scholarly journals l-galaxies 2020: The evolution of radial metallicity profiles and global metallicities in disc galaxies

2021 ◽  
Author(s):  
Robert M Yates ◽  
Bruno M B Henriques ◽  
Jian Fu ◽  
Guinevere Kauffmann ◽  
Peter A Thomas ◽  
...  
Keyword(s):  
Gas Phase ◽  
Galaxy Evolution ◽  
Cosmic Time ◽  
Observational Result ◽  
Metal Enrichment ◽  
Lower Mass ◽  
Star Forming ◽  
Radial Profiles ◽  
Inside Out ◽  
Disc Galaxies

Abstract We present a modified version of the L-Galaxies 2020 semi-analytic model of galaxy evolution, which includes significantly increased direct metal enrichment of the circumgalactic medium (CGM) by supernovae (SNe). These more metal-rich outflows do not require increased mass-loading factors, in contrast to some other galaxy evolution models. This modified L-Galaxies 2020 model is able to simultaneously reproduce the gas-phase metallicity (Zg) and stellar metallicity (Z*) radial profiles observed in nearby disc galaxies by MaNGA and MUSE, as well as the observed mass – metallicity relations for gas and stars at z = 0 and their evolution back to z ∼ 2 − 3. A direct CGM enrichment fraction of ∼90 per cent for SNe-II is preferred. We find that massive disc galaxies have slightly flatter Zg profiles than their lower-mass counterparts in L-Galaxies 2020, due to more efficient enrichment of their outskirts via inside-out growth and metal-rich accretion. Such a weak, positive correlation between stellar mass and Zg profile slope is also seen in our MaNGA-DR15 sample of 571 star-forming disc galaxies, although below ${\rm log}_{10}{(M_{*}/{\rm M_\odot} )}{}\sim {}10.0$ this observational result is strongly dependent on the metallicity diagnostic and morphological selection chosen. In addition, a lowered maximum SN-II progenitor mass of 25 M⊙, reflecting recent theoretical and observational estimates, can also provide a good match to observed Zg and Z* profiles at z = 0 in L-Galaxies 2020. However, this model version fails to reproduce an evolution in Zg at fixed mass over cosmic time, or the magnesium abundances observed in the intracluster medium (ICM).

scholarly journals Spatially resolved signature of quenching in star-forming galaxies

2019 ◽  
Vol 490 (2) ◽  
pp. 2347-2366 ◽  
Author(s):  
Salvatore Quai ◽  
Lucia Pozzetti ◽  
Michele Moresco ◽  
Annalisa Citro ◽  
Andrea Cimatti ◽  
...  
Keyword(s):  
Star Formation ◽  
Gas Phase ◽  
Galaxy Evolution ◽  
Spatial Information ◽  
Formation Rate ◽  
Radial Profile ◽  
Control Sample ◽  
Star Forming ◽  
Radial Profiles ◽  
Two Samples

ABSTRACT Understanding when, how, and where star formation ceased (quenching) within galaxies is still a critical subject in galaxy evolution studies. Taking advantage of the new methodology developed by Quai et al. to select recently quenched galaxies, we explored the spatial information provided by the IFU data to get critical insights on this process. In particular, we analyse 10 SDSS-IV MaNGA galaxies that show regions with low [O iii]/H α compatible with a recent quenching of the star formation. We compare the properties of these 10 galaxies with those of a control sample of 8 MaNGA galaxies with ongoing star formation in the same stellar mass, redshift, and gas-phase metallicity range. The quenching regions found are located between 0.5 and 1.1 effective radii from the centre. This result is supported by the analysis of the average radial profile of the ionization parameter, which reaches a minimum at the same radii, while the one of the star-forming sample shows an almost flat trend. These quenching regions occupy a total area between ∼ 15 and 45 per cent of our galaxies. Moreover, the average radial profile of the star formation rate surface density of our sample is lower and flatter than that of the control sample, at any radii, suggesting a systematic suppression of the star formation in the inner part of our galaxies. Finally, the radial profiles of gas-phase metallicity of the two samples have a similar slope and normalization. Our results cannot be ascribed to a difference in the intrinsic properties of the analysed galaxies, suggesting a quenching scenario more complicated than a simple inside-out quenching.

