scholarly journals xGASS: cold gas content and quenching in galaxies below the star-forming main sequence

2020 ◽  
Vol 493 (2) ◽  
pp. 1982-1995 ◽  
Author(s):  
Steven Janowiecki ◽  
Barbara Catinella ◽  
Luca Cortese ◽  
Amelie Saintonge ◽  
Jing Wang
Keyword(s):  
Star Formation ◽  
Main Sequence ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Gas Content ◽  
Gas Reservoirs ◽  
Star Forming ◽  
Correct Model ◽  
Gas Measurements ◽  
Cold Gas

ABSTRACT We use H i and H2 global gas measurements of galaxies from xGASS and xCOLD GASS to investigate quenching paths of galaxies below the Star forming main sequence (SFMS). We show that the population of galaxies below the SFMS is not a 1:1 match with the population of galaxies below the H i and H2 gas fraction scaling relations. Some galaxies in the transition zone (TZ) 1σ below the SFMS can be as H i-rich as those in the SFMS, and have on average longer gas depletion time-scales. We find evidence for environmental quenching of satellites, but central galaxies in the TZ defy simple quenching pathways. Some of these so-called ‘quenched’ galaxies may still have significant gas reservoirs and be unlikely to deplete them any time soon. As such, a correct model of galaxy quenching cannot be inferred with star formation rate (or other optical observables) alone, but must include observations of the cold gas. We also find that internal structure (particularly, the spatial distribution of old and young stellar populations) plays a significant role in regulating the star formation of gas-rich isolated TZ galaxies, suggesting the importance of bulges in their evolution.

scholarly journals Significance of bar quenching in the global quenching of star formation

2019 ◽  
Vol 628 ◽  
pp. A24 ◽  
Author(s):  
K. George ◽  
S. Subramanian ◽  
K. T. Paul
Keyword(s):  
Star Formation ◽  
Main Sequence ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Stellar Mass ◽  
Gas Content ◽  
Disk Galaxies ◽  
Local Universe ◽  
Star Forming ◽  
Barred Galaxies

The suppression of star formation in the inner kiloparsec regions of barred disk galaxies due to the action of bars is known as bar quenching. We investigate here the significance of bar quenching in the global quenching of star formation in the barred galaxies and their transformation to passive galaxies in the local Universe. We do this by measuring the offset of quenched barred galaxies from star-forming main sequence galaxies in the star formation rate-stellar mass plane and comparing it with the length of the bar, which is considered as a proxy of bar quenching. We constructed the star formation rate-stellar mass plane of 2885 local Universe face-on strong barred disk galaxies (z <  0.06) identified by Galaxy Zoo. The barred disk galaxies studied here fall on the star formation main sequence relation with a significant scatter for galaxies above stellar mass 1010.2M⊙. We found that 34.97% galaxies are within the intrinsic scatter (0.3 dex) of the main sequence relation, with a starburst population of 10.78% (above the 0.3 dex) and a quenched population of 54.25% (below the −0.3 dex) of the total barred disk galaxies in our sample. Significant neutral hydrogen (MHI > 109M⊙ with log MHI/M⋆ ∼ −1.0 to −0.5) is detected in the quenched barred galaxies with a similar gas content to that of the star-forming barred galaxies. We found that the offset of the quenched barred galaxies from the main sequence relation is not dependent on the length of the stellar bar. This implies that the bar quenching may not contribute significantly to the global quenching of star formation in barred galaxies. However, this observed result could also be due to other factors such as the dissolution of bars over time after star formation quenching, the effect of other quenching processes acting simultaneously, and/or the effects of environment.

scholarly journals On the relationship between gas content, star formation, and global H i asymmetry of galaxies on the star-forming main-sequence

2021 ◽  
Vol 504 (2) ◽  
pp. 1989-1998
Author(s):  
Adam B Watts ◽  
Barbara Catinella ◽  
Luca Cortese ◽  
Chris Power ◽  
Sara L Ellison
Keyword(s):  
Star Formation ◽  
Atomic Hydrogen ◽  
Main Sequence ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Stellar Mass ◽  
Gas Content ◽  
Merger Activity ◽  
Star Forming ◽  
The Relationship

