scholarly journals An older, more quiescent universe from panchromatic SED fitting of the 3D-HST survey

2019 ◽  
Vol 15 (S352) ◽  
pp. 99-102
Author(s):  
Joel Leja ◽  
Benjamin D. Johnson ◽  
Charlie Conroy ◽  
Pieter van Dokkum ◽  
Joshua S. Speagle ◽  
...  
Keyword(s):  
Star Formation ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Complex Scaling ◽  
Physical Systems ◽  
Scaling Relationships ◽  
Highly Correlated ◽  
Bayesian Inference Framework ◽  
Stellar Masses ◽  
Star Formation Histories

AbstractGalaxies are complicated physical systems which obey complex scaling relationships; as a result, properties measured from broadband photometry are often highly correlated, degenerate, or both. Therefore, the accuracy of basic properties like stellar masses and star formation rates (SFRs) depend on the accuracy of many second-order galaxy properties, including star formation histories (SFHs), stellar metallicities, dust properties, and many others. Here, we re-assess measurements of galaxy stellar masses and SFRs using a 14-parameter physical model built in the Prospector Bayesian inference framework. We find that galaxies are ∼0.2 dex more massive and have ∼0.2 dex lower star formation rates than classic measurements. These measurements lower the observed cosmic star formation rate density and increase the observed buildup of stellar mass, finally bringing these two metrics into agreement at the factor-of-two level at 0.5 < z < 2.5.

scholarly journals Effect of the environment on star formation activity and stellar mass for star-forming galaxies in the COSMOS field

2020 ◽  
Vol 499 (1) ◽  
pp. 948-956
Author(s):  
S M Randriamampandry ◽  
M Vaccari ◽  
K M Hess
Keyword(s):  
Star Formation ◽  
Main Sequence ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Cosmic Time ◽  
Stellar Mass ◽  
Star Forming ◽  
Galaxy Environment ◽  
Stellar Masses ◽  
The Relationship

ABSTRACT We investigate the relationship between the environment and the galaxy main sequence (the relationship between stellar mass and star formation rate), as well as the relationship between the environment and radio luminosity ($P_{\rm 1.4\, GHz}$), to shed new light on the effects of the environment on galaxies. We use the VLA-COSMOS 3-GHz catalogue, which consists of star-forming galaxies and quiescent galaxies (active galactic nuclei) in three different environments (field, filament, cluster) and for three different galaxy types (satellite, central, isolated). We perform for the first time a comparative analysis of the distribution of star-forming galaxies with respect to the main-sequence consensus region from the literature, taking into account galaxy environment and using radio observations at 0.1 ≤ z ≤ 1.2. Our results corroborate that the star formation rate is declining with cosmic time, which is consistent with the literature. We find that the slope of the main sequence for different z and M* bins is shallower than the main-sequence consensus, with a gradual evolution towards higher redshift bins, irrespective of environment. We see no trends for star formation rate in either environment or galaxy type, given the large errors. In addition, we note that the environment does not seem to be the cause of the flattening of the main sequence at high stellar masses for our sample.

scholarly journals Spectral synthesis of stellar populations in the 3D era: The CALIFA experience

2014 ◽  
Vol 10 (S309) ◽  
pp. 93-98
Author(s):  
R. Cid Fernandes ◽  
E. A. D. Lacerda ◽  
R. M. González Delgado ◽  
N. Vale Asari ◽  
R. García-Benito ◽  
...  
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Spectral Synthesis ◽  
Mass Density ◽  
Formation Rate ◽  
Stellar Populations ◽  
Data Cubes ◽  
The Mean ◽  
Stellar Masses ◽  
Star Formation Histories

AbstractMethods to recover the fossil record of galaxy evolution encoded in their optical spectra have been instrumental in processing the avalanche of data from mega-surveys along the last decade, effectively transforming observed spectra onto a long and rich list of physical properties: from stellar masses and mean ages to full star formation histories. This promoted progress in our understanding of galaxies as a whole. Yet, the lack of spatial resolution introduces undesirable aperture effects, and hampers advances on the internal physics of galaxies. This is now changing with 3D surveys. The mapping of stellar populations in data-cubes allows us to figure what comes from where, unscrambling information previously available only in integrated form. This contribution uses our starlight-based analysis of 300 CALIFA galaxies to illustrate the power of spectral synthesis applied to data-cubes. The selected results highlighted here include: (a) The evolution of the mass-metallicity and mass-density-metallicity relations, as traced by the mean stellar metallicity. (b) A comparison of star formation rates obtained from Hα to those derived from full spectral fits. (c) The relation between star formation rate and dust optical depth within galaxies, which turns out to mimic the Schmidt-Kennicutt law. (d) PCA tomography experiments.

