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 Spatially resolved dynamics of high-z star forming galaxies

2008 ◽  
Vol 4 (S254) ◽  
pp. 33-34
Author(s):  
Reinhard Genzel
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Adaptive Optics ◽  
Disk Galaxies ◽  
Massive Galaxies ◽  
Star Forming ◽  
Secular Evolution ◽  
Spatially Resolved ◽  
The Impact ◽  
Integral Field

AbstractI report on two major programs to study the kinematic properties of galaxies at z ~ 1.5 − 3 with spatially resolved spectroscopy for the first time. Using the adaptive optics assisted, integral field spectrometer SINFONI on the ESO VLT, we have observed more than 70 galaxies and find compelling evidence for large, geometrically thick (turbulent), rotating disk galaxies in a majority of the objects that we can spatially resolve. It appears that these star forming disks are driven by continuous, rapid accretion of gas from their dark matter halos, and that their evolution is strongly influenced by internal, secular evolution. In contrast to the 20 submillimeter galaxies that we have investigated with the IRAM Plateau de Bure millimetre interferometer we find strong evidence for compact, major mergers. I discuss the impact of these new observations on our understanding of galaxy evolution in the early Universe.For the SINS survey we have carried out Hα integral field spectroscopy of well-resolved, UV/optically selected star-forming galaxies at z ~ 2 with SINFONI on the ESO VLT. The SINS sample is representative of the majority of massive (M* > a few 1010M⊙) star-forming galaxies at that redshift. Our data obtained with laser guide star assisted adaptive optics in good seeing show the presence of turbulent, rotating star-forming rings/disks in at least a third of the sample, plus central bulge/inner disk components in some of the best cases, whose mass fractions relative to total dynamical mass appears to scale with [NII]/Hα flux ratio and ‘star formation’ age. Another third of the SINS galaxies show clear signs of kinematic perturbations by a merger, while the last third appear to be compact, ‘dispersion’ limited systems.Our interpretation of these data is that the buildup of the central disks and bulges of massive galaxies at z ~ 2 can be driven by the early secular evolution of gas-rich ‘proto’-disks. High-redshift disks exhibit large random motions. This turbulence may in part be stirred up by the release of gravitational energy in the rapid ‘cold’ accretion flows along the filaments of the cosmic web. As a result, dynamical friction and viscous processes proceed on a time scale of < 1 Gyr, at least an order of magnitude faster than in disk galaxies at z ~ 0. Early secular evolution thus drives gas and stars into the central regions and can build up exponential disks and massive bulges, even without major mergers. Secular evolution along with increased efficiency of star formation at high surface densities may also help to account for the short time scales of the stellar buildup observed in massive galaxies at z ~ 2.

scholarly journals The star formation histories of the Magellanic Clouds

1991 ◽  
Vol 148 ◽  
pp. 138-138
Author(s):  
H. R. Butcher
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Local Group ◽  
High Redshift ◽  
Magellanic Clouds ◽  
Empirical Methods ◽  
Star Forming ◽  
Two Systems ◽  
The Galaxy ◽  
Star Formation Histories

Existing observations of the Magellanic Clouds suggest substantially different star-forming histories for the two systems. The reliability of this conclusion is discussed in the context of the uncertainties and age resolutions of various empirical methods of studying galaxy evolution. An attempt is also made to relate likely evolutionary scenarios for the Clouds to the histories of other Local Group systems, to the evolution seen in galaxies at high redshift, and to possible histories determined by interaction with the Galaxy.

scholarly journals The H i morphology and stellar properties of strongly barred galaxies: support for bar quenching in massive spirals

2020 ◽  
Vol 492 (4) ◽  
pp. 4697-4715 ◽  
Author(s):  
L Newnham ◽  
Kelley M Hess ◽  
Karen L Masters ◽  
Sandor Kruk ◽  
Samantha J Penny ◽  
...  
Keyword(s):  
Star Formation ◽  
Sloan Digital Sky Survey ◽  
Optical Data ◽  
Star Forming ◽  
Barred Galaxies ◽  
Stellar Properties ◽  
Open Question ◽  
Star Formation Histories ◽  
Gas Fractions ◽  
Disc Galaxies