ABSTRACT Observations have revealed that disturbances in the cold neutral atomic hydrogen (H i) in galaxies are ubiquitous, but the reasons for these disturbances remain unclear. While some studies suggest that asymmetries in integrated H i spectra (global H i asymmetry) are higher in H i-rich systems, others claim that they are preferentially found in H i-poor galaxies. In this work, we utilize the Arecibo Legacy Fast ALFA (ALFALFA) and extended GALEX Arecibo SDSS Survey (xGASS) surveys, plus a sample of post-merger galaxies, to clarify the link between global H i asymmetry and the gas properties of galaxies. Focusing on star-forming galaxies in ALFALFA, we find that elevated global H i asymmetry is not associated with a change in the H i content of a galaxy, and that only the galaxies with the highest global H i asymmetry show a small increase in specific star formation rate (sSFR). However, we show that the lack of a trend with H i content is because ALFALFA misses the ‘gas-poor’ tail of the star-forming main-sequence. Using xGASS to obtain a sample of star-forming galaxies that is representative in both sSFR and H i content, we find that global H i asymmetric galaxies are typically more gas-poor than symmetric ones at fixed stellar mass, with no change in sSFR. Our results highlight the complexity of the connection between galaxy properties and global H i asymmetry. This is further confirmed by the fact that even post-merger galaxies show both symmetric and asymmetric H i spectra, demonstrating that merger activity does not always lead to an asymmetric global H i spectrum.

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 PHIBSS2: survey design and z = 0.5 – 0.8 results

2019 ◽  
Vol 622 ◽  
pp. A105 ◽  
Author(s):  
J. Freundlich ◽  
F. Combes ◽  
L. J. Tacconi ◽  
R. Genzel ◽  
S. Garcia-Burillo ◽  
...  
Keyword(s):  
Star Formation ◽  
Survey Design ◽  
Formation Rate ◽  
Sample Selection ◽  
Stellar Mass ◽  
Gas Content ◽  
Molecular Gas ◽  
Star Forming ◽  
Gas Measurements ◽  
Deep Fields

Following the success of the Plateau de Bure high-z Blue Sequence Survey (PHIBSS), we present the PHIBSS2 legacy program, a survey of the molecular gas properties of star-forming galaxies on and around the star-formation main sequence (MS) at different redshifts using IRAM’s NOrthern Extended Millimeter Array (NOEMA). This survey significantly extends the existing sample of star-forming galaxies with CO molecular gas measurements, probing the peak epoch of star formation (z = 1 − 1.6) as well as its building-up (z = 2 − 3) and winding-down (z = 0.5 − 0.8) phases. The targets are drawn from the well-studied GOODS, COSMOS, and AEGIS cosmological deep fields and uniformly sample the MS in the stellar mass (M⋆) – star formation rate (SFR) plane with log(M⋆/M⊙) = 10 − 11.8 and SFR = 3.5 − 500 M⊙ yr−1 without morphological selection, thus providing a statistically meaningful census of star-forming galaxies at different epochs. We describe the survey strategy and sample selection before focusing on the results obtained at redshift z = 0.5 − 0.8, where we report 60 CO(2-1) detections out of 61 targets. We determine molecular gas masses between 2 × 109 and 5 × 1010 M⊙ and separately obtain disc sizes and bulge-to-total (B/T) luminosity ratios from HST I-band images. The median molecular gas-to-stellar mass ratio μgas∼ = 0.28 ± 0.04, gas fraction fgas∼ = 0.22 ± 0.02, and depletion time $ \widetilde{t_{\mathrm{depl}}} = 0.84 \pm 0.07\,\mathrm{Gyr} $ as well as their dependence with stellar mass and offset from the MS follow published scaling relations for a much larger sample of galaxies spanning a significantly wider range of redshifts, the cosmic evolution of the SFR being mainly driven by that of the molecular gas fraction. The galaxy-averaged molecular Kennicutt–Schmidt (KS) relation between molecular gas and SFR surface densities is strikingly linear, pointing towards similar star formation timescales within galaxies at any given epoch. In terms of morphology, the molecular gas content, the SFR, the disc stellar mass, and the disc molecular gas fraction do not seem to correlate with B/T and the stellar surface density, which suggests an ongoing supply of fresh molecular gas to compensate for the build-up of the bulge. Our measurements do not yield any significant variation of the depletion time with B/T and hence no strong evidence for morphological quenching within the scatter of the MS.

