.39 (7 galaxies) to determine the Fundamental Plane (FP) of cluster spheroids. We find that the FP at z ∼ 1.3 is offset and rotated (∼3σ) with respect to the local FP. The offset corresponds to a mean evolution Δlog(Mdyn/LB) = (−0.5 ± 0.1)z. High-redshift galaxies follow a steeper mass-dependent Mdyn/LB–Mdyn relation than local ones. Assuming Δ log(Mdyn/LB) = Δ log(M*/LB), higher mass galaxies [log(Mdyn/M⊙) ≥ 11.5] have a higher formation redshift (zf ≥ 6.5) than lower mass ones [zf ≤2 for log(Mdyn/M⊙ ≤ 10)], with a median zf ≃ 2.5 for the whole sample. Also, galaxies with higher stellar mass density host stellar populations formed earlier than those in lower density galaxies. At fixed initial mass function, Mdyn/M* varies systematically with mass and mass density. It follows that the evolution of the stellar populations (M*/LB) accounts for the observed evolution of Mdyn/LB for Mdyn > 1011 M⊙ galaxies, while accounts for ∼85 per cent of the evolution at Mdyn < 1011 M⊙. We find no evidence in favour of structural evolution of individual galaxies, while we find evidences that spheroids later added to the population may account for the observed discrepancy between Δlog(Mdyn/LB) and Δ log(M*/LB) at masses <1011 M⊙. Thus, the evolution of the FP of cluster spheroids is consistent with the mass-dependent and mass density-dependent evolution of their stellar populations superimposed to a minor contribution of spheroids joining the population at later times.

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