ABSTRACT Galactic bars are able to affect the evolution of galaxies by redistributing their gas, possibly contributing to the cessation of star formation. Several recent works point to ‘bar quenching’ playing an important role in massive disc galaxies. We construct a sample of six gas-rich and strongly barred disc galaxies with resolved H i observations. This sample of galaxies, which we call H i-rich barred galaxies, was identified with the help of Galaxy Zoo to find galaxies hosting a strong bar, and the Arecibo Legacy Fast Arecibo L-band Feed Array blind H i survey to identify galaxies with a high H i content. The combination of strong bar and high gas fraction is rare, so this set of six galaxies is the largest sample of its type with resolved H i observations. We measure the gas fractions, H i morphology and kinematics, and use archival optical data from the Sloan Digital Sky Survey to reveal star formation histories and bar properties. The galaxies with the lowest gas fractions (still very high for their mass) show clear H i holes, dynamically advanced bars, and low star formation rates, while those with the highest gas fractions show little impact from their bar on the H i morphology, and are still actively star-forming. These galaxies support a picture in which the movement of gas by bars can lead to star formation quenching. How these unusual galaxies came to be is an open question.

scholarly journals Cosmological simulations of the same spiral galaxy: the impact of baryonic physics

2020 ◽  
Vol 501 (1) ◽  
pp. 62-77
Author(s):  
A Nuñez-Castiñeyra ◽  
E Nezri ◽  
J Devriendt ◽  
R Teyssier
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Galaxy Formation ◽  
Spiral Galaxy ◽  
Milky Way ◽  
Spiral Galaxies ◽  
Cosmological Simulations ◽  
Star Forming ◽  
Small Scales ◽  
The Impact

ABSTRACT The interplay of star formation (SF) and supernova (SN) feedback in galaxy formation is a key element for understanding galaxy evolution. Since these processes occur at small scales, it is necessary to have sub-grid models that recover their evolution and environmental effects at the scales reached by cosmological simulations. In this work, we present the results of the Mochima simulation, where we simulate the same spiral galaxy inhabiting a Milky Way (MW) size halo in a cosmological environment changing the sub-grid models for SN feedback and SF. We test combinations of the Schmidt law and a multifreefall based SF with delayed cooling feedback or mechanical feedback. We reach a resolution of 35 pc in a zoom-in box of 36 Mpc. For this, we use the code $\rm{\small RAMSES}$ with the implementation of gas turbulence in time and trace the local hydrodynamical features of the star-forming gas. Finally, we compare the galaxies at redshift 0 with global and interstellar medium observations in the MW and local spiral galaxies. The simulations show successful comparisons with observations. Nevertheless, diverse galactic morphologies are obtained from different numerical implementations. We highlight the importance of detailed modelling of the SF and feedback processes, especially for simulations with a resolution that start to reach scales relevant for molecular cloud physics. Future improvements could alleviate the degeneracies exhibited in our simulated galaxies under different sub-grid models.

scholarly journals Volumetric star formation laws of disc galaxies

2019 ◽  
Vol 622 ◽  
pp. A64 ◽  
Author(s):  
Cecilia Bacchini ◽  
Filippo Fraternali ◽  
Giuliano Iorio ◽  
Gabriele Pezzulli
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Formation Rate ◽  
Three Dimensional ◽  
Gas Content ◽  
Nearby Star ◽  
Star Forming ◽  
Good Tracer ◽  
Cold Star ◽  
Disc Galaxies

