scholarly journals The structural properties of classical bulges and discs from z ∼ 2

2019 ◽  
Vol 489 (3) ◽  
pp. 4135-4154 ◽  
Author(s):  
Paola Dimauro ◽  
Marc Huertas-Company ◽  
Emanuele Daddi ◽  
Pablo G Pérez-González ◽  
Mariangela Bernardi ◽  
...  
Keyword(s):  
Structural Properties ◽  
Formation Mechanisms ◽  
Massive Galaxies ◽  
Star Forming ◽  
Star Formation Activity ◽  
Mass Size ◽  
Best Fitting ◽  
The One ◽  
Bulge Formation ◽  
Size Relation

ABSTRACT We study the rest-frame optical mass–size relation of bulges and discs from z ∼ 2 to z ∼ 0 for a complete sample of massive galaxies in the CANDELS fields using two-component Sérsic models. Discs and star-forming galaxies follow similar mass–size relations. The mass–size relation of bulges is less steep than the one of quiescent galaxies (best-fitting slope of 0.7 for quiescent galaxies against 0.4 for bulges). We find little dependence of the structural properties of massive bulges and discs with the global morphology of galaxies (disc versus bulge dominated) and the star formation activity (star-forming versus quiescent). This result suggests similar bulge formation mechanisms for most massive galaxies and also that the formation of the bulge component does not significantly affect the disc structure. Our results pose a challenge to current cosmological models that predict distinct structural properties for stellar bulges arising from mergers and disc instabilities.

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 Extended star-forming regions within galaxies in a dense proto-cluster core at z = 2.53†

2019 ◽  
Vol 71 (4) ◽  
Author(s):  
Tomoko L Suzuki ◽  
Yosuke Minowa ◽  
Yusei Koyama ◽  
Tadayuki Kodama ◽  
Masao Hayashi ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
Structural Evolution ◽  
Cluster Core ◽  
Star Forming ◽  
Spatially Resolved ◽  
Star Forming Regions ◽  
Star Formation Activity ◽  
Radial Profiles ◽  
Structural Growth ◽  
The One

Abstract At z ∼ 2, star formation activity is thought to be high even in high-density environments such as galaxy clusters and proto-clusters. One of the critical but outstanding issues is if the structural growth of star-forming galaxies can differ depending on their surrounding environments. In order to investigate how galaxies grow their structures and what physical processes are involved in the evolution of galaxies, one requires spatially resolved images of not only stellar components but also star-forming regions within galaxies. We conducted (Adaptive Optics) AO-assisted imaging observations for star-forming galaxies in a dense proto-cluster core at z = 2.53 with IRCS and AO188 mounted on the Subaru Telescope. A combination of AO and narrow-band filters allows us to obtain resolved maps of Hα-emitting regions with an angular resolution of ${0{^{\prime\prime}_{.}}1}$–${0{^{\prime\prime}_{.}}2}$, which corresponds to ∼1 kpc at z ∼ 2.5. Based on stacking analyses, we compare radial profiles of star-forming regions and stellar components and find that the star-forming region of a sub-sample with log (M*/$M_\odot$) ∼ 10–11 is more extended than the stellar component, indicating the inside-out growth of the structure. This trend is similar to the one for star-forming galaxies in general fields at z = 2–2.5 obtained with the same observational technique. Our results suggest that the structural evolution of star-forming galaxies at z = 2–2.5 is mainly driven by internal secular processes irrespective of surrounding environments.

scholarly journals The build-up of the outskirts of distant star-forming galaxies at z ~ 2

2016 ◽  
Vol 11 (S321) ◽  
pp. 327-329 ◽  
Author(s):  
Sandro Tacchella ◽  
C. Marcella Carollo ◽  
Avishai Dekel ◽  
Natascha Förster Schreiber ◽  
Alvio Renzini ◽  
...  
Keyword(s):  
Star Formation ◽  
Formation Rate ◽  
Stellar Mass ◽  
Mass Star ◽  
Intermediate Mass ◽  
Massive Galaxies ◽  
Star Forming ◽  
Star Formation Activity ◽  
Dust Attenuation ◽  
Inside Out