scholarly journals The Iκεα model of feedback-regulated galaxy formation

2019 ◽  
Author(s):  
Mahavir Sharma ◽  
Tom Theuns
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Self Regulation ◽  
Mass Function ◽  
Stellar Mass ◽  
Gas Content ◽  
Dark Matter Halo ◽  
Star Forming

Abstract We present the Iκεα model of galaxy formation, in which a galaxy’s star formation rate is set by the balance between energy injected by feedback from massive stars and energy lost by the deepening of the potential of its host dark matter halo due to cosmological accretion. Such a balance is secularly stable provided that the star formation rate increases with the pressure in the star forming gas. The Iκεα model has four parameters that together control the feedback from star formation and the cosmological accretion rate onto a halo. Iκεα reproduces accurately the star formation rate as a function of halo mass and redshift in the eagle hydrodynamical simulation, even when all four parameters are held constant. It predicts the emergence of a star forming main sequence along which the specific star formation rate depends weakly on stellar mass with an amplitude that increases rapidly with redshift. We briefly discuss the emerging mass-metallicity relation, the evolution of the galaxy stellar mass function, and an extension of the model that includes feedback from active galactic nuclei (AGN). These self-regulation results are independent of the star formation law and the galaxy’s gas content. Instead, star forming galaxies are shaped by the balance between stellar feedback and cosmological accretion, with accurately accounting for energy losses associated with feedback a crucial ingredient.

scholarly journals The impact of quenching on galaxy profiles in the simba simulation

2020 ◽  
Vol 494 (4) ◽  
pp. 6053-6071 ◽  
Author(s):  
Sarah Appleby ◽  
Romeel Davé ◽  
Katarina Kraljic ◽  
Daniel Anglés-Alcázar ◽  
Desika Narayanan
Keyword(s):  
Star Formation ◽  
Star Formation Rate ◽  
High Redshift ◽  
Formation Rate ◽  
Gas Content ◽  
X Ray ◽  
Star Forming ◽  
Numerical Resolution ◽  
Radial Profiles ◽  
The Impact

ABSTRACT We study specific star formation rate (sSFR) and gas profiles of star-forming (SF) and green valley (GV) galaxies in the simba cosmological hydrodynamic simulation. SF galaxy half-light radii (Rhalf) at z = 0 and their evolution (∝(1 + z)−0.78) agree with observations. Passive galaxy Rhalf agree with observations at high redshift, but by z = 0 are too large, owing to numerical heating. We compare simbaz = 0 sSFR radial profiles for SF and GV galaxies to observations. simba shows strong central depressions in star formation rate (SFR), sSFR, and gas fraction in GV galaxies and massive SF systems, qualitatively as observed, owing to black hole X-ray feedback, which pushes central gas outwards. Turning off X-ray feedback leads to centrally peaked sSFR profiles as in other simulations. In conflict with observations, simba yields GV galaxies with strongly dropping sSFR profiles beyond ≳Rhalf, regardless of active galactic nucleus feedback. The central depression owes to lowering molecular gas content; the drop in the outskirts owes to reduced star formation efficiency. simba’s satellites have higher central sSFR and lower outskirts sSFR than centrals, in qualitative agreement with observations. At z = 2, simba does not show central depressions in massive SF galaxies, suggesting simba’s X-ray feedback should be more active at high-z. High-resolution tests indicate central sSFR suppression is not sensitive to numerical resolution. Reproducing the central sSFR depression in z = 0 GV galaxies represents a unique success of simba. The remaining discrepancies highlight the importance of SFR and gas profiles in constraining quenching mechanisms.

scholarly journals Dark Matter Halos and the Main Sequence of Starforming Galaxies

2015 ◽  
Vol 11 (S319) ◽  
pp. 1-1
Author(s):  
Hervé Aussel ◽  
Sébastien Peirani ◽  
Laurent Vigroux
Keyword(s):  
Dark Matter ◽  
Star Formation ◽  
Numerical Simulations ◽  
Power Law ◽  
Main Sequence ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Stellar Mass ◽  
Dark Matter Halos ◽  
Star Forming