Star formation (SF) laws are fundamental relations between the gas content of a galaxy and its star formation rate (SFR) and play key roles in galaxy evolution models. In this paper, we present new empirical SF laws of disc galaxies based on volume densities. Following the assumption of hydrostatic equilibrium, we calculated the radial growth of the thickness of the gaseous discs in the combined gravitational potential of dark matter, stars, and gas for 12 nearby star-forming galaxies. This allowed us to convert the observed surface densities of gas and SFR into the deprojected volume densities. We found a tight correlation with slope in the range 1.3–1.9 between the volume densities of gas (HI+H2) and the SFR with a significantly smaller scatter than the surface-based (Kennicutt) law and no change in the slope over five orders of magnitude. This indicates that taking into account the radial increase of the thickness of galaxy discs is crucial to reconstruct their three-dimensional density profiles, in particular in their outskirts. Moreover, our result suggests that the break in the slope seen in the Kennicutt law is due to disc flaring rather than to a drop of the SF efficiency at low surface densities. Surprisingly, we discovered an unexpected correlation between the volume densities of HI and SFR, indicating that the atomic gas is a good tracer of the cold star-forming gas, especially in low density HI-dominated environments.

scholarly journals The effects of star formation history in the SFR–M* relation of H ii galaxies

2020 ◽  
Vol 500 (3) ◽  
pp. 3240-3253
Author(s):  
Amanda R Lopes ◽  
Eduardo Telles ◽  
Jorge Melnick
Keyword(s):  
Star Formation ◽  
Spectral Energy Distribution ◽  
Formation Rate ◽  
Star Formation History ◽  
Spectral Energy ◽  
Distribution Fitting ◽  
Good Tool ◽  
Star Forming ◽  
Additional Information ◽  
Star Formation Histories

ABSTRACT We discuss the implications of assuming different star formation histories (SFH) in the relation between star formation rate (SFR) and mass derived by the spectral energy distribution fitting (SED). Our analysis focuses on a sample of H ii galaxies, dwarf starburst galaxies spectroscopically selected through their strong narrow emission lines in SDSS DR13 at z &lt; 0.4, cross-matched with photometric catalogues from GALEX, SDSS, UKIDSS, and WISE. We modelled and fitted the SEDs with the code CIGALE adopting different descriptions of SFH. By adding information from different independent studies, we find that H ii galaxies are best described by episodic SFHs including an old (10 Gyr), an intermediate age (100−1000 Myr) and a recent population with ages &lt; 10 Myr. H ii galaxies agree with the SFR−M* relation from local star-forming galaxies, and only lie above such relation when the current SFR is adopted as opposed to the average over the entire SFH. The SFR−M* demonstrated not to be a good tool to provide additional information about the SFH of H ii galaxies, as different SFH present a similar behaviour with a spread of &lt;0.1 dex.

scholarly journals Modelling H2 and its effects on star formation using a joint implementation of gadget-3 and KROME

2021 ◽  
Vol 504 (2) ◽  
pp. 2325-2345
Author(s):  
Emanuel Sillero ◽  
Patricia B Tissera ◽  
Diego G Lambas ◽  
Stefano Bovino ◽  
Dominik R Schleicher ◽  
...  
Keyword(s):  
Star Formation ◽  
Formation Rate ◽  
Physical Parameters ◽  
Density Profiles ◽  
Star Forming ◽  
Chemical Enrichment ◽  
Numerical Resolution ◽  
Stellar Radiation ◽  
Wide Range ◽  
The Impact

ABSTRACT We present p-gadget3-k, an updated version of gadget-3, that incorporates the chemistry package krome. p-gadget3-k follows the hydrodynamical and chemical evolution of cosmic structures, incorporating the chemistry and cooling of H2 and metal cooling in non-equilibrium. We performed different runs of the same ICs to assess the impact of various physical parameters and prescriptions, namely gas metallicity, molecular hydrogen formation on dust, star formation recipes including or not H2 dependence, and the effects of numerical resolution. We find that the characteristics of the simulated systems, both globally and at kpc-scales, are in good agreement with several observable properties of molecular gas in star-forming galaxies. The surface density profiles of star formation rate (SFR) and H2 are found to vary with the clumping factor and resolution. In agreement with previous results, the chemical enrichment of the gas component is found to be a key ingredient to model the formation and distribution of H2 as a function of gas density and temperature. A star formation algorithm that takes into account the H2 fraction together with a treatment for the local stellar radiation field improves the agreement with observed H2 abundances over a wide range of gas densities and with the molecular Kennicutt–Schmidt law, implying a more realistic modelling of the star formation process.