AbstractIn order to constrain – and understand – the growth of galaxies, we present a sample of ~ 30 galaxies at z ~ 2 with resolved distribution of stellar mass, star-formation rate, and dust attenuation on scales of ~ 1 kpc. We find that low- and intermediate-mass galaxies grow self-similarly, doubling their stellar mass in the centers and outskirts with the same pace. More massive galaxies (~ 1011 M⊙) have a reduced star-formation activity in their center: they grow mostly in the outskirts (inside-out quenching / formation). Similar trends are find in cosmological zoom-in simulations, highlighting that high stellar mass densities are formed in a gas-rich compaction phase. This nuclear ‘starburst’ phase is followed by a suppressed star-formation activity in the center, resulting in growth of the outskirts. All in all, we put forward that we witness at z ~ 2 the dissipative formation of z = 0 M* early-type galaxies.

scholarly journals Compact, bulge dominated structures of spectroscopically confirmed quiescent galaxies at z ≈ 3

2020 ◽  
Author(s):  
Peter Lustig ◽  
Veronica Strazzullo ◽  
Chiara D’Eugenio ◽  
Emanuele Daddi ◽  
Maurilio Pannella ◽  
...  
Keyword(s):  
Structural Properties ◽  
Surface Brightness ◽  
Cosmic Time ◽  
Stellar Populations ◽  
Statistical Estimates ◽  
The Galaxy ◽  
Mass Size ◽  
Formation And Evolution ◽  
Size Relation ◽  
Good Agreement

Abstract We study structural properties of spectroscopically confirmed massive quiescent galaxies at z ≈ 3 with one of the first sizeable samples of such sources, made of ten 10.8 &lt; log (M⋆/M⊙) &lt; 11.3 galaxies at 2.4 &lt; z &lt; 3.2 in the COSMOS field whose redshifts and quiescence are confirmed by HST grism spectroscopy. Although affected by a weak bias toward younger stellar populations, this sample is deemed to be largely representative of the majority of the most massive and thus intrinsically rarest quiescent sources at this cosmic time. We rely on targeted HST/WFC3 observations and fit Sérsic profiles to the galaxy surface brightness distributions at ≈4000Årestframe. We find typically high Sérsic indices and axis ratios (medians ≈4.5 and 0.73, respectively) suggesting that, at odds with some previous results, the first massive quiescent galaxies may largely be already bulge-dominated systems. We measure compact galaxy sizes with an average of ≈1.4kpc at log (M⋆/M⊙) ≈ 11.2, in good agreement with the extrapolation at the highest masses of previous determinations of the stellar mass - size relation of quiescent galaxies, and of its redshift evolution, from photometrically selected samples at lower and similar redshifts. This work confirms the existence of a population of compact, bulge dominated, massive, quiescent sources at z ≈ 3, providing one of the first statistical estimates of their structural properties, and further constraining the early formation and evolution of the first quiescent galaxies.

scholarly journals HST/WFC3 grism observations of z ∼ 1 clusters: evidence for evolution in the mass–size relation of quiescent galaxies from post-starburst galaxies

2020 ◽  
Vol 493 (4) ◽  
pp. 6011-6032 ◽  
Author(s):  
J Matharu ◽  
A Muzzin ◽  
G B Brammer ◽  
R F J van der Burg ◽  
M W Auger ◽  
...  
Keyword(s):  
Rapid Change ◽  
Driving Mechanism ◽  
Cluster Galaxies ◽  
Star Forming ◽  
Large Size ◽  
The Galaxy ◽  
Size Growth ◽  
Mass Size ◽  
Minor Mergers ◽  
Size Relation

