Colour gradients of low-redshift galaxies in the DESI Legacy Imaging Survey

Liao, Li-Wen; Cooper, Andrew

doi:10.48550/arxiv.2209.14166

Cited by 3 publications

(2 citation statements)

References 121 publications

(199 reference statements)

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“…Within this context, the orbits within which stars form remain untouched, thus, a positive stellar age and a rather steep negative stellar metallicity gradients are expected across the galaxy. This formation scenario explains the observed radial gradients of [M/H], [𝛼/Fe], reddening of colours (e.g., Peletier et al 1990;Liao & Cooper 2022) and line strength indices (e.g., Carollo et al 1993;Davies et al 1993;Trager et al 2000) in ETGs. Observations of Kobayashi & Arimoto (1999), in agreement with predictions from hydrodynamical simulations of Pipino et al (2008), show a slope range of -0.5 to -0.2, per decade of radius, for the stellar metallicity gradient (∇ [M/H] ) in early-type galaxies (ETGs) over a wide range of stellar mass.…”

Section: Introductionmentioning

confidence: 66%

On the accretion of a new group of galaxies on to Virgo – II. The effect of pre-processing on the stellar population content of dEs

Bidaran

Barbera

Pasquali

et al. 2022

Monthly Notices of the Royal Astronomical Society

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Using MUSE spectra, we investigate how pre-processing and accretion on to a galaxy cluster affect the integrated stellar population properties of dwarf early-type galaxies (dEs). We analyse a sample of nine dEs with stellar masses of $\rm \sim 10^9 \, M_\odot$, which were accreted (∼ 2-3 Gyr ago) on to the Virgo cluster as members of a massive galaxy group. We derive their stellar population properties, namely age, metallicity ([M/H]), and the abundance ratio of α elements ([α/Fe]), by fitting observed spectral indices with a robust, iterative procedure, and infer their star formation history (SFH) by means of full spectral fitting. We find that these nine dEs are more metal-poor (at the 2-3σ level) and significantly more α-enhanced than dEs in the Virgo and Coma clusters with similar stellar mass, cluster-centric distance, and infall time. Moreover, for six dEs, we find evidence for a recent episode of star formation during or right after the time of accretion on to Virgo. We interpret the high [α/Fe] of our sample of dEs as the result of the previous exposure of these galaxies to an environment hostile to star formation, and/or the putative short burst of star formation they underwent after infall into Virgo. Our results suggest that the stellar population properties of low-mass galaxies may be the result of the combined effect of pre-processing in galaxy groups and environmental processes (such as ram-pressure triggering star formation) acting during the early phases of accretion on to a cluster.

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Section: Introductionmentioning

confidence: 66%

On the accretion of a new group of galaxies on to Virgo – II. The effect of pre-processing on the stellar population content of dEs

Bidaran

Barbera

Pasquali

et al. 2022

Monthly Notices of the Royal Astronomical Society

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“…The spectroscopic redshifts of galaxies are obtained from the SDSS. Details about sample selection can be found in Liao & Cooper (2022).…”

Section: Introductionmentioning

confidence: 99%

Colour gradients of low-redshift galaxies in the DESI Legacy Imaging Survey

Liao

Cooper

2021

Proc. IAU

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Radial colour gradients within galaxies arise from gradients of stellar age, metallicity, and dust reddening. Large samples of colour gradients from wide-area imaging surveys can be used to constrain galaxy formation models. Here we measured colour gradients for low-redshift galaxies using photometry from the 9th DESI Legacy Imaging Survey (LS), which reaches r ∼ 24 over ∼14,000 deg2. We investigate empirical relationships between colour gradients, M*, and sSFR. We compared our results with the prediction of the Illustris TNG-100 simulation using SDSS mock images.

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On the accretion of a new group of galaxies onto Virgo – III. The stellar population radial gradients of dEs

Bidaran,

La Barbera,

Pasquali

et al. 2023

Monthly Notices of the Royal Astronomical Society

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Using MUSE data, we investigate the radial gradients of stellar population properties (namely age, [M/H], and the abundance ratio of α elements [α/Fe]) for a sample of nine dwarf early-type (dE) galaxies with log(M⋆/M⊙) ∼ 9.0 and an infall time onto the Virgo cluster of 2-3Gyr ago. We followed a similar approach as in Bidaran et al. (2022) to derive their stellar population properties and star formation histories (SFHs) through fitting observed spectral indices and full spectral fitting, respectively. We find that these nine dE galaxies have truncated [Mg/Fe]vs.[Fe/H] profiles than equally-massive Virgo dE galaxies with longer past infall times. Short profiles of three dE galaxies are the result of their intense star formation which has been quenched long before their accretion onto the Virgo cluster, possibly as a result of their group environment. In the remaining six dE galaxies, profiles mainly trace a recent episode of star burst within 0.4Re which results in higher light-weighted [α/Fe] values. The latter SFH peak can be due to ram pressure exerted by the Virgo cluster at the time of the accretion of the dE galaxies. Also, we show that younger, more metal-rich and less α-enhanced stellar populations dominate their inner regions (i.e., < 0.4Re) resulting in mainly flat ∇age, negative ∇[M/H] and positive ∇[α/Fe]. We find that with increasing log(σRe) of dE galaxies, ∇age and ∇[α/Fe] flatten, and the latter correlation persists even after including early-type galaxies up to log(σRe ∼ 2.5), possibly due to the more extended star formation activity in the inner regions of dEs, as opposed to more massive early-type galaxies.

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Colour gradients of low-redshift galaxies in the DESI Legacy Imaging Survey

Cited by 3 publications

References 121 publications

On the accretion of a new group of galaxies on to Virgo – II. The effect of pre-processing on the stellar population content of dEs

On the accretion of a new group of galaxies on to Virgo – II. The effect of pre-processing on the stellar population content of dEs

Colour gradients of low-redshift galaxies in the DESI Legacy Imaging Survey

On the accretion of a new group of galaxies onto Virgo – III. The stellar population radial gradients of dEs

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