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 ◽  
...  

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.

2020 ◽  
Vol 499 (1) ◽  
pp. 948-956
Author(s):  
S M Randriamampandry ◽  
M Vaccari ◽  
K M Hess

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.


2016 ◽  
Vol 11 (S321) ◽  
pp. 273-273
Author(s):  
C. Catalán-Torrecilla ◽  
A. Gil de Paz ◽  
A. Castillo-Morales ◽  
J. Méndez-Abreu ◽  
S. Pascual ◽  
...  

AbstractExploring the spatial distribution of the star formation rate (SFR) in nearby galaxies is essential to understand their evolution through cosmic time. With this aim in mind, we use a representative sample that contains a variety of morphological types, the CALIFA Integral Field Spectroscopy (IFS) sample. Previous to this work, we have verified that our extinction-corrected Hα measurements successfully reproduce the values derived from other SFR tracers such as Hαobs + IR or UVobs + IR (Catalán-Torrecilla et al. 2015).Now, we go one step further applying 2-dimensional photometric decompositions (Méndez-Abreu et al. (2008), Méndez-Abreu et al. (2014)) over these datacubes. This method allows us to obtain the amount of SFR in the central part (bulge or nuclear source), the bar and the disk, separately. First, we determine the light coming from each component as the ratio between the luminosity in every component (bulge, bar or disk) and the total luminosity of the galaxy. Then, for each galaxy we multiply the IFS datacubes by these previous factors to recover the luminosity in each component. Finally, we derive the spectrum associated to each galaxy component integrating the spatial information in the weighted datacube using an elliptical aperture covering the whole galaxy.2D photometric decomposition applied over 3D datacubes will give us a more detailed understanding of the role that disks play in more massive galaxies. Knowing if the disks in more massive SF galaxies have on average a lower or higher level of star formation activity and how these results are affected by the presence of nuclear bars are still open questions that we can now solve. We describe the behavior of these components in the SFR vs. stellar mass diagram. In particular, we highlight the role of the disks and their contribution to both the integrated SFR for the whole galaxy and the SFR in the disk at different stellar masses in the SFR vs. stellar mass diagram together with their relative position to the star forming Main Sequence.


2020 ◽  
Vol 72 (4) ◽  
Author(s):  
Yuki Yamaguchi ◽  
Kotaro Kohno ◽  
Bunyo Hatsukade ◽  
Tao Wang ◽  
Yuki Yoshimura ◽  
...  

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 >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.


2019 ◽  
Vol 489 (1) ◽  
pp. 339-348 ◽  
Author(s):  
Ho Seong Hwang ◽  
Jihye Shin ◽  
Hyunmi Song

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.


2020 ◽  
Vol 492 (4) ◽  
pp. 5592-5606 ◽  
Author(s):  
A Katsianis ◽  
V Gonzalez ◽  
D Barrientos ◽  
X Yang ◽  
C D P Lagos ◽  
...  

ABSTRACT There is a severe tension between the observed star formation rate (SFR)–stellar mass (M⋆) relations reported by different authors at z = 1–4. In addition, the observations have not been successfully reproduced by state-of-the-art cosmological simulations that tend to predict a factor of 2–4 smaller SFRs at a fixed M⋆. We examine the evolution of the SFR–M⋆ relation of z = 1–4 galaxies using the skirt simulated spectral energy distributions of galaxies sampled from the Evolution and Assembly of GaLaxies and their Environments simulations. We derive SFRs and stellar masses by mimicking different observational techniques. We find that the tension between observed and simulated SFR–M⋆ relations is largely alleviated if similar methods are used to infer the galaxy properties. We find that relations relying on infrared wavelengths (e.g. 24 ${\rm \, \mu m}$, MIPS – 24, 70, and 160 ${\rm \, \mu m}$ or SPIRE – 250, 350, and 500 ${\rm \, \mu m}$) have SFRs that exceed the intrinsic relation by 0.5 dex. Relations that rely on the spectral energy distribution fitting technique underpredict the SFRs at a fixed stellar mass by −0.5 dex at z ∼ 4 but overpredict the measurements by 0.3 dex at z ∼ 1. Relations relying on dust-corrected rest-frame ultraviolet luminosities, are flatter since they overpredict/underpredict SFRs for low/high star-forming objects and yield deviations from the intrinsic relation from 0.10 to −0.13 dex at z ∼ 4. We suggest that the severe tension between different observational studies can be broadly explained by the fact that different groups employ different techniques to infer their SFRs.


