scholarly journals Galaxy pairs in the Sloan Digital Sky Survey – XIV. Galaxy mergers do not lie on the fundamental metallicity relation

2020 ◽  
Vol 494 (3) ◽  
pp. 3469-3480 ◽  
Author(s):  
Sebastián Bustamante ◽  
Sara L Ellison ◽  
David R Patton ◽  
Martin Sparre
Keyword(s):  
Star Formation ◽  
Gas Phase ◽  
Formation Rate ◽  
Local Environment ◽  
Stellar Mass ◽  
Sloan Digital Sky Survey ◽  
Galaxy Mergers ◽  
Star Forming ◽  
Sky Survey ◽  
Evolutionary Phase

ABSTRACT In recent observational studies, star-forming galaxies have been shown to follow a relation often dubbed the fundamental metallicity relation (FMR). This relation links the stellar mass of a galaxy with its star formation rate (SFR) and its gas-phase metallicity. Specifically, the FMR predicts that galaxies, at a given stellar mass, exhibit lower metallicities for higher SFRs. This trend is qualitatively consistent with observations of galaxy pairs, which have been robustly shown to experience increasing gas-phase metallicity dilution and enhanced star formation activity with decreasing projected separation. In this work, we show that, despite the qualitative consistency with FMR expectations, the observed O/H dilution in galaxy pairs of the Sloan Digital Sky Survey is stronger than what is predicted by the FMR. We conclude that the evolutionary phase of galaxies interacting with companions is not encoded in the FMR, and thus, mergers constitute a clearly defined population of outliers. We find that galaxies in pairs are consistent with the FMR only when their separation is larger than 110 kpc. Finally, we also quantify the local environment of the pairs using the number of galaxy neighbours within 2 Mpc, N2, and the projected separation to the second closest galaxy, r2. We find that pairs are more sensitive to a second companion than to the local galaxy density, displaying less elevated SFRs with smaller values of r2.

scholarly journals Redshift measurement through star formation

2019 ◽  
Vol 629 ◽  
pp. A7
Author(s):  
Mikkel O. Lindholmer ◽  
Kevin A. Pimbblet
Keyword(s):  
Star Formation ◽  
Galaxy Clusters ◽  
Main Sequence ◽  
Formation Rate ◽  
Sloan Digital Sky Survey ◽  
X Ray ◽  
Star Forming ◽  
Sky Survey ◽  
The Galaxy ◽  
Galaxy Population

In this work we use the property that, on average, star formation rate increases with redshift for objects with the same mass – the so called galaxy main sequence – to measure the redshift of galaxy clusters. We use the fact that the general galaxy population forms both a quenched and a star-forming sequence, and we locate these ridges in the SFR–M⋆ plane with galaxies taken from the Sloan Digital Sky Survey in discrete redshift bins. We fitted the evolution of the galaxy main sequence with redshift using a new method and then subsequently apply our method to a suite of X-ray selected galaxy clusters in an attempt to create a new distance measurement to clusters based on their galaxy main sequence. We demonstrate that although it is possible in several galaxy clusters to measure the main sequences, the derived distance and redshift from our galaxy main sequence fitting technique has an accuracy of σz = ±0.017 ⋅ (z + 1) and is only accurate up to z ≈ 0.2.

scholarly journals What is Important? Morphological Asymmetries are Useful Predictors of Star Formation Rates of Star-forming Galaxies in SDSS Stripe 82

2021 ◽  
Vol 923 (2) ◽  
pp. 205
Author(s):  
Hassen M. Yesuf ◽  
Luis C. Ho ◽  
S. M. Faber
Keyword(s):  
Star Formation ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Sloan Digital Sky Survey ◽  
Imaging Data ◽  
Galaxy Interactions ◽  
Star Forming ◽  
Sky Survey ◽  
Structural Variables ◽  
Central Concentration