scholarly journals Most of the cool CGM of star-forming galaxies is not produced by supernova feedback

2020 ◽  
Author(s):  
Andrea Afruni ◽  
Filippo Fraternali ◽  
Gabriele Pezzulli
Keyword(s):  
Galaxy Evolution ◽  
Cosmic Time ◽  
Energy Coupling ◽  
High Energy ◽  
Parametric Models ◽  
Star Forming ◽  
Galaxy Halos ◽  
The Galaxy ◽  
Supernova Explosions ◽  
Cool Gas

Abstract The characterization of the large amount of gas residing in the galaxy halos, the so called circumgalactic medium (CGM), is crucial to understand galaxy evolution across cosmic time. We focus here on the the cool (T ∼ 104 K) phase of this medium around star-forming galaxies in the local universe, whose properties and dynamics are poorly understood. We developed semi-analytical parametric models to describe the cool CGM as an outflow of gas clouds from the central galaxy, as a result of supernova explosions in the disc (galactic wind). The cloud motion is driven by the galaxy gravitational pull and by the interactions with the hot (T ∼ 106 K) coronal gas. Through a bayesian analysis, we compare the predictions of our models with the data of the COS-Halos and COS-GASS surveys, which provide accurate kinematic information of the cool CGM around more than 40 low-redshift star-forming galaxies, probing distances up to the galaxy virial radii. Our findings clearly show that a supernova-driven outflow model is not suitable to describe the dynamics of the cool circumgalactic gas. Indeed, to reproduce the data, we need extreme scenarios, with initial outflow velocities and mass loading factors that would lead to unphysically high energy coupling from the supernovae to the gas and with supernova efficiencies largely exceeding unity. This strongly suggests that, since the outflows cannot reproduce most of the cool gas absorbers, the latter are likely the result of cosmological inflow in the outer galaxy halos, in analogy to what we have previously found for early-type galaxies.

scholarly journals Measuring the H i Content of Individual Galaxies Out to the Epoch of Reionization with [C ii]

2021 ◽  
Vol 922 (2) ◽  
pp. 147
Author(s):  
Kasper E. Heintz ◽  
Darach Watson ◽  
Pascal A. Oesch ◽  
Desika Narayanan ◽  
Suzanne C. Madden
Keyword(s):  
Galaxy Evolution ◽  
Conversion Factor ◽  
Mass Density ◽  
Cosmic Time ◽  
Gas Content ◽  
Universal Relation ◽  
New Approach ◽  
Star Forming ◽  
Baryonic Mass ◽  
Individual Galaxies

Abstract The H i gas content is a key ingredient in galaxy evolution, the study of which has been limited to moderate cosmological distances for individual galaxies due to the weakness of the hyperfine H i 21 cm transition. Here we present a new approach that allows us to infer the H i gas mass M HI of individual galaxies up to z ≈ 6, based on a direct measurement of the [C ii]-to-H i conversion factor in star-forming galaxies at z ≳ 2 using γ-ray burst afterglows. By compiling recent [C ii]-158 μm emission line measurements we quantify the evolution of the H i content in galaxies through cosmic time. We find that M HI starts to exceed the stellar mass M ⋆ at z ≳ 1, and increases as a function of redshift. The H i fraction of the total baryonic mass increases from around 20% at z = 0 to about 60% at z ∼ 6. We further uncover a universal relation between the H i gas fraction M HI/M ⋆ and the gas-phase metallicity, which seems to hold from z ≈ 6 to z = 0. The majority of galaxies at z > 2 are observed to have H i depletion times, t dep,HI = M HI/SFR, less than ≈2 Gyr, substantially shorter than for z ∼ 0 galaxies. Finally, we use the [C ii]-to-H i conversion factor to determine the cosmic mass density of H i in galaxies, ρ HI, at three distinct epochs: z ≈ 0, z ≈ 2, and z ∼ 4–6. These measurements are consistent with previous estimates based on 21 cm H i observations in the local universe and with damped Lyα absorbers (DLAs) at z ≳ 2, suggesting an overall decrease by a factor of ≈5 in ρ HI(z) from the end of the reionization epoch to the present.