AbstractWe investigate why hydrodynamical numerical simulations have difficulties (Weinmann et al. 2011) in reproducing the Main Sequence (MS) of star-forming galaxies, i.e. the fact that galaxies forming stars lie on a tight power law sequence in the stellar mass (M*), star formation rate (SFR) plane (Schreiber et al. 2015). Instead of trying to improve the agreement of simulations with the observations by modifying the subgrid recipes of baryons, we take here a step back to check whether the accretion onto dark matter halos is consistent with the existence of the main sequence of star forming galaxies.

scholarly journals Star formation history: secular processes in “main sequence“ galaxies versus merger-driven starbursts

2012 ◽  
Vol 10 (H16) ◽  
pp. 374-374
Author(s):  
Matthieu Bethermin
Keyword(s):  
Star Formation ◽  
Main Sequence ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Mass Function ◽  
Stellar Mass ◽  
Star Formation History ◽  
Star Forming ◽  
Gaussian Decomposition ◽  
Number Counts

AbstractSome recent works indicate that most star-forming galaxies follow a main sequence in the SFR-stellar mass plane with a surprisingly low scatter of ≈0.2 dex, suggesting that the star formation in these objects is driven by secular processes. Nevertheless, Herschel identified a population of starbursting galaxies, probably triggered by mergers, which display a large excess of specific star formation rate (sSFR=SFR/Mstar) compared to the main sequence. We will present a new set of models for the contribution of these two populations to the IR/sub-mm luminosity function, but also to source counts selected at various wavelengths.Our model is based on the stellar mass function of star-forming galaxies, the distribution of sSFR measured at z=2 and its double-Gaussian decomposition, and the observed evolution of the main sequence in the sSFR-Mass plane as a function of redshift. We found that the non-Schechter bright-end of the LF is due to the starbursting galaxies, which represent only 4% in number density and 15% in luminosity density. This fraction of starbursts is remarkably constant with the redshift at 0<z<2, contrary to naive expectation from hierarchical merging. It thus suggests that the majority of stars in the Universe were formed through secular processes. We will then discuss the contribution of starbursting and main sequence galaxies to the number counts and the selection effects towards starbursts sources for various flux-limited IR/sub-mm samples.We will also present studies of the clustering properties of the main sequence and starburst galaxies at z 2. These measurements suggest strong links between star formation rate, stellar mass and halo mass in the main sequence galaxies. In addition, we will present some clues suggesting that main sequence and starbursting galaxies follows the same M*-Mhalo relation.”

scholarly journals Molecular gas content in typical L* galaxies at z ∼ 1.5 − 3

2014 ◽  
Vol 10 (S309) ◽  
pp. 285-286
Author(s):  
Miroslava Dessauges-Zavadsky ◽  
Michel Zamojski ◽  
Daniel Schaerer ◽  
Françoise Combes ◽  
Eiichi Egami ◽  
...  
Keyword(s):  
Star Formation ◽  
Formation Rate ◽  
Stellar Mass ◽  
Gas Content ◽  
Physical Parameters ◽  
Molecular Gas ◽  
Star Forming ◽  
Large Spread ◽  
Gas Measurements ◽  
Formation Efficiency

AbstractTo extend the molecular gas measurements to typical L* star-forming galaxies (SFGs) at z ∼ 1.5 − 3, we have observed CO emission for five strongly-lensed galaxies selected from the Herschel Lensing Survey. The combined sample of our L* SFGs with CO-detected SFGs at z >1 from the literature shows a large spread in star formation efficiency (SFE). We find that this spread in SFE is due to variations of several physical parameters, primarily the specific star formation rate, but also stellar mass and redshift. An increase of the molecular gas fraction (fgas) is observed from z ∼ 0.2 to z ∼ 1.2, followed by a quasi non-evolution toward higher redshifts, as found in earlier studies. We provide the first measure of fgas of z >1 SFGs at the low-stellar mass end between 109.4 < M∗/M⊙ < 109.9, which shows a clear fgas upturn.

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