scholarly journals The Redshift and Star Formation Mode of AzTEC2: A Pair of Massive Galaxies at z = 4.63

2020 ◽  
Vol 890 (2) ◽  
pp. 171 ◽  
Author(s):  
E. F. Jiménez-Andrade ◽  
J. A. Zavala ◽  
B. Magnelli ◽  
C. M. Casey ◽  
D. Liu ◽  
...  
Keyword(s):  
Star Formation ◽  
Massive Galaxies ◽  
Formation Mode

scholarly journals Quenching by gas compression and consumption

2019 ◽  
Vol 624 ◽  
pp. A81 ◽  
Author(s):  
Allison W. S. Man ◽  
Matthew D. Lehnert ◽  
Joël D. R. Vernet ◽  
Carlos De Breuck ◽  
Theresa Falkendal
Keyword(s):  
Star Formation ◽  
Formation Rate ◽  
Relative Strength ◽  
Star Formation History ◽  
Molecular Gas ◽  
Host Galaxies ◽  
Massive Galaxies ◽  
Star Forming ◽  
Gas Compression ◽  
Formation History

The objective of this work is to study how active galactic nuclei (AGN) influence star formation in host galaxies. We present a detailed investigation of the star-formation history and conditions of a z = 2.57 massive radio galaxy based on VLT/X-shooter and ALMA observations. The deep rest-frame ultraviolet spectrum contains photospheric absorption lines and wind features indicating the presence of OB-type stars. The most significantly detected photospheric features are used to characterize the recent star formation: neither instantaneous nor continuous star-formation history is consistent with the relative strength of the Si IIλ1485 and S Vλ1502 absorption. Rather, at least two bursts of star formation took place in the recent past, at 6+1-2 Myr and ≳20 Myr ago, respectively. We deduce a molecular H2 gas mass of (3.9 ± 1.0) × 1010 M⊙ based on ALMA observations of the [C I] 3P2−3P1 emission. The molecular gas mass is only 13% of its stellar mass. Combined with its high star-formation rate of (1020-170+190 M⊙ yr-1, this implies a high star-formation efficiency of (26 ± 8) Gyr−1 and a short depletion time of (38 ± 12) Myr. We attribute the efficient star formation to compressive gas motions in order to explain the modest velocity dispersions (⩽55 km s−1) of the photospheric lines and of the star-forming gas traced by [C I]. Because of the likely very young age of the radio source, our findings suggest that vigorous star formation consumes much of the gas and works in concert with the AGN to remove any residual molecular gas, and eventually quenching star formation in massive galaxies.

scholarly journals Assembly Histories and Observational Properties of Simulated Early-type Galaxies

2012 ◽  
Vol 8 (S295) ◽  
pp. 354-357
Author(s):  
Peter H. Johansson
Keyword(s):  
Star Formation ◽  
Initial Growth ◽  
Early Type ◽  
Massive Galaxies ◽  
Main Galaxy ◽  
Two Phases ◽  
Late Growth ◽  
Kinematic Properties

AbstractWe demonstrate that massive simulated galaxies assemble in two phases, with the initial growth dominated by compact in situ star formation, whereas the late growth is dominated by accretion of old stars formed in subunits outside the main galaxy. We also show that 1) gravitational feedback strongly suppresses late star formation in massive galaxies contributing to the observed galaxy colour bimodality that 2) the observed galaxy downsizing can be explained naturally in the two-phased model and finally that 3) the details of the assembly histories of massive galaxies are directly connected to their observed kinematic properties.

scholarly journals The evolution of massive galaxies in semi-analytical models of galaxy formation

2012 ◽  
Vol 8 (S295) ◽  
pp. 191-199
Author(s):  
Carlton M. Baugh
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
Formation Process ◽  
Hierarchical Models ◽  
Gravitational Instability ◽  
Stellar Populations ◽  
Analytical Models ◽  
Massive Galaxies ◽  
Current State ◽  
The Galaxy

AbstractMassive galaxies with old stellar populations have been put forwards as a challenge to models in which cosmic structures grow hierarchically through gravitational instability. I will explain how the growth of massive galaxies is helped by features of hierarchical models. I give a brief outline of how the galaxy formation process is modelled in hierarchical cosmologies using semi-analytical models, and illustrate how these models can be refined as our understanding of processes such as star formation improves. I then present a brief survey of the current state of play in the modelling of massive galaxies and list some outstanding challenges.

