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 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 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 < 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 < 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 <0.1 dex.

scholarly journals Pushing back the limits: detailed properties of dwarf galaxies in a ΛCDM universe

2018 ◽  
Vol 616 ◽  
pp. A96 ◽  
Author(s):  
Yves Revaz ◽  
Pascale Jablonka
Keyword(s):  
Star Formation ◽  
Local Group ◽  
Dwarf Galaxies ◽  
Mass Scale ◽  
Dwarf Spheroidal Galaxies ◽  
The Galaxy ◽  
Dynamical Simulations ◽  
Ursa Minor ◽  
Stellar Properties ◽  
Star Formation Histories

We present the results of a set of high-resolution chemo-dynamical simulations of dwarf galaxies in a ΛCDM cosmology. Out of an original (3.4 Mpc/h)3 cosmological box, a sample of 27 systems are re-simulated from z = 70 to z = 0 using a zoom-in technique. Gas and stellar properties are confronted to the observations in the greatest details: in addition to the galaxy global properties, we investigated the model galaxy velocity dispersion profiles, half-light radii, star formation histories, stellar metallicity distributions, and [Mg/Fe] abundance ratios. The formation and sustainability of the metallicity gradients and kinematically distinct stellar populations are also tackled. We show how the properties of six Local Group dwarf galaxies, NGC 6622, Andromeda II, Sculptor, Sextans, Ursa Minor and Draco are reproduced, and how they pertain to three main galaxy build-up modes. Our results indicate that the interaction with a massive central galaxy could be needed for a handful of Local Group dwarf spheroidal galaxies only, the vast majority of the systems and their variety of star formation histories arising naturally from a ΛCDM framework. We find that models fitting well the local Group dwarf galaxies are embedded in dark haloes of mass between 5 × 108 to a few 109 M⊙, without any missing satellite problem. We confirm the failure of the abundance matching approach at the mass scale of dwarf galaxies. Some of the observed faint however gas-rich galaxies with residual star formation, such as Leo T and Leo P, remain challenging. They point out the need of a better understanding of the UV-background heating.

scholarly journals A new method to derive star formation histories in dwarf galaxies

2018 ◽  
Vol 14 (S344) ◽  
pp. 267-270
Author(s):  
Marius Čeponis ◽  
Rima Stonkutė ◽  
Vladas Vansevičius
Keyword(s):  
Star Formation ◽  
New Method ◽  
Star Forming ◽  
Stellar Photometry ◽  
Star Forming Regions ◽  
Density Maps ◽  
Irregular Galaxies ◽  
Star Formation Histories ◽  
Dwarf Irregular Galaxies ◽  
Inside Out

AbstractWe present a new method to derive 2D star formation histories in dwarf irregular galaxies. Based on multicolor stellar photometry data we have found that in the Leo A galaxy during the last ∽400 Myr star formation was propagating according to the inside-out scenario. Star-forming regions have spread strongly asymmetrically from the center and their present day distribution correlates well with the Hi surface density maps.

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 The lifecycle of molecular clouds in nearby star-forming disc galaxies

2019 ◽  
Vol 493 (2) ◽  
pp. 2872-2909 ◽  
Author(s):  
Mélanie Chevance ◽  
J M Diederik Kruijssen ◽  
Alexander P S Hygate ◽  
Andreas Schruba ◽  
Steven N Longmore ◽  
...  
Keyword(s):  
Star Formation ◽  
Flux Ratio ◽  
Molecular Gas ◽  
H Ii Regions ◽  
Dynamical Processes ◽  
Nearby Star ◽  
Star Forming ◽  
Spatially Resolved ◽  
Stellar Feedback ◽  
Disc Galaxies

ABSTRACT It remains a major challenge to derive a theory of cloud-scale ($\lesssim100$ pc) star formation and feedback, describing how galaxies convert gas into stars as a function of the galactic environment. Progress has been hampered by a lack of robust empirical constraints on the giant molecular cloud (GMC) lifecycle. We address this problem by systematically applying a new statistical method for measuring the evolutionary timeline of the GMC lifecycle, star formation, and feedback to a sample of nine nearby disc galaxies, observed as part of the PHANGS-ALMA survey. We measure the spatially resolved (∼100 pc) CO-to-H α flux ratio and find a universal de-correlation between molecular gas and young stars on GMC scales, allowing us to quantify the underlying evolutionary timeline. GMC lifetimes are short, typically $10\!-\!30\,{\rm Myr}$, and exhibit environmental variation, between and within galaxies. At kpc-scale molecular gas surface densities $\Sigma _{\rm H_2}\ge 8\,\rm {M_\odot}\,{{\rm pc}}^{-2}$, the GMC lifetime correlates with time-scales for galactic dynamical processes, whereas at $\Sigma _{\rm H_2}\le 8\,\rm {M_\odot}\,{{\rm pc}}^{-2}$ GMCs decouple from galactic dynamics and live for an internal dynamical time-scale. After a long inert phase without massive star formation traced by H α (75–90 per cent of the cloud lifetime), GMCs disperse within just $1\!-\!5\,{\rm Myr}$ once massive stars emerge. The dispersal is most likely due to early stellar feedback, causing GMCs to achieve integrated star formation efficiencies of 4–10 per cent. These results show that galactic star formation is governed by cloud-scale, environmentally dependent, dynamical processes driving rapid evolutionary cycling. GMCs and H ii regions are the fundamental units undergoing these lifecycles, with mean separations of $100\!-\!300\,{{\rm pc}}$ in star-forming discs. Future work should characterize the multiscale physics and mass flows driving these lifecycles.