scholarly journals Angular Momentum Accretion onto Disc Galaxies

2018 ◽  
Vol 14 (A30) ◽  
pp. 228-232
Author(s):  
Filippo Fraternali ◽  
Gabriele Pezzulli
Keyword(s):  
Angular Momentum ◽  
Star Formation ◽  
Momentum Distribution ◽  
Intergalactic Medium ◽  
Star Forming ◽  
Gas Accretion ◽  
Hot Corona ◽  
Inside Out ◽  
Disc Galaxies ◽  
Hubble Time

AbstractThroughout the Hubble time, gas makes its way from the intergalactic medium into galaxies fuelling their star formation and promoting their growth. One of the key properties of the accreting gas is its angular momentum, which has profound implications for the evolution of, in particular, disc galaxies. Here, we discuss how to infer the angular momentum of the accreting gas using observations of present-day galaxy discs. We first summarize evidence for ongoing inside-out growth of star forming discs. We then focus on the chemistry of the discs and show how the observed metallicity gradients can be explained if gas accretes onto a disc rotating with a velocity 20 – 30% lower than the local circular speed. We also show that these gradients are incompatible with accretion occurring at the edge of the discs and flowing radially inward. Finally, we investigate gas accretion from a hot corona with a cosmological angular momentum distribution and describe how simple models of rotating coronae guarantee the inside-out growth of disc galaxies.

scholarly journals Observational Searches for Star-Forming Galaxies at z > 6

2016 ◽  
Vol 33 ◽  
Author(s):  
Steven L. Finkelstein
Keyword(s):  
Galaxy Evolution ◽  
Galaxy Formation ◽  
Cosmic Time ◽  
Mass Function ◽  
Star Forming ◽  
Chemical Enrichment ◽  
Large Samples ◽  
Galaxy Formation And Evolution ◽  
Observational Techniques ◽  
The Universe

AbstractAlthough the universe at redshifts greater than six represents only the first one billion years (< 10%) of cosmic time, the dense nature of the early universe led to vigorous galaxy formation and evolution activity which we are only now starting to piece together. Technological improvements have, over only the past decade, allowed large samples of galaxies at such high redshifts to be collected, providing a glimpse into the epoch of formation of the first stars and galaxies. A wide variety of observational techniques have led to the discovery of thousands of galaxy candidates at z > 6, with spectroscopically confirmed galaxies out to nearly z = 9. Using these large samples, we have begun to gain a physical insight into the processes inherent in galaxy evolution at early times. In this review, I will discuss (i) the selection techniques for finding distant galaxies, including a summary of previous and ongoing ground and space-based searches, and spectroscopic follow-up efforts, (ii) insights into galaxy evolution gleaned from measures such as the rest-frame ultraviolet luminosity function, the stellar mass function, and galaxy star-formation rates, and (iii) the effect of galaxies on their surrounding environment, including the chemical enrichment of the universe, and the reionisation of the intergalactic medium. Finally, I conclude with prospects for future observational study of the distant universe, using a bevy of new state-of-the-art facilities coming online over the next decade and beyond.

scholarly journals Galaxies in most dense environments at z ~ 1.4

2012 ◽  
Vol 10 (H16) ◽  
pp. 377-377
Author(s):  
V. Strazzullo
Keyword(s):  
Galaxy Evolution ◽  
High Redshift ◽  
Cosmic Time ◽  
Cluster Center ◽  
Final Conclusion ◽  
Early Type ◽  
Massive Galaxies ◽  
Star Forming ◽  
Cluster Cores ◽  
Red Sequence