Star formation in dwarf galaxies in the ELAIS N1 field

2018 ◽  
Vol 14 (S344) ◽  
pp. 292-295
Author(s):  
Tímea O. Kovács ◽  
Denis Burgarella ◽  
L. Viktor Tóth
Keyword(s):  
Star Formation ◽  
Dwarf Galaxies ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Spectral Energy ◽  
Energy Distributions ◽  
Normal Galaxies ◽  
Radiation Data ◽  
Order Of Magnitude ◽  
Stellar Masses

AbstractWe estimated several parameters of dwarf galaxies, including their star formation rate and dust mass, and compared them with galaxies with larger stellar masses.We have chosen dwarf galaxies in the ELAIS N1 field, and fitted their Spectral Energy Distributions (SED). We used data from the new Herschel SPIRE and PACS Point Source catalogues to constrain the infrared radiation. Data available in VIZIER from multiple surveys have also been used.We determined that the star formation rate (SFR), M* and Mdust is one order of magnitude lower in dwarf galaxies compared to galaxies with larger stellar masses. However, the starburtiness was higher in the dwarf galaxies. They also had lower redshifts than normal galaxies, so we compared them to a subsample of normal galaxies with lower redshifts. The dust masses and SFRs of the dwarf galaxies were slightly lower, but their starburtiness was higher.

scholarly journals Rejuvenated galaxies with very old bulges at the origin of the bending of the main sequence and of the ‘green valley’

2019 ◽  
Vol 489 (1) ◽  
pp. 1265-1290 ◽  
Author(s):  
Chiara Mancini ◽  
Emanuele Daddi ◽  
Stéphanie Juneau ◽  
Alvio Renzini ◽  
Giulia Rodighiero ◽  
...  
Keyword(s):  
Star Formation ◽  
Main Sequence ◽  
Formation Rate ◽  
Very Old ◽  
Massive Galaxies ◽  
Star Forming ◽  
Late Event ◽  
Age Of The Universe ◽  
Stellar Masses ◽  
Star Formation Histories

ABSTRACT We investigate the nature of star-forming galaxies with reduced specific star formation rate (sSFR) and high stellar masses, those ‘green valley’ objects that seemingly cause a reported bending, or flattening, of the star-forming main sequence. The fact that such objects host large bulges recently led some to suggest that the internal formation of bulges was a late event that induced the sSFRs of massive galaxies to drop in a slow downfall, and thus the main sequence to bend. We have studied in detail a sample of 10 galaxies at 0.45 &lt; z &lt; 1 with secure SFR from Herschel, deep Keck optical spectroscopy, and HST imaging from CANDELS allowing us to perform multiwavelength bulge to disc decomposition, and to derive star formation histories for the separated bulge and disc components. We find that the bulges hosted in these systems below main sequence are virtually all maximally old, with ages approaching the age of the Universe at the time of observation, while discs are young (〈 T50〉 ∼ 1.5 Gyr). We conclude that, at least based on our sample, the bending of the main sequence is, for a major part, due to rejuvenation, and we disfavour mechanisms that postulate the internal formation of bulges at late times. The very old stellar ages of our bulges suggest a number density of early-type galaxies at z = 1–3 higher than actually observed. If confirmed, this might represent one of the first direct validations of hierarchical assembly of bulges at high redshifts.

scholarly journals Lessons from comparisons between the nuclear region of the Milky Way and those in nearby spirals

2013 ◽  
Vol 9 (S303) ◽  
pp. 61-65
Author(s):  
John S. Gallagher ◽  
Tova M. Yoast-Hull ◽  
Ellen G. Zweibel
Keyword(s):  
Star Formation ◽  
Milky Way ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Molecular Gas ◽  
Nuclear Region ◽  
Stellar Content ◽  
Nuclear Regions ◽  
Stellar Masses

AbstractThe Milky Way appears as a typical barred spiral, and comparisons can be made between its nuclear region and those of structurally similar nearby spirals. Maffei 2, M83, IC 342 and NGC 253 are nearby systems whose nuclear region properties contrast with those of the Milky Way. Stellar masses derived from NIR photometery, molecular gas masses and star formation rates allow us to assess the evolutionary states of this set of nuclear regions. These data suggest similarities between nuclear regions in terms of their stellar content while highlighting significant differences in current star formation rates. In particular current star formation rates appear to cover a larger range than expected based on the molecular gas masses. This behavior is consistent with nuclear region star formation experiencing episodic variations. Under this hypothesis the Milky Way's nuclear region currently may be in a low star formation rate phase.