Abstract The morphology and structure of galaxies reflect their star formation and assembly histories. We use the framework of mutual information (MI) to quantify the interdependence among several structural variables and to rank them according to their relevance for predicting the specific star formation rate (SSFR) by comparing the MI of the predictor variables with the SSFR and penalizing variables that are redundant. We apply this framework to study ∼3700 face-on star-forming galaxies (SFGs) with varying degrees of bulge dominance and central concentration and with stellar mass M ⋆ ≈ 109 M ⊙−5 × 1011 M ⊙ at redshift z = 0.02–0.12. We use the Sloan Digital Sky Survey (SDSS) Stripe 82 deep i-band imaging data, which improve measurements of asymmetry and bulge dominance indicators. We find that star-forming galaxies are a multiparameter family. In addition to M ⋆, asymmetry emerges as the most powerful predictor of SSFR residuals of SFGs, followed by bulge prominence/concentration. Star-forming galaxies with higher asymmetry and stronger bulges have higher SSFR at a given M ⋆. The asymmetry reflects both irregular spiral arms and lopsidedness in seemingly isolated SFGs and structural perturbations by galaxy interactions or mergers.

scholarly journals Comparison of Composite and Star-forming Early-type Galaxies

2021 ◽  
Vol 163 (1) ◽  
pp. 28
Author(s):  
Yu-Zhong Wu
Keyword(s):  
Star Formation ◽  
Stellar Mass ◽  
Sloan Digital Sky Survey ◽  
Early Type ◽  
Massive Galaxies ◽  
Star Forming ◽  
Sky Survey ◽  
Excitation Mechanisms ◽  
Stellar Masses ◽  
Evolution Scheme

Abstract I assemble 4684 star-forming early-type galaxies (ETGs) and 2011 composite ETGs (located in the composite region on the BPT diagram) from the catalog of the Sloan Digital Sky Survey Data Release 7 MPA-JHU emission-line measurements. I compare the properties of both ETG samples and investigate their compositions, stellar masses, specific star formation rates (sSFRs), and excitation mechanisms. Compared with star-forming ETGs, composite ETGs have higher stellar mass and lower sSFR. In the stellar mass and u − r color diagram, more than 60% of star-forming ETGs and composite ETGs are located in the green valley, showing that the two ETG samples may have experienced star formation and that ∼17% of star-forming ETGs lie in the blue cloud, while ∼30% of composite ETGs lie in the red sequence. In the [N II]/Hα versus EWHα (the Hα equivalent width) diagram, all star-forming ETGs and most of the composite ETGs are located in the star-forming galaxy region, and composite ETGs have lower EWHα than their counterparts. We show the relations between 12+log(O/H) and log(N/O) for both ETG samples, and suggest that nitrogen production of some star-forming ETGs can be explained by the evolution scheme of Coziol et al., while the prodution of composite ETGs may be a consequence of the inflowing of metal-poor gas and these more evolved massive galaxies.

scholarly journals The Evolution of Gas-Phase Metallicity and Resolved Abundances in Star-forming Galaxies at z ≈ 0.6 – 1.8

2020 ◽  
Author(s):  
S Gillman ◽  
A L Tiley ◽  
A M Swinbank ◽  
U Dudzevičiūtė ◽  
R M Sharples ◽  
...  
Keyword(s):  
Star Formation ◽  
Gas Phase ◽  
Galaxy Evolution ◽  
Star Formation Rate ◽  
Numerical Models ◽  
Formation Rate ◽  
Stellar Mass ◽  
Radial Dependence ◽  
Chemical Abundance ◽  
Star Forming

Abstract We present an analysis of the chemical abundance properties of ≈650 star-forming galaxies at z ≈ 0.6 – 1.8. Using integral-field observations from the K - band Multi-Object Spectrograph (KMOS), we quantify the [N ii]/Hα emission-line ratio, a proxy for the gas-phase Oxygen abundance within the interstellar medium. We define the stellar mass – metallicity relation at z ≈ 0.6 – 1.0 and z ≈ 1.2 – 1.8 and analyse the correlation between the scatter in the relation and fundamental galaxy properties (e.g. Hα star-formation rate, Hα specific star-formation rate, rotation dominance, stellar continuum half-light radius and Hubble-type morphology). We find that for a given stellar mass, more highly star-forming, larger and irregular galaxies have lower gas-phase metallicities, which may be attributable to their lower surface mass densities and the higher gas fractions of irregular systems. We measure the radial dependence of gas-phase metallicity in the galaxies, establishing a median, beam smearing-corrected, metallicity gradient of ΔZ/ΔR= 0.002 ± 0.004 dex kpc−1, indicating on average there is no significant dependence on radius. The metallicity gradient of a galaxy is independent of its rest-frame optical morphology, whilst correlating with its stellar mass and specific star-formation rate, in agreement with an inside-out model of galaxy evolution, as well as its rotation dominance. We quantify the evolution of metallicity gradients, comparing the distribution of ΔZ/ΔR in our sample with numerical simulations and observations at z ≈ 0 – 3. Galaxies in our sample exhibit flatter metallicity gradients than local star-forming galaxies, in agreement with numerical models in which stellar feedback plays a crucial role redistributing metals.