2018 ◽  
Vol 609 ◽  
pp. A82 ◽  
Author(s):  
L. Bisigello ◽  
K. I. Caputi ◽  
N. Grogin ◽  
A. Koekemoer

The analysis of galaxies on the star formation rate-stellar mass (SFR–M∗) plane is a powerful diagnostic for galaxy evolution at different cosmic times. We consider a sample of 24 463 galaxies from the CANDELS/GOODS-S survey to conduct a detailed analysis of the SFR–M∗ relation at redshifts 0.5 ⩽ z<3 over more than three dex in stellar mass. To obtain SFR estimates, we utilise mid- and far-IR photometry when available, and rest-UV fluxes for all the other galaxies. We perform our analysis in different redshift bins, with two different methods: 1) a linear regression fitting of all star-forming galaxies, defined as those with specific SFRs log 10(sSFR/ yr-1) > −9.8, similarly to what is typically done in the literature; 2) a multi-Gaussian decomposition to identify the galaxy main sequence (MS), the starburst sequence and the quenched galaxy cloud. We find that the MS slope becomes flatter when higher stellar mass cuts are adopted, and that the apparent slope change observed at high masses depends on the SFR estimation method. In addition, the multi-Gaussian decomposition reveals the presence of a starburst population which increases towards low stellar masses and high redshifts. We find that starbursts make up ~ 5% of all galaxies at z = 0.5−1.0, while they account for ~ 16% of galaxies at 2 <z< 3 with log10(M∗/M0) = 8.25–11.25. We conclude that the dissection of the SFR–M∗ in multiple components over a wide range of stellar masses is necessary to understand the importance of the different modes of star formation through cosmic time.


Author(s):  
P Bonfini ◽  
A Zezas ◽  
M L N Ashby ◽  
S P Willner ◽  
A Maragkoudakis ◽  
...  

Abstract We constrain the mass distribution in nearby, star-forming galaxies with the Star Formation Reference Survey (SFRS), a galaxy sample constructed to be representative of all known combinations of star formation rate (SFR), dust temperature, and specific star formation rate (sSFR) that exist in the Local Universe. An innovative two-dimensional bulge/disk decomposition of the 2MASS/Ks-band images of the SFRS galaxies yields global luminosity and stellar mass functions, along with separate mass functions for their bulges and disks. These accurate mass functions cover the full range from dwarf galaxies to large spirals, and are representative of star-forming galaxies selected based on their infra-red luminosity, unbiased by AGN content and environment. We measure an integrated luminosity density j = 1.72 ± 0.93 × 109 L⊙  h−1 Mpc−3 and a total stellar mass density ρM = 4.61 ± 2.40 × 108 M⊙  h−1 Mpc−3. While the stellar mass of the average star-forming galaxy is equally distributed between its sub-components, disks globally dominate the mass density budget by a ratio 4:1 with respect to bulges. In particular, our functions suggest that recent star formation happened primarily in massive systems, where they have yielded a disk stellar mass density larger than that of bulges by more than 1 dex. Our results constitute a reference benchmark for models addressing the assembly of stellar mass on the bulges and disks of local (z = 0) star-forming galaxies.


2020 ◽  
Vol 493 (4) ◽  
pp. 5596-5605 ◽  
Author(s):  
Robin H W Cook ◽  
Luca Cortese ◽  
Barbara Catinella ◽  
Aaron Robotham