scholarly journals The star formation histories of galaxies in the Sloan Digital Sky Survey

2007 ◽  
Vol 378 (4) ◽  
pp. 1550-1564 ◽  
Author(s):  
Benjamin Panter ◽  
Raul Jimenez ◽  
Alan F. Heavens ◽  
Stephane Charlot
Keyword(s):  
Star Formation ◽  
Sloan Digital Sky Survey ◽  
Sky Survey ◽  
Star Formation Histories

scholarly journals A redshift-dependent IRX–β dust attenuation relation for TNG50 galaxies

2020 ◽  
Vol 497 (4) ◽  
pp. 4773-4794 ◽  
Author(s):  
Sebastian Schulz ◽  
Gergö Popping ◽  
Annalisa Pillepich ◽  
Dylan Nelson ◽  
Mark Vogelsberger ◽  
...  
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
Main Sequence ◽  
Infrared Excess ◽  
Star Forming ◽  
Dust Composition ◽  
Metal Ratio ◽  
Stellar Masses ◽  
Dust Attenuation ◽  
Star Formation Histories

ABSTRACT We study the relation between the UV slope, β, and the ratio between the infrared- and UV luminosities (IRX) of galaxies from TNG50, the latest installment of the IllustrisTNG galaxy formation simulations. We select 7280 star-forming main-sequence (SFMS) galaxies with stellar mass ≥109 M⊙ at redshifts 0 ≤ z ≤ 4 and perform radiative transfer with skirt to model effects of interstellar medium dust on the emitted stellar light. Assuming a Milky Way dust type and a dust-to-metal ratio of 0.3, we find that TNG50 SFMS galaxies generally agree with observationally derived IRX–β relations at z ≲ 1. However, we find a redshift-dependent systematic offset with respect to empirically derived local relations, with the TNG50 IRX–β relation shifting towards lower β and steepening at higher redshifts. This is partially driven by variations in the dust-uncorrected UV slope of galaxies, due to different star formation histories of galaxies selected at different cosmic epochs; we suggest the remainder of the effect is caused by differences in the effective dust attenuation curves of galaxies as a function of redshift. We find a typical galaxy-to-galaxy variation of 0.3 dex in infrared excess (IRX) at fixed β, correlated with intrinsic galaxy properties: galaxies with higher star formation rates, star formation efficiencies, gas metallicities and stellar masses exhibit larger IRX values. We demonstrate a degeneracy between stellar age, dust geometry, and dust composition: z = 4 galaxies with a Small Magellanic Cloud dust type follow the same IRX–β relation as low-redshift galaxies with MW dust. We provide a redshift-dependent fitting function for the IRX–β relation for MW dust based on our models.

scholarly journals Stellar populations across galaxy bars in the MUSE TIMER project

2020 ◽  
Vol 637 ◽  
pp. A56 ◽  
Author(s):  
Justus Neumann ◽  
Francesca Fragkoudi ◽  
Isabel Pérez ◽  
Dimitri A. Gadotti ◽  
Jesús Falcón-Barroso ◽  
...  
Keyword(s):  
Star Formation ◽  
Major Axis ◽  
Stellar Populations ◽  
Barred Galaxies ◽  
Chemical Enrichment ◽  
Spatially Resolved ◽  
Stellar Ages ◽  
Hydrodynamical Simulations ◽  
Inner Region ◽  
Star Formation Histories

Stellar populations in barred galaxies save an imprint of the influence of the bar on the host galaxy’s evolution. We present a detailed analysis of star formation histories (SFHs) and chemical enrichment of stellar populations in nine nearby barred galaxies from the TIMER project. We used integral field observations with the MUSE instrument to derive unprecedented spatially resolved maps of stellar ages, metallicities, [Mg/Fe] abundances, and SFHs, as well as Hα as a tracer of ongoing star formation. We find a characteristic V-shaped signature in the SFH that is perpendicular to the bar major axis, which supports the scenario where intermediate-age stars (∼2 − 6 Gyr) are trapped on more elongated orbits shaping a thinner part of the bar, while older stars (> 8 Gyr) are trapped on less elongated orbits shaping a rounder and thicker part of the bar. We compare our data to state-of-the-art cosmological magneto-hydrodynamical simulations of barred galaxies and show that such V-shaped SFHs arise naturally due to the dynamical influence of the bar on stellar populations with different ages and kinematic properties. Additionally, we find an excess of very young stars (< 2 Gyr) on the edges of the bars, predominantly on the leading side, thus confirming typical star formation patterns in bars. Furthermore, mass-weighted age and metallicity gradients are slightly shallower along the bar than in the disc, which is likely due to orbital mixing in the bar. Finally, we find that bars are mostly more metal-rich and less [Mg/Fe]-enhanced than the surrounding discs. We interpret this as a signature that the bar quenches star formation in the inner region of discs, usually referred to as star formation deserts. We discuss these results and their implications on two different scenarios of bar formation and evolution.

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.

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