scholarly journals Interacting galaxies in the IllustrisTNG simulations - I: Triggered star formation in a cosmological context

2020 ◽  
Vol 494 (4) ◽  
pp. 4969-4985 ◽  
Author(s):  
David R Patton ◽  
Kieran D Wilson ◽  
Colin J Metrow ◽  
Sara L Ellison ◽  
Paul Torrey ◽  
...  
Keyword(s):  
Star Formation ◽  
Local Density ◽  
Stellar Mass ◽  
Sloan Digital Sky Survey ◽  
Massive Galaxies ◽  
Star Forming ◽  
Cosmological Context ◽  
Sky Survey ◽  
The Mean ◽  
Hydrodynamical Simulations

ABSTRACT We use the IllustrisTNG cosmological hydrodynamical simulations to investigate how the specific star formation rates (sSFRs) of massive galaxies (M* > 1010 M⊙) depend on the distance to their closest companions. We estimate sSFR enhancements by comparing with control samples that are matched in redshift, stellar mass, local density, and isolation, and we restrict our analysis to pairs with stellar mass ratios of 0.1 to 10. At small separations (∼15 kpc), the mean sSFR is enhanced by a factor of 2.0 ± 0.1 in the flagship (110.7 Mpc)3 simulation (TNG100-1). Statistically significant enhancements extend out to 3D separations of 280 kpc in the (302.6 Mpc)3 simulation (TNG300-1). We find similar trends in the EAGLE and Illustris simulations, although their sSFR enhancements are lower than those in TNG100-1 by about a factor of two. Enhancements in IllustrisTNG galaxies are seen throughout the redshift range explored (0 ≤ $z$ < 1), with the strength of the enhancements decreasing with increasing redshift for galaxies with close companions. In order to more closely compare with observational results, we separately consider 2D projected distances between galaxies in IllustrisTNG. We detect significant sSFR enhancements out to projected separations of 260 kpc in TNG300-1, with projection effects diluting the size of the enhancements by about 20 per cent below 50 kpc. We find similar sSFR enhancements in TNG100-1 and Sloan Digital Sky Survey galaxies, with enhancements extending out to projected separations of about 150 kpc for star-forming galaxies at $z$ < 0.2. Finally, by summing over all separations, we estimate that the presence of closest companions boosts the average sSFR of massive galaxies in TNG100-1 by 14.5 per cent.

scholarly journals Star-forming Dwarf Galaxies in Filamentary Structures around the Virgo Cluster: Probing Chemical Pre-processing in Filament Environments

2021 ◽  
Vol 923 (2) ◽  
pp. 235
Author(s):  
Jiwon Chung ◽  
Suk Kim ◽  
Soo-Chang Rey ◽  
Youngdae Lee
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Dwarf Galaxies ◽  
Formation Rate ◽  
Chemical Properties ◽  
Local Environment ◽  
Stellar Mass ◽  
Virgo Cluster ◽  
Star Forming ◽  
The Galaxy