ABSTRACT Minor mergers have been proposed as the driving mechanism for the size growth of quiescent galaxies with decreasing redshift. The process whereby large star-forming galaxies quench and join the quiescent population at the large size end has also been suggested as an explanation for this size growth. Given the clear association of quenching with clusters, we explore this mechanism by studying the structural properties of 23 spectroscopically identified recently quenched (or ‘post-starburst’ (PSB)) cluster galaxies at z ∼ 1. Despite clear PSB spectral signatures implying rapid and violent quenching, 87 per cent of these galaxies have symmetric, undisturbed morphologies in the stellar continuum. Remarkably, they follow a mass–size relation lying midway between the star-forming and quiescent field relations, with sizes 0.1 dex smaller than z ∼ 1 star-forming galaxies at log(M*/M⊙) = 10.5. This implies a rapid change in the light profile without directly effecting the stellar distribution, suggesting changes in the mass-to-light ratio gradients across the galaxy are responsible. We develop fading toy models to explore how star-forming galaxies move across the mass–size plane as their stellar populations fade to match those of the PSBs. ‘Outside-in’ fading has the potential to reproduce the contraction in size and increase in bulge-dominance observed between star-forming and PSB cluster galaxies. Since cluster PSBs lie on the large size end of the quiescent mass–size relation, and our previous work shows cluster galaxies are smaller than field galaxies, the sizes of quiescent galaxies must grow both from the quenching of star-forming galaxies and dry minor mergers.

scholarly journals The impact of the connectivity of the cosmic web on the physical properties of galaxies at its nodes

2019 ◽  
Vol 491 (3) ◽  
pp. 4294-4309 ◽  
Author(s):  
Katarina Kraljic ◽  
Christophe Pichon ◽  
Sandrine Codis ◽  
Clotilde Laigle ◽  
Romeel Davé ◽  
...  
Keyword(s):  
Physical Properties ◽  
Stellar Mass ◽  
Sloan Digital Sky Survey ◽  
Massive Galaxies ◽  
Star Forming ◽  
Star Formation Activity ◽  
Theoretical Predictions ◽  
Hydrodynamical Simulations ◽  
Minor Mergers ◽  
The Impact

ABSTRACT We investigate the impact of the number of filaments connected to the nodes of the cosmic web on the physical properties of their galaxies using the Sloan Digital Sky Survey. We compare these measurements to the cosmological hydrodynamical simulations H orizon-(no)AGN and Simba. We find that more massive galaxies are more connected, in qualitative agreement with theoretical predictions and measurements in dark-matter-only simulations. The star formation activity and morphology of observed galaxies both display some dependence on the connectivity of the cosmic web at a fixed stellar mass: Less star forming and less rotation supported galaxies also tend to have higher connectivity. These results qualitatively hold both for observed and for virtual galaxies, and can be understood given that the cosmic web is the main source of fuel for galaxy growth. The simulations show the same trends at a fixed halo mass, suggesting that the geometry of filamentary infall impacts galaxy properties beyond the depth of the local potential well. Based on simulations, it is also found that active galactic nucleus feedback is key to reversing the relationship between stellar mass and connectivity at a fixed halo mass. Technically, connectivity is a practical observational proxy for past and present accretion (minor mergers or diffuse infall).

scholarly journals Superdense massive galaxies in the nearby universe

2009 ◽  
Vol 5 (S262) ◽  
pp. 331-332
Author(s):  
Anna Ferré-Mateu ◽  
Ignacio Trujillo
Keyword(s):  
Value Added ◽  
Stellar Populations ◽  
Stellar Mass ◽  
Local Universe ◽  
Massive Galaxies ◽  
The Past ◽  
Mass Size ◽  
Size Relation

AbstractAt high-z the most superdense massive galaxies are supposed to be the result of gas-rich mergers resulting in compact remnant (Khochfar & Silk (2006); Naab et al. (2007)). After this, dry mergers are expected to be the mechanism that moves these very massive galaxies towards the current stellar mass size relation. Whitin these merging scenarios, a non-negligible fraction (1-10%) of these galaxies is expected to survive since that epoch retaining their compactness and presenting old stellar populations in the past universe.Using the NYU Value-Added Galaxy Catalog (DR6), we find only a tiny fraction of galaxies (~0.03%) with re ≤ 1.5 kpc and M* ≥ 8x1010M⊙ in the local Universe (z~0.2). Surprisingly, they are relatively young (~2Gyr) and metal rich ([Z/H]~0.2) These results have been published in Trujillo et al. (2009)

scholarly journals Morphology and star formation in IllustrisTNG: the build-up of spheroids and discs