AbstractThe X-ray luminous system XMMU J2235-2557 at z~1.4 is among the most massive of the very distant galaxy clusters, and remains a unique laboratory to observe environment-biased galaxy evolution already 9 Gyr ago (Lidman et al.2008, Rosati et al.2009, Strazzullo et al.2010). At a cosmic time when cluster cores start showing evidence of a still active galaxy population, star-forming (M>1010M⊙) galaxies in XMMU J2235-2557 are typically located beyond ~250kpc from the cluster center, with the cluster core already effectively quenched and dominated by massive galaxies on a tight red sequence, showing early-type spectral features and bulge-dominated morphologies. While masses and stellar populations of these red-sequence galaxies suggest that they have largely completed their formation, their size is found to be typically smaller that similarly massive early-type galaxies in the local Universe, in agreement with many high-redshift studies. This would leave room for later evolution, likely through non-secular processes, changing their structure to match their local counterparts. On the other hand, uncertainties and biases in the determination of masses and sizes, as well as in the local mass-size relation, and the possible effect of progenitor bias, still hamper a final conclusion on the actual relevance of size evolution for early-type galaxies in this dense high-redshift environment.

scholarly journals Simulating MOS science on the ELT: Lyα forest tomography

2019 ◽  
Vol 632 ◽  
pp. A94 ◽  
Author(s):  
J. Japelj ◽  
C. Laigle ◽  
M. Puech ◽  
C. Pichon ◽  
H. Rahmani ◽  
...  
Keyword(s):  
Galaxy Evolution ◽  
Large Scale ◽  
Formation Rate ◽  
Cosmic Time ◽  
Observation Time ◽  
Star Forming ◽  
Hydrodynamical Simulation ◽  
Resolution Element ◽  
Scientific Potential

Mapping the large-scale structure through cosmic time has numerous applications in studies of cosmology and galaxy evolution. At z ≳ 2, the structure can be traced by the neutral intergalactic medium (IGM) by way of observing the Lyα forest towards densely sampled lines of sight of bright background sources, such as quasars and star-forming galaxies. We investigate the scientific potential of MOSAIC, a planned multi-object spectrograph on the European Extremely Large Telescope (ELT), for the 3D mapping of the IGM at z ≳ 3. We simulated a survey of 3 ≲ z ≲ 4 galaxies down to a limiting magnitude of mr ∼ 25.5 mag in an area of 1 degree2 in the sky. Galaxies and their spectra (including the line-of-sight Lyα absorption) were taken from the lightcone extracted from the Horizon-AGN cosmological hydrodynamical simulation. The quality of the reconstruction of the original density field was studied for different spectral resolutions (R = 1000 and R = 2000, corresponding to the transverse typical scales of 2.5 and 4 Mpc) and signal-to-noise ratios (S/N) of the spectra. We demonstrate that the minimum S/N (per resolution element) of the faintest galaxies that a survey like this has to reach is S/N = 4. We show that a survey with this sensitivity enables a robust extraction of cosmic filaments and the detection of the theoretically predicted galaxy stellar mass and star-formation rate gradients towards filaments. By simulating the realistic performance of MOSAIC, we obtain S/N(Tobs, R, mr) scaling relations. We estimate that ≲35 (65) nights of observation time are required to carry out the survey with the instrument’s high multiplex mode and with a spectral resolution of R = 1000 (2000). A survey with a MOSAIC-concept instrument on the ELT is found to enable the mapping of the IGM at z >  3 on Mpc scales, and as such will be complementary to and competitive with other planned IGM tomography surveys.

scholarly journals J-PLUS: Impact of bars on quenching timescales in nearby green valley disc galaxies