scholarly journals Survey of ortho-H2D+ in high-mass star-forming regions

2020 ◽  
Vol 644 ◽  
pp. A34
Author(s):  
G. Sabatini ◽  
S. Bovino ◽  
A. Giannetti ◽  
F. Wyrowski ◽  
M. A. Órdenes ◽  
...  
Keyword(s):  
Star Formation ◽  
Formation Process ◽  
Strong Dependence ◽  
Cosmic Ray ◽  
High Mass ◽  
Clear Correlation ◽  
Mass Star ◽  
Large Sample ◽  
Star Forming ◽  
Star Forming Regions

Context. Deuteration has been suggested to be a reliable chemical clock of star-forming regions due to its strong dependence on density and temperature changes during cloud contraction. In particular, the H3+ isotopologues (e.g. ortho-H2D+) seem to act as good proxies of the evolutionary stages of the star formation process. While this has been widely explored in low-mass star-forming regions, in the high-mass counterparts only a few studies have been pursued, and the reliability of deuteration as a chemical clock remains inconclusive. Aims. We present a large sample of o-H2D+ observations in high-mass star-forming regions and discuss possible empirical correlations with relevant physical quantities to assess its role as a chronometer of star-forming regions through different evolutionary stages. Methods. APEX observations of the ground-state transition of o-H2D+ were analysed in a large sample of high-mass clumps selected from the ATLASGAL survey at different evolutionary stages. Column densities and beam-averaged abundances of o-H2D+ with respect to H2, X(o-H2D+), were obtained by modelling the spectra under the assumption of local thermodynamic equilibrium. Results. We detect 16 sources in o-H2D+ and find clear correlations between X(o-H2D+) and the clump bolometric luminosity and the dust temperature, while only a mild correlation is found with the CO-depletion factor. In addition, we see a clear correlation with the luminosity-to-mass ratio, which is known to trace the evolution of the star formation process. This would indicate that the deuterated forms of H3+ are more abundant in the very early stages of the star formation process and that deuteration is influenced by the time evolution of the clumps. In this respect, our findings would suggest that the X(o-H2D+) abundance is mainly affected by the thermal changes rather than density changes in the gas. We have employed these findings together with observations of H13CO+, DCO+, and C17O to provide an estimate of the cosmic-ray ionisation rate in a sub-sample of eight clumps based on recent analytical work. Conclusions. Our study presents the largest sample of o-H2D+ in star-forming regions to date. The results confirm that the deuteration process is strongly affected by temperature and suggests that o-H2D+ can be considered a reliable chemical clock during the star formation processes, as proved by its strong temporal dependence.

scholarly journals In pursuit of giants

2020 ◽  
Vol 644 ◽  
pp. A144
Author(s):  
D. Donevski ◽  
A. Lapi ◽  
K. Małek ◽  
D. Liu ◽  
C. Gómez-Guijarro ◽  
...  
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Galaxy Formation ◽  
Main Sequence ◽  
Stellar Mass ◽  
Starburst Galaxies ◽  
Analytical Models ◽  
Physical Parameters ◽  
Star Forming ◽  
Galaxy Populations