2019 ◽  
Vol 487 (4) ◽  
pp. 5416-5440 ◽  
Author(s):  
Sandro Tacchella ◽  
Benedikt Diemer ◽  
Lars Hernquist ◽  
Shy Genel ◽  
Federico Marinacci ◽  
...  
Keyword(s):  
Star Formation ◽  
Mass Density ◽  
Stellar Mass ◽  
High Mass ◽  
Intermediate Mass ◽  
Massive Galaxies ◽  
Star Forming ◽  
Star Formation Activity ◽  
Stellar Motion ◽  
Galaxy Morphology

ABSTRACT Using the IllustrisTNG simulations, we investigate the connection between galaxy morphology and star formation in central galaxies with stellar masses in the range 109–1011.5 M⊙. We quantify galaxy morphology by a kinematical decomposition of the stellar component into a spheroidal and a disc component (spheroid-to-total ratio, S/T) and by the concentration of the stellar mass density profile (C82). S/T is correlated with stellar mass and star formation activity, while C82 correlates only with stellar mass. Overall, we find good agreement with observational estimates for both S/T and C82. Low- and high-mass galaxies are dominated by random stellar motion, while only intermediate-mass galaxies (M⋆ ≈ 1010–1010.5 M⊙) are dominated by ordered rotation. Whereas higher mass galaxies are typical spheroids with high concentrations, lower mass galaxies have low concentration, pointing to different formation channels. Although we find a correlation between S/T and star formation activity, in the TNG model galaxies do not necessarily change their morphology when they transition through the green valley or when they cease their star formation, this depending on galaxy stellar mass and morphological estimator. Instead, the morphology (S/T and C82) is generally set during the star-forming phase of galaxies. The apparent correlation between S/T and star formation arises because earlier forming galaxies had, on average, a higher S/T at a given stellar mass. Furthermore, we show that mergers drive in situ bulge formation in intermediate-mass galaxies and are responsible for the recent spheroidal mass assembly in the massive galaxies with M⋆ &gt; 1011 M⊙. In particular, these massive galaxies assemble about half of the spheroidal mass while star-forming and the other half through mergers while quiescent.

Cold gas studies of a z = 2.5 protocluster

2020 ◽  
Vol 15 (S359) ◽  
pp. 136-140
Author(s):  
Minju M. Lee ◽  
Ichi Tanaka ◽  
Rohei Kawabe
Keyword(s):  
Galaxy Evolution ◽  
High Redshift ◽  
Kinematic Model ◽  
Molecular Gas ◽  
General View ◽  
Massive Galaxies ◽  
Star Forming ◽  
Gas Kinematics ◽  
Narrow Band Filter ◽  
Stellar Masses

AbstractWe present studies of a protocluster at z =2.5, an overdense region found close to a radio galaxy, 4C 23.56, using ALMA. We observed 1.1 mm continuum, two CO lines (CO (4–3) and CO (3–2)) and the lower atomic carbon line transition ([CI](3P1-3P0)) at a few kpc (0″.3-0″.9) resolution. The primary targets are 25 star-forming galaxies selected as Hα emitters (HAEs) that are identified with a narrow band filter. These are massive galaxies with stellar masses of > 1010Mʘ that are mostly on the galaxy main sequence at z =2.5. We measure the molecular gas mass from the independent gas tracers of 1.1 mm, CO (3–2) and [CI], and investigate the gas kinematics of galaxies from CO (4–3). Molecular gas masses from the different measurements are consistent with each other for detection, with a gas fraction (fgas = Mgas/(Mgas+ Mstar)) of ≃ 0.5 on average but with a caveat. On the other hand, the CO line widths of the protocluster galaxies are typically broader by ˜50% compared to field galaxies, which can be attributed to more frequent, unresolved gas-rich mergers and/or smaller sizes than field galaxies, supported by our high-resolution images and a kinematic model fit of one of the galaxies. We discuss the expected scenario of galaxy evolution in protoclusters at high redshift but future large surveys are needed to get a more general view.

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