2019 ◽  
Vol 630 ◽  
pp. A88
Author(s):  
J. P. Nogueira-Cavalcante ◽  
R. Dupke ◽  
P. Coelho ◽  
M. L. L. Dantas ◽  
T. S. Gonçalves ◽  
...  
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Clear Correlation ◽  
Spectral Indices ◽  
Local Universe ◽  
Star Forming ◽  
Magnitude Diagram ◽  
Star Formation Histories ◽  
The Impact ◽  
Disc Galaxies

Context. Between the blue cloud and the red sequence peaks on the galaxy colour–magnitude diagram there is a region sparsely populated by galaxies called the green valley. In a framework where galaxies mostly migrate on the colour–magnitude diagram from star forming to quiescent, the green valley is considered a transitional galaxy stage. The details of the processes that drive galaxies from star-forming to passive systems still remain unknown. Aims. We aim to measure the transitional timescales of nearby galaxies across the green valley, through the analysis of Galaxy Evolution Explorer and Javalambre Photometric of Local Universe Survey photometric data. Specifically, we seek to study the impact of bars on the quenching timescales. Methods. We developed a method that estimates empirically the star formation quenching timescales of green valley galaxies, assuming an exponential decay model of the star formation histories and through a combination of narrow and broad bands from the Javalambre Photometric of Local Universe Survey and Galaxy Evolution Explorer. We correlated these quenching timescales with the presence of bars. Results. We find that the Javalambre Photometric of Local Universe Survey colours F0395 −g and F0410 −g are sensitive to different star formation histories, showing, consequently, a clear correlation with the Dn(4000) and Hδ, A spectral indices. We measured quenching timescales based on these colours and we find that quenching timescales obtained with our new approach are in agreement with those determined using spectral indices. We also compared the quenching timescales of green valley disc galaxies as a function of the probability of hosting a bar. We find that galaxies with high bar probability tend to quench their star formation slowly. Conclusions. We conclude that: (1) Javalambre Photometric of Local Universe Survey filters can be used to measure quenching timescales in nearby green valley galaxies; and (2) the resulting star formation quenching timescales are longer for barred green valley galaxies. Considering that the presence of a bar indicates that more violent processes (e.g. major mergers) are absent in host galaxies, we conclude that the presence of a bar can be used as a morphological signature for slow star formation quenching.

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 Sub-galactic views of cold gas and dust in distant star-forming galaxies: Pushing the ∼ 100 pc frontier at z ∼ 3

2019 ◽  
Vol 15 (S352) ◽  
pp. 266-266
Author(s):  
Wiphu Rujopakarn
Keyword(s):  
Black Holes ◽  
Galaxy Evolution ◽  
Angular Resolution ◽  
Cosmic Time ◽  
First Year ◽  
Star Forming ◽  
Spatially Resolved ◽  
Resolution Capability ◽  
Synergistic Approach ◽  
Cold Gas

AbstractWhile the evolution of spatially-integrated properties of galaxies are relatively well constrained across cosmic time, many of the most fundamental processes are not well understood, especially down to the sub-galactic scales, where frontier questions in galaxy evolution lie: How did galactic spheroids form? How did galaxies and their supermassive black holes co-evolve? With the angular resolution capability of ∼tens of milliarcseconds, ALMA has conferred extinction- independent views of cold gas and dust distributions within individual z ∼ 1 – 4 galaxies at resolutions approaching ∼ 100 pc, thereby opening new avenues to study sub-galactic properties of galaxies at the peak of their assembly. In this talk, I will review recent findings and ongoing challenges enabled by ALMA's extinction-independent, spatially-resolved views of star forming galaxies, particularly the galactic substructures, e.g., clumps (or the lack thereof) from both field and gravitationally-lensed galaxies, and their implications on the bulge assembly scenario. I will also discuss a new synergistic approach between radio and millimeter observations (using, e.g., VLA and ALMA) to independently pinpoint the locations of star-forming region and AGN down to < 100 pc at z ∼ 3. Lastly, I will discuss the planned surveys with JWST in the first year of operation, and ways that the first datasets can be combined with ALMA to provide new breakthroughs and plan future observations to utilize Webb to the fullest.

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