The dust-to-stellar mass ratio (Mdust/M⋆) is a crucial, albeit poorly constrained, parameter for improving our understanding of the complex physical processes involved in the production of dust, metals, and stars in galaxy evolution. In this work, we explore trends of Mdust/M⋆ with different physical parameters and using observations of 300 massive dusty star-forming galaxies detected with ALMA up to z ≈ 5. Additionally, we interpret our findings with different models of dusty galaxy formation. We find that Mdust/M⋆ evolves with redshift, stellar mass, specific star formation rates, and integrated dust size, but that evolution is different for main-sequence galaxies than it is for starburst galaxies. In both galaxy populations, Mdust/M⋆ increases until z ∼ 2, followed by a roughly flat trend towards higher redshifts, suggesting efficient dust growth in the distant universe. We confirm that the inverse relation between Mdust/M⋆ and M⋆ holds up to z ≈ 5 and can be interpreted as an evolutionary transition from early to late starburst phases. We demonstrate that the Mdust/M⋆ in starbursts reflects the increase in molecular gas fraction with redshift and attains the highest values for sources with the most compact dusty star formation. State-of-the-art cosmological simulations that include self-consistent dust growth have the capacity to broadly reproduce the evolution of Mdust/M⋆ in main-sequence galaxies, but underestimating it in starbursts. The latter is found to be linked to lower gas-phase metallicities and longer dust-growth timescales relative to observations. The results of phenomenological models based on the main-sequence and starburst dichotomy as well as analytical models that include recipes for rapid metal enrichment are consistent with our observations. Therefore, our results strongly suggest that high Mdust/M⋆ is due to rapid dust grain growth in the metal-enriched interstellar medium. This work highlights the multi-fold benefits of using Mdust/M⋆ as a diagnostic tool for: (1) disentangling main-sequence and starburst galaxies up to z ∼ 5; (2) probing the evolutionary phase of massive objects; and (3) refining the treatment of the dust life cycle in simulations.

scholarly journals Low Metallicity Galaxies at z ~ 0.7: Keys to the Origins of Metallicity Scaling Laws

2008 ◽  
Vol 4 (S255) ◽  
pp. 397-401
Author(s):  
David J. Rosario ◽  
Carlos Hoyos ◽  
David Koo ◽  
Andrew Phillips
Keyword(s):  
Star Formation ◽  
Emission Line ◽  
Galaxy Evolution ◽  
Scaling Laws ◽  
Temperature Sensitive ◽  
Star Forming ◽  
Low Metallicity ◽  
Emission Line Galaxies ◽  
Halo Masses ◽  
Stellar Masses

AbstractWe present a study of remarkably luminous and unique dwarf galaxies at redshifts of 0.5 < z < 0.7, selected from the DEEP2 Galaxy Redshift survey by the presence of the temperature sensitive [OIII]λ4363 emission line. Measurements of this important auroral line, as well as other strong oxygen lines, allow us to estimate the integrated oxygen abundances of these galaxies accurately without being subject to the degeneracy inherent in the standard R23 system used by most studies. [O/H] estimates range between 1/5–1/10 of the solar value. Not surprisingly, these systems are exceedingly rare and hence represent a population that is not typically present in local surveys such as SDSS, or smaller volume deep surveys such as GOODS.Our low-metallicity galaxies exhibit many unprecedented characteristics. With B-band luminosities close to L*, thse dwarfs lie significantly away from the luminosity-metallicity relationships of both local and intermediate redshift star-forming galaxies. Using stellar masses determined from optical and NIR photometry, we show that they also deviate strongly from corresponding mass-metallicity relationships. Their specific star formation rates are high, implying a significant burst of recent star formation. A campaign of high resolution spectroscopic follow-up shows that our galaxies have dynamical properties similar to local HII and compact emission line galaxies, but mass-to-light ratios that are much higher than average star-forming dwarfs.The low metallicities, high specific star formation rates, and small halo masses of our galaxies mark them as lower redshift analogs of Lyman-Break galaxies, which, at z ~ 2 are evolving onto the metallicity sequence that we observe in the galaxy population of today. In this sense, these systems offer fundamental insights into the physical processes and regulatory mechanisms that drive galaxy evolution in that epoch of major star formation and stellar mass assembly.

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