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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 »
- Authors:
-
[2];
[3]
- Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking, Surrey RH5 6NT, UK
- 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
- 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}
}
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