ABSTRACT We use our catalogue of structural decomposition measurements for the extended GALEX Arecibo SDSS Survey (xGASS) to study the role of bulges both along and across the galaxy star-forming main sequence (SFMS). We show that the slope in the sSFR–M⋆ relation flattens by ∼0.1 dex per decade in M⋆ when re-normalizing specifice star formation rate (sSFR) by disc stellar mass instead of total stellar mass. However, recasting the sSFR–M⋆ relation into the framework of only disc-specific quantities shows that a residual trend remains against disc stellar mass with equivalent slope and comparable scatter to that of the total galaxy relation. This suggests that the residual declining slope of the SFMS is intrinsic to the disc components of galaxies. We further investigate the distribution of bulge-to-total ratios (B/T) as a function of distance from the SFMS (ΔSFRMS). At all stellar masses, the average B/T of local galaxies decreases monotonically with increasing ΔSFRMS. Contrary to previous works, we find that the upper envelope of the SFMS is not dominated by objects with a significant bulge component. This rules out a scenario in which, in the local Universe, objects with increased star formation activity are simultaneously experiencing a significant bulge growth. We suggest that much of the discrepancies between different works studying the role of bulges originate from differences in the methodology of structurally decomposing galaxies.


Author(s):  
J K Barrera-Ballesteros ◽  
S F Sánchez ◽  
T Heckman ◽  
T Wong ◽  
A Bolatto ◽  
...  

Abstract The processes that regulate star formation are essential to understand how galaxies evolve. We present the relation between star formation rate density, ΣSFR , and hydrostatic midplane pressure, Ph , for 4260 star-forming regions of kpc size located in 96 galaxies included in the EDGE-CALIFA survey covering a wide range of stellar masses and morphologies. We find that these two parameters are tightly correlated, showing a smaller scatter in comparison to other star-forming relations. A power-law, with a slightly sub-linear index, is a good representation of this relation. Its residuals show a significant anti-correlation with both stellar age and metallicity whereas the total stellar mass may also play a secondary role in shaping the ΣSFR - Ph relation. For actively star-forming regions we find that the effective feedback momentum per unit stellar mass (p*/m*), measured from the Ph/ΣSFR ratio increases with Ph. The median value of this ratio for all the sampled regions is larger than the expected momentum just from supernovae explosions. Morphology of the galaxies, including bars, does not seem to have a significant impact in the ΣSFR - Ph relation. Our analysis indicates that local ΣSFR self-regulation comes mainly from momentum injection to the interstellar medium from supernovae explosions. However, other mechanisms in disk galaxies may also play a significant role in shaping the ΣSFR at kpc scales. Our results also suggest that Ph is the main parameter that modulates star formation at kpc scales, rather than individual components of the baryonic mass.


2018 ◽  
Vol 620 ◽  
pp. A113 ◽  
Author(s):  
M. Argudo-Fernández ◽  
I. Lacerna ◽  
S. Duarte Puertas

Context. Galaxy mass and environment play a major role in the evolution of galaxies. In the transition from star-forming to quenched galaxies, active galactic nuclei (AGNs) also have a principal action therein. However, the connections between these three actors are still uncertain. Aims. In this work we investigate the effects of stellar mass and the large-scale structure (LSS) environment on the fraction of optical nuclear activity in a population of isolated galaxies, where AGN would not be triggered by recent galaxy interactions or mergers. Methods. As a continuation of a previous work, we focus on isolated galaxies to study the effect of stellar mass and the LSS in terms of morphology (early- and late-type), colour (red and blue), and specific star-formation rate (quenched and star-forming). To explore where AGN activity is affected by the LSS, we separate galaxies into two groups, of low- and high mass, respectively, and use the tidal strength parameter to quantify the effects. Results. We found that AGN is strongly affected by stellar mass in “active” galaxies (namely late-type, blue, and star-forming), but that mass has no influence on “quiescent” galaxies (namely early-type, red, and quenched), at least for masses down to 1010 M⊙. In relation to the LSS, we found an increase in the fraction of star-forming nuclei galaxies with denser LSS in low-mass star-forming and red isolated galaxies. Regarding AGN, we find a clear increase in the fraction of AGNs with denser environment in quenched and red isolated galaxies, independently of the stellar mass. Conclusions. Active galactic nuclei activity appears to be “mass triggered” in active isolated galaxies. This means that AGN activity is independent of the intrinsic properties of the galaxies, but is dependent on their stellar mass. On the other hand, AGN activity appears to be “environment triggered” in quiescent isolated galaxies, where the fraction of AGNs as a function of specific star formation rate and colour increases from void regions to denser LSS, independently of stellar mass.


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