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 Star-Forming Galaxies at Cosmic Noon

2020 ◽  
Vol 58 (1) ◽  
pp. 661-725 ◽  
Author(s):  
Natascha M. Förster Schreiber ◽  
Stijn Wuyts
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Star Formation History ◽  
Massive Galaxies ◽  
Star Forming ◽  
Dense Cores ◽  
Gravitational Instabilities ◽  
James Webb Space Telescope ◽  
Formation History ◽  
Large Telescopes

Ever deeper and wider look-back surveys have led to a fairly robust outline of the cosmic star-formation history, which culminated around [Formula: see text]; this period is often nicknamed “cosmic noon.” Our knowledge about star-forming galaxies at these epochs has dramatically advanced from increasingly complete population censuses and detailed views of individual galaxies. We highlight some of the key observational insights that influenced our current understanding of galaxy evolution in the equilibrium growth picture: ▪  Scaling relations between galaxy properties are fairly well established among massive galaxies at least out to [Formula: see text], pointing to regulating mechanisms already acting on galaxy growth. ▪  Resolved views reveal that gravitational instabilities and efficient secular processes within the gas- and baryon-rich galaxies at [Formula: see text] play an important role in the early buildup of galactic structure. ▪  Ever more sensitive observations of kinematics at [Formula: see text] are probing the baryon and dark matter budget on galactic scales and the links between star-forming galaxies and their likely descendants. ▪  Toward higher masses, massive bulges, dense cores, and powerful AGNs and AGN-driven outflows are more prevalent and likely play a role in quenching star formation. We outline emerging questions and exciting prospects for the next decade with upcoming instrumentation, including the James Webb Space Telescope and the next generation of extremely large telescopes.

scholarly journals MMT/MMIRS spectroscopy of z = 1.3 - 2.4 extreme [O iii] emitters: implications for galaxies in the reionization era

2019 ◽  
Vol 489 (2) ◽  
pp. 2572-2594 ◽  
Author(s):  
Mengtao Tang ◽  
Daniel P Stark ◽  
Jacopo Chevallard ◽  
Stéphane Charlot
Keyword(s):  
Star Formation ◽  
Radiation Field ◽  
Production Efficiency ◽  
Rest Frame ◽  
Optical Emission ◽  
Intense Line ◽  
Massive Galaxies ◽  
Stellar Masses ◽  
The Impact ◽  
Intense Radiation

ABSTRACT Galaxies in the reionization era have been shown to have prominent [O iii] + H β emission. Little is known about the gas conditions and radiation field of this population, making it challenging to interpret the spectra emerging at z ≳ 6. Motivated by this shortcoming, we have initiated a large MMT spectroscopic survey identifying rest-frame optical emission lines in 227 intense [O iii] emitting galaxies at 1.3 < z < 2.4. This sample complements the MOSDEF and KBSS surveys, extending to much lower stellar masses ($10^7\!-\!10^8 \, \mathrm{M}_\odot$) and larger specific star formation rates (5–300 Gyr−1), providing a window on galaxies directly following a burst or recent upturn in star formation. The hydrogen ionizing production efficiency (ξion) is found to increase with the [O iii] equivalent width (EW), in a manner similar to that found in local galaxies. We describe how this relationship helps explain the anomalous success rate in identifying Ly α emission in z ≳ 7 galaxies with strong [O iii] + H β emission. We probe the impact of the intense radiation field on the ISM using O32 and Ne3O2, two ionization-sensitive indices. Both are found to scale with the [O iii] EW, revealing extreme ionization conditions not commonly seen in older and more massive galaxies. In the most intense line emitters, the indices have very large average values (O32 = 9.1, Ne3O2 = 0.5) that have been shown to be linked to ionizing photon escape. We discuss implications for the nature of galaxies most likely to have O32 values associated with significant LyC escape. Finally we consider the optimal strategy for JWST spectroscopic investigations of galaxies at z ≳ 10 where the strongest rest-frame optical lines are no longer visible with NIRSpec.

scholarly journals Galaxies hosting an active galactic nucleus: a view from the CALIFA survey

2020 ◽  
Vol 492 (3) ◽  
pp. 3073-3090 ◽  
Author(s):  
Eduardo A D Lacerda ◽  
Sebastián F Sánchez ◽  
R Cid Fernandes ◽  
Carlos López-Cobá ◽  
Carlos Espinosa-Ponce ◽  
...  
Keyword(s):  
Star Formation ◽  
Morphological Type ◽  
Molecular Gas ◽  
Main Role ◽  
Type I ◽  
Massive Galaxies ◽  
Star Forming ◽  
Integral Field Spectroscopy ◽  
Almost All ◽  
Formation Efficiency