scholarly journals The Metal Abundances across Cosmic Time (MACT) Survey. III – The relationship between stellar mass and star formation rate in extremely low-mass galaxies

2020 ◽  
Vol 501 (2) ◽  
pp. 2231-2249 ◽  
Author(s):  
Kaitlyn Shin ◽  
Chun Ly ◽  
Matthew A Malkan ◽  
Sangeeta Malhotra ◽  
Mithi de los Reyes ◽  
...  
Keyword(s):  
Star Formation ◽  
Near Infrared ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Cosmic Time ◽  
Stellar Mass ◽  
Star Forming ◽  
Dependent Relation ◽  
Photometric Measurements ◽  
Stellar Masses

ABSTRACT Extragalactic studies have demonstrated that there is a moderately tight (≈0.3 dex) relationship between galaxy stellar mass (M⋆) and star formation rate (SFR) that holds for star-forming galaxies at M⋆ ∼ 3 × 108–1011 M⊙, i.e. the ‘star formation main sequence’. However, it has yet to be determined whether such a relationship extends to even lower mass galaxies, particularly at intermediate or higher redshifts. We present new results using observations for 714 narrow-band H α-selected galaxies with stellar masses between 106 and 1010 M⊙ (average of 108.2 M⊙) at z ≈ 0.07–0.5. These galaxies have sensitive ultraviolet (UV) to near-infrared photometric measurements and optical spectroscopy. The latter allows us to correct our H α SFRs for dust attenuation using Balmer decrements. Our study reveals that: (1) for low-SFR galaxies, our H α SFRs systematically underpredict compared to far-UV measurements, consistent with other studies; (2) at a given stellar mass (≈108 M⊙), log (specific SFR) evolves as A log (1 + z) with A = 5.26 ± 0.75, and on average, specific SFR increases with decreasing stellar mass; (3) the SFR–M⋆ relation holds for galaxies down to ∼106 M⊙ (∼1.5 dex below previous studies), and over lookback times of up to 5 Gyr, follows a redshift-dependent relation of log (SFR) ∝ α log (M⋆/M⊙) + β z with α = 0.60 ± 0.01 and β = 1.86 ± 0.07; and (4) the observed dispersion in the SFR–M⋆ relation at low stellar masses is ≈0.3 dex. Accounting for survey selection effects using simulated galaxies, we estimate that the true dispersion is ≈0.5 dex.

scholarly journals Galaxies in the first billion years: implications for re-ionization and the star formation history at z>6

2006 ◽  
Vol 2 (14) ◽  
pp. 248-248
Author(s):  
Andrew J. Bunker ◽  
Elizabeth R. Stanway ◽  
Laurence P. Eyles ◽  
Richard S. Ellis ◽  
Richard G. McMahon ◽  
...  
Keyword(s):  
Star Formation ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Stellar Populations ◽  
Star Formation History ◽  
Star Forming ◽  
Formation History ◽  
Stellar Masses ◽  
The Universe ◽  
Selection Of

AbstractWe discuss the selection of star-forming galaxies at z≃6 through the Lyman-break technique. Spitzer imaging implies many of these contain older stellar populations (>200Myr) which produce detectable Balmer breaks. The ages and stellar masses (∼1010M⊙) imply that the star formation rate density at earlier epochs may have been significantly higher than at z≃6, and might have played a key role in re-ionizing the universe.

scholarly journals ALMA twenty-six arcmin2 survey of GOODS-S at one millimeter (ASAGAO): Millimeter properties of stellar mass selected galaxies

2020 ◽  
Vol 72 (4) ◽  
Author(s):  
Yuki Yamaguchi ◽  
Kotaro Kohno ◽  
Bunyo Hatsukade ◽  
Tao Wang ◽  
Yuki Yoshimura ◽  
...  
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Star Formation Rate ◽  
Signal To Noise Ratio ◽  
Formation Rate ◽  
Stellar Mass ◽  
Star Forming ◽  
Deep Survey ◽  
Stellar Masses ◽  
Relationship Of