Abstract It has been proposed that the filament environment is closely connected to the pre-processing of galaxies, where their properties may have been changed by environmental effects in the filament before they fell into the galaxy cluster. We present the chemical properties of star-forming dwarf galaxies (SFDGs) in five filamentary structures (Virgo III, Leo Minor, Leo II A, Leo II B, and Canes Venatici) around the Virgo cluster using the Sloan Digital Sky Survey optical spectroscopic data and Galaxy Evolution Explorer ultraviolet photometric data. We investigate the relationship between stellar mass, gas-phase metallicity, and specific star formation rate (sSFR) of the SFDGs in the Virgo filaments in comparison to those in the Virgo cluster and field. We find that, at a given stellar mass, SFDGs in the Virgo filaments show lower metallicity and higher sSFR than those in the Virgo cluster on average. We observe that SFDGs in the Virgo III filament show enhanced metallicities and suppressed star formation activities comparable to those in the Virgo cluster, whereas SFDGs in the other four filaments exhibit similar properties to the field counterparts. Moreover, about half of the galaxies in the Virgo III filament are found to be morphologically transitional dwarf galaxies that are supposed to be on the way to transforming into quiescent dwarf early-type galaxies. Based on the analysis of the galaxy perturbation parameter, we propose that the local environment represented by the galaxy interactions might be responsible for the contrasting features in chemical pre-processing found in the Virgo filaments.

scholarly journals Gas accretion as fuel for residual star formation in Galaxy Zoo elliptical galaxies

2019 ◽  
Vol 489 (1) ◽  
pp. L108-L113 ◽  
Author(s):  
Timothy A Davis ◽  
Lisa M Young
Keyword(s):  
Star Formation ◽  
Gas Phase ◽  
External Source ◽  
Elliptical Galaxies ◽  
Sloan Digital Sky Survey ◽  
Star Forming ◽  
Sky Survey ◽  
Low Metallicity ◽  
Minor Mergers ◽  
Gas Accretion

ABSTRACT In this letter we construct a large sample of early-type galaxies (ETGs) with measured gas-phase metallicities from the Sloan Digital Sky Survey and Galaxy Zoo in order to investigate the origin of the gas that fuels their residual star formation. We use this sample to show that star-forming elliptical galaxies have a substantially different gas-phase metallicity distribution from spiral galaxies, with ≈7.4 per cent having a very low gas-phase metallicity for their mass. These systems typically have fewer metals in the gas phase than they do in their stellar photospheres, which strongly suggests that the material fuelling their recent star formation was accreted from an external source. We use a chemical evolution model to show that the enrichment time-scale for low-metallicity gas is very short, and thus that cosmological accretion and minor mergers are likely to supply the gas in ≳ 37 per cent of star-forming ETGs, in good agreement with estimates derived from other independent techniques.

scholarly journals The specific star formation rate function at different mass scales and quenching: a comparison between cosmological models and SDSS

2020 ◽  
Vol 500 (2) ◽  
pp. 2036-2048
Author(s):  
Antonios Katsianis ◽  
Haojie Xu ◽  
Xiaohu Yang ◽  
Yu Luo ◽  
Weiguang Cui ◽  
...  
Keyword(s):  
Star Formation ◽  
Star Formation Rate ◽  
State Of The Art ◽  
Formation Rate ◽  
Rate Function ◽  
Stellar Mass ◽  
Cosmological Models ◽  
Sloan Digital Sky Survey ◽  
Star Forming ◽  
Low Mass

ABSTRACT We present the eddington bias corrected specific star formation rate function (sSFRF) at different stellar mass scales from a sub-sample of the Sloan Digital Sky Survey Data Release DR7 (SDSS), which is considered complete both in terms of stellar mass (M⋆) and star formation rate (SFR). The above enable us to study qualitatively and quantitatively quenching, the distribution of passive/star-forming galaxies and perform comparisons with the predictions from state-of-the-art cosmological models, within the same M⋆ and SFR limits. We find that at the low-mass end (${M_{\star }} = 10^{9.5}\!-\!10^{10} \, {\rm M_{\odot }}$) the sSFRF is mostly dominated by star-forming objects. However, moving to the two more massive bins (${M_{\star }} = 10^{10}\!-\!10^{10.5} \, {\rm M_{\odot }}$ and ${M_{\star }} = 10^{10.5}\!-\!10^{11} \, {\rm M_{\odot }}$) a bi-modality with two peaks emerges. One peak represents the star-forming population, while the other describes a rising passive population. The bi-modal form of the sSFRFs is not reproduced by a range of cosmological simulations (e.g. Illustris, EAGLE, Mufasa, and IllustrisTNG) which instead generate mostly the star-forming population, while a bi-modality emerges in others (e.g. L-Galaxies, Shark, and Simba). Our findings reflect the need for the employed quenching schemes in state-of-the-art models to be reconsidered, involving prescriptions that allow ‘quenched galaxies’ to retain a small level of SF activity (sSFR = ${\rm 10^{-11} \, }$–${\rm 10^{-12} \, {\rm yr^{-1}}}$) and generate an adequate passive population/bi-modality even at intermediate masses (${M_{\star }} = 10^{10}\!-\!10^{10.5} \, {\rm M_{\odot }}$).