ABSTRACT We study the presence of optically-selected active galactic nuclei (AGNs) within a sample of 867 galaxies extracted from the extended Calar-Alto Legacy Integral Field spectroscopy Area (eCALIFA) spanning all morphological classes. We identify 10 Type-I and 24 Type-II AGNs, amounting to ∼4 per cent of our sample, similar to the fraction reported by previous explorations in the same redshift range. We compare the integrated properties of the ionized and molecular gas, and stellar population of AGN hosts and their non-active counterparts, combining them with morphological information. The AGN hosts are found in transitory parts (i.e. green-valley) in almost all analysed properties which present bimodal distributions (i.e. a region where reside star-forming galaxies and another with quiescent/retired ones). Regarding morphology, we find AGN hosts among the most massive galaxies, with enhanced central stellar-mass surface density in comparison to the average population at each morphological type. Moreover, their distribution peaks at the Sab-Sb classes and none are found among very late-type galaxies (>Scd). Finally, we inspect how the AGN could act in their hosts regarding the quenching of star-formation. The main role of the AGN in the quenching process appears to be the removal (or heating) of molecular gas, rather than an additional suppression of the already observed decrease of the star-formation efficiency from late-to-early type galaxies.

scholarly journals Serendipitous discovery of an “ALMA-only” galaxy at 5 < z < 6 in an ALMA 3-mm survey

2019 ◽  
Vol 15 (S352) ◽  
pp. 194-198
Author(s):  
Christina C. Williams
Keyword(s):  
Star Formation ◽  
Energy Distribution ◽  
Star Formation Rate ◽  
High Redshift ◽  
Spectral Energy Distribution ◽  
Formation Rate ◽  
Spectral Energy ◽  
Large Contribution ◽  
Massive Galaxies ◽  
Multi Wavelength

AbstractWe discuss the serendipitous discovery of a dusty high-redshift galaxy in a small (8 arcmin2) ALMA 3-mm survey Williams et al. (2019). The galaxy was previously unknown and is absent from existing multi-wavelength catalogs (“ALMA-only”). Using the ALMA position as prior, we perform forced deblended photometry to constrain its spectral energy distribution. The spectral energy distribution is well described by a massive (M* = 1010.8 M⊙) and highly obscured (AV ∼ 4) galaxy at redshift z = 5.5 ± 1.1 with star formation rate ∼ 300 M⊙yr−1. Our small survey area implies an uncertain but large contribution to the cosmic star formation rate density, similar to the contribution from all ultraviolet-selected galaxies combined at this redshift. This galaxy likely traces an abundant population of massive galaxies absent from current samples of infrared-selected or sub-millimeter galaxies, but with larger space densities, higher duty cycles, and significant contribution to the cosmic star-formation rate and stellar mass densities.

scholarly journals THE DISTRIBUTION OF SATELLITES AROUND MASSIVE GALAXIES AT 1

2014 ◽  
Vol 792 (2) ◽  
pp. 103 ◽  
Author(s):  
Lalitwadee Kawinwanichakij ◽  
Casey Papovich ◽  
Ryan F. Quadri ◽  
Kim-Vy H. Tran ◽  
Lee R. Spitler ◽  
...  
Keyword(s):  
Star Formation ◽  
Massive Galaxies ◽  
Star Formation Activity

scholarly journals Evolution of Massive Galaxy Structural Properties and Sizes via Star Formation

2012 ◽  
Vol 10 (H16) ◽  
pp. 128-128
Author(s):  
Jamie R. Ownsworth ◽  
Christopher J. Conselice ◽  
Alice Mortlock ◽  
William G. Hartley ◽  
Fernando Buitrago
Keyword(s):  
Star Formation ◽  
Rest Frame ◽  
High Redshift ◽  
Formation Rate ◽  
Stellar Mass ◽  
Massive Galaxies ◽  
Mass Profile ◽  
Individual Galaxy ◽  
Mass Profiles

We investigate the resolved star formation properties of a sample of 45 massive galaxies (M* > 1011 M⊙) within a redshift range of 1.5 ⩽ z ⩽ 3 detected in the GOODS NICMOS Survey (Conselice et al. 2011), a HST H160-band imaging program. We derive the star formation rate as a function of radius using rest frame UV data from deep z850 ACS imaging. The star formation present at high redshift is then extrapolated to z = 0, and we examine the stellar mass produced in individual regions within each galaxy. We also construct new stellar mass profiles of the in situ stellar mass at high redshift from Sérsic fits to rest-frame optical, H160-band, data. We combine the two stellar mass profiles to produce an evolved stellar mass profile. We then fit a new Sérsic profile to the evolved profile, from which we examine what effect the resulting stellar mass distribution added via star formation has on the structure and size of each individual galaxy.

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