Abstract We make use of the ALMA twenty-Six Arcmin2 survey of GOODS-S At One-millimeter (ASAGAO), deep 1.2 mm continuum observations of a 26-arcmin2 region in the Great Observatories Origins Deep Survey-South (GOODS-S) obtained with Atacama Large Millimeter/sub-millimeter Array (ALMA), to probe dust-enshrouded star formation in K-band selected (i.e., stellar mass selected) galaxies, which are drawn from the FourStar Galaxy Evolution Survey (ZFOURGE) catalog. Based on the ASAGAO combined map, which was created by combining ASAGAO and ALMA archival data in the GOODS-South field, we find that 24 ZFOURGE sources have 1.2 mm counterparts with a signal-to-noise ratio &gt;4.5 (1σ ≃ 30–70 μJy beam−1 at 1.2 mm). Their median redshift is estimated to be $z$median = 2.38 ± 0.14. They generally follow the tight relationship of the stellar mass versus star formation rate (i.e., the main sequence of star-forming galaxies). ALMA-detected ZFOURGE sources exhibit systematically larger infrared (IR) excess (IRX ≡ LIR/LUV) compared to ZFOURGE galaxies without ALMA detections even though they have similar redshifts, stellar masses, and star formation rates. This implies the consensus stellar-mass versus IRX relation, which is known to be tight among rest-frame-ultraviolet-selected galaxies, cannot fully predict the ALMA detectability of stellar-mass-selected galaxies. We find that ALMA-detected ZFOURGE sources are the main contributors to the cosmic IR star formation rate density at $z$ = 2–3.

scholarly journals Evolution of star formation rate–density relation over cosmic time in a simulated universe: the observed reversal reproduced

2019 ◽  
Vol 489 (1) ◽  
pp. 339-348 ◽  
Author(s):  
Ho Seong Hwang ◽  
Jihye Shin ◽  
Hyunmi Song
Keyword(s):  
Star Formation ◽  
Star Formation Rate ◽  
Local Density ◽  
Formation Rate ◽  
Cosmic Time ◽  
Galaxy Cluster ◽  
Star Forming ◽  
Hydrodynamical Simulation ◽  
Density Relation ◽  
Stellar Masses

ABSTRACT We use the IllustrisTNG cosmological hydrodynamical simulation to study the evolution of star formation rate (SFR)–density relation over cosmic time. We construct several samples of galaxies at different redshifts from z = 2.0 to z = 0.0, which have the same comoving number density. The SFR of galaxies decreases with local density at z = 0.0, but its dependence on local density becomes weaker with redshift. At z ≳ 1.0, the SFR of galaxies increases with local density (reversal of the SFR–density relation), and its dependence becomes stronger with redshift. This change of SFR–density relation with redshift still remains even when fixing the stellar masses of galaxies. The dependence of SFR on the distance to a galaxy cluster also shows a change with redshift in a way similar to the case based on local density, but the reversal happens at a higher redshift, z ∼ 1.5, in clusters. On the other hand, the molecular gas fraction always decreases with local density regardless of redshift at z = 0.0–2.0 even though the dependence becomes weaker when we fix the stellar mass. Our study demonstrates that the observed reversal of the SFR–density relation at z ≳ 1.0 can be successfully reproduced in cosmological simulations. Our results are consistent with the idea that massive, star-forming galaxies are strongly clustered at high redshifts, forming larger structures. These galaxies then consume their gas faster than those in low-density regions through frequent interactions with other galaxies, ending up being quiescent in the local universe.

scholarly journals Seeking footprints of the primeval Universe in dwarf galaxies

2012 ◽  
Vol 10 (H16) ◽  
pp. 273-274
Author(s):  
Sebastian L. Hidalgo ◽  
Keyword(s):  
Star Formation ◽  
Dwarf Galaxies ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Stellar Content ◽  
Time Intervals ◽  
Fundamental Properties ◽  
Star Formation Histories

AbstractWe present the star formation histories (SFHs) of four isolated dwarf galaxies, Cetus, Tucana, LGS-3, and Phoenix, as a function of galactocentric radius. Our results suggest that beyond some distance from the center, there are no significative differences in fundamental properties of these galaxies, such as the star formation rate (SFR) or age-metallicity relation (AMR). The stellar content of this region would be composed of old (≳ 10.5 Gyr) metal-poor stars only. In the innermost regions, dwarf galaxies appear to have formed stars during time intervals which duration varies from galaxy to galaxy. This extended star formation produces the dichotomy between dwarf spheroidal (dSph) and dwarf Transition (dTr) galaxy types.

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