scholarly journals Correlations between mass, stellar kinematics, and gas metallicity in eagle galaxies

2020 ◽  
Vol 496 (1) ◽  
pp. L33-L37
Author(s):  
L J Zenocratti ◽  
M E De Rossi ◽  
M A Lara-López ◽  
T Theuns
Keyword(s):  
Star Formation ◽  
Dominant Role ◽  
Formation Rate ◽  
Galactic Nuclei ◽  
Stellar Mass ◽  
Galaxy Mergers ◽  
Stellar Kinematics ◽  
Star Forming ◽  
Stellar Feedback ◽  
Star Formation Histories

ABSTRACT The metallicity of star-forming gas in galaxies from the eagle (Evolution and Assembly of GaLaxies and their Environments) simulations increases with stellar mass. Here, we investigate whether the scatter around this relation correlates with morphology and/or stellar kinematics. At redshift z = 0, galaxies with more rotational support have lower metallicities on average when the stellar mass is below M⋆ ≈ 1010 M⊙. This trend inverts at higher values of M⋆, when prolate galaxies show typically lower metallicity. At increasing redshifts, the trend between rotational support and metallicity becomes weaker at low stellar mass but more pronounced at high stellar mass. We argue that the secondary dependence of metallicity on stellar kinematics is another manifestation of the observed anticorrelation between metallicity and star formation rate at a given stellar mass. At low masses, such trends seem to be driven by the different star formation histories of galaxies and stellar feedback. At high masses, feedback from active galactic nuclei and galaxy mergers plays a dominant role.

scholarly journals Characterizing the abundance, properties, and kinematics of the cool circumgalactic medium of galaxies in absorption with SDSS DR16

2021 ◽  
Vol 504 (1) ◽  
pp. 65-88
Author(s):  
Abhijeet Anand ◽  
Dylan Nelson ◽  
Guinevere Kauffmann
Keyword(s):  
Formation Rate ◽  
Sloan Digital Sky Survey ◽  
Gas Absorption ◽  
Dark Matter Halo ◽  
Star Forming ◽  
Sky Survey ◽  
Optical Continuum ◽  
Circumgalactic Medium ◽  
Emission Line Galaxies ◽  
Red Galaxies

ABSTRACT In order to study the circumgalactic medium (CGM) of galaxies we develop an automated pipeline to estimate the optical continuum of quasars and detect intervening metal absorption line systems with a matched kernel convolution technique and adaptive S/N criteria. We process ∼ one million quasars in the latest Data Release 16 (DR16) of the Sloan Digital Sky Survey (SDSS) and compile a large sample of ∼ 160 000 Mg ii absorbers, together with ∼ 70 000 Fe ii systems, in the redshift range 0.35 < zabs < 2.3. Combining these with the SDSS DR16 spectroscopy of ∼1.1 million luminous red galaxies (LRGs) and ∼200 000 emission line galaxies (ELGs), we investigate the nature of cold gas absorption at 0.5 < z < 1. These large samples allow us to characterize the scale dependence of Mg ii with greater accuracy than in previous work. We find that there is a strong enhancement of Mg ii absorption within ∼50 kpc of ELGs, and the covering fraction within 0.5rvir of ELGs is 2–5 times higher than for LRGs. Beyond 50 kpc, there is a sharp decline in Mg ii for both kinds of galaxies, indicating a transition to the regime where the CGM is tightly linked with the dark matter halo. The Mg ii-covering fraction correlates strongly with stellar mass for LRGs, but weakly for ELGs, where covering fractions increase with star formation rate. Our analysis implies that cool circumgalactic gas has a different physical origin for star-forming versus quiescent galaxies.

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