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Title: Exploring a new definition of the green valley and its implications

Abstract

ABSTRACT The distribution of galaxies on a colour–magnitude diagram reveals a bimodality, featuring a passively evolving red sequence and a star-forming blue cloud. The region between these two, the green valley (GV), represents a fundamental transition where quenching processes operate. We exploit an alternative definition of the GV using the 4000 Å break strength, an indicator that is more resilient than colour to dust attenuation. We compare and contrast our GV definition with the traditional one, based on dust-corrected colour, making use of data from the Sloan Digital Sky Survey. Our GV selection – that does not need a dust correction and thus does not carry the inherent systematics – reveals very similar trends regarding nebular activity (star formation, AGN, quiescence) to the standard dust-corrected 0.1(g − r). By use of high-SNR stacked spectra of the quiescent GV subsample, we derive the simple stellar population (SSP) age difference across the GV, a rough proxy of the quenching time-scale (Δt). We obtain an increasing trend with velocity dispersion (σ), from Δt ∼ 1.5 Gyr at σ = 100 km s−1, up to 3.5 Gyr at σ = 200 km s−1, followed by a rapid decrease in the most massive GV galaxies (Δt ∼ 1 Gyr at σ = 250 km s−1), suggesting two different modes of quenching, or the presence ofmore » an additional channel (rejuvenation).« less

Authors:
 [1]; ORCiD logo [2]; ORCiD logo [3]
  1. Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking, Surrey RH5 6NT, UK
  2. Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK, Instituto de Astrofísica de Canarias, Calle Vía Láctea s/n, E-38205 La Laguna, Tenerife, Spain, Departamento de Astrofísica, Universidad de La Laguna (ULL), E-38206 La Laguna, Tenerife, Spain
  3. Institut d’Astrophysique de Paris (UMR 7095: CNRS & UPMC), 98 bis Bd Arago, F-75014 Paris, France, Sub-department of Astrophysics, University of Oxford, Keble Road, Oxford OX1 3RH, UK, Department of Physics and Astronomy, The Johns Hopkins University Homewood Campus, Baltimore, MD 21218, USA
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1543034
Resource Type:
Published Article
Journal Name:
Monthly Notices of the Royal Astronomical Society: Letters
Additional Journal Information:
Journal Name: Monthly Notices of the Royal Astronomical Society: Letters Journal Volume: 488 Journal Issue: 1; Journal ID: ISSN 1745-3925
Publisher:
Oxford University Press
Country of Publication:
United Kingdom
Language:
English

Citation Formats

Angthopo, James, Ferreras, Ignacio, and Silk, Joseph. Exploring a new definition of the green valley and its implications. United Kingdom: N. p., 2019. Web. doi:10.1093/mnrasl/slz106.
Angthopo, James, Ferreras, Ignacio, & Silk, Joseph. Exploring a new definition of the green valley and its implications. United Kingdom. doi:10.1093/mnrasl/slz106.
Angthopo, James, Ferreras, Ignacio, and Silk, Joseph. Thu . "Exploring a new definition of the green valley and its implications". United Kingdom. doi:10.1093/mnrasl/slz106.
@article{osti_1543034,
title = {Exploring a new definition of the green valley and its implications},
author = {Angthopo, James and Ferreras, Ignacio and Silk, Joseph},
abstractNote = {ABSTRACT The distribution of galaxies on a colour–magnitude diagram reveals a bimodality, featuring a passively evolving red sequence and a star-forming blue cloud. The region between these two, the green valley (GV), represents a fundamental transition where quenching processes operate. We exploit an alternative definition of the GV using the 4000 Å break strength, an indicator that is more resilient than colour to dust attenuation. We compare and contrast our GV definition with the traditional one, based on dust-corrected colour, making use of data from the Sloan Digital Sky Survey. Our GV selection – that does not need a dust correction and thus does not carry the inherent systematics – reveals very similar trends regarding nebular activity (star formation, AGN, quiescence) to the standard dust-corrected 0.1(g − r). By use of high-SNR stacked spectra of the quiescent GV subsample, we derive the simple stellar population (SSP) age difference across the GV, a rough proxy of the quenching time-scale (Δt). We obtain an increasing trend with velocity dispersion (σ), from Δt ∼ 1.5 Gyr at σ = 100 km s−1, up to 3.5 Gyr at σ = 200 km s−1, followed by a rapid decrease in the most massive GV galaxies (Δt ∼ 1 Gyr at σ = 250 km s−1), suggesting two different modes of quenching, or the presence of an additional channel (rejuvenation).},
doi = {10.1093/mnrasl/slz106},
journal = {Monthly Notices of the Royal Astronomical Society: Letters},
number = 1,
volume = 488,
place = {United Kingdom},
year = {2019},
month = {7}
}

Journal Article:
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