The XXL Survey: XXX. Characterisation of the XLSSsC N01 supercluster and analysis of the galaxy stellar populations
Artikel i vetenskaplig tidskrift, 2018

Context. Superclusters form from the largest enhancements in the primordial density perturbation field and extend for tens of Mpc, tracing the large-scale structure of the Universe. X-ray detections and systematic characterisations of superclusters and the properties of their galaxies have only been possible in the last few years. Aims. We characterise XLSSsC N01, a rich supercluster at z ∼ 0.3 detected in the XXL Survey, composed of X-ray clusters of different virial masses and X-ray luminosities. As one of the first studies on this topic, we investigate the stellar populations of galaxies in different environments in the supercluster region. Methods. We study a magnitude-limited (r ≤ 20) and a mass-limited sample (log(M ∗ Mo) ≥ 10.8) of galaxies in the virialised region and in the outskirts of 11 XLSSsC N01 clusters, in high-density field regions, and in the low-density field. We compute the stellar population properties of galaxies using spectral energy distribution (SED) and spectral fitting techniques, and study the dependence of star formation rates (SFR), colours, and stellar ages on environment. Results. For r ≤ 20, the fraction of star-forming/blue galaxies, computed either from the specific-SFR (sSFR) or rest-frame colour, shows depletion within the cluster virial radii, where the number of galaxies with log (sSFR/ yr-1) > -12 and with (g - r) restframe < 0.6 is lower than in the field. For log(M ∗ Mo) ≥ 10.8, no trends with environment emerge, as massive galaxies are mostly already passive in all environments. No differences among low- and high-density field members and cluster members emerge in the sSFR-mass relation in the mass-complete regime. Finally, the luminosity-weighted age-mass relation of the passive populations within cluster virial radii show signatures of recent environmental quenching. Conclusions. The study of luminous and massive galaxies in this supercluster shows that while environment has a prominent role in determining the fractions of star-forming/blue galaxies, its effects on the star formation activity in star-forming galaxies are negligible.

galaxies: evolution

galaxies: star formation

X-rays: galaxies: clusters

galaxies: groups: general

galaxies: stellar content

large-scale structure of Universe


V. Guglielmo

Osservatorio Astronomico di Padova

Laboratoire d'Astrophysique de Marseille


B. M. Poggianti

Osservatorio Astronomico di Padova

B. Vulcani

University of Melbourne

Osservatorio Astronomico di Padova

A. Moretti

Osservatorio Astronomico di Padova

J. Fritz

Universidad Nacional Autonoma de Mexico

F. Gastaldello

Istituto nazionale di astrofisica (INAF)

C. Adami

Laboratoire d'Astrophysique de Marseille

C. Caretta

Universidad de Guanajuato

J. Willis

University of Bristol

E. Koulouridis

Université Paris-Saclay

M. E. Ramos-Ceja

Universität Bonn

P. Giles

University of Bristol

I. Baldry

Liverpool John Moores University

M. Birkinshaw

University of Bristol

A. Bongiorno

Osservatorio Astronomico di Roma

M. Brown

Monash University

L. Chiappetti

Istituto nazionale di astrofisica (INAF)

S. Driver

University of St Andrews

University of Western Australia

A. Elyiv

Universita di Bologna

Main Astronomical Observatory Nasu

A. E. Evrard

University of Michigan

M. Grootes

European Space Research and Technology Centre (ESA ESTEC)

L. Guennou

University of KwaZulu-Natal

A. Hopkins

Australian Astronomical Observatory

Cathy Horellou

Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik, Extragalaktisk astrofysik

A. Iovino

Osservatorio Astronomico di Brera

S. Maurogordato

Université Nice Sophia Antipolis (UNS)

M. Owers

Macquarie University

Australian Astronomical Observatory

F. Pacaud

Universität Bonn

S. Paltani

Université de Genève

M. Pierre

Université Paris-Saclay

M. Plionis

National Observatory of Athens

Aristotelio Panepistimio Thessalonikis

T. J. Ponman

University of Birmingham

A. Robotham

University of Western Australia

T. Sadibekova

Uzbekistan Academy of Sciences

V. Smolcic

Sveučilište u Zagrebu

R. Tuffs

European Space Research and Technology Centre (ESA ESTEC)

Cristian Vignali

Osservatorio Astronomico Di Bologna

Universita di Bologna

Astronomy and Astrophysics

0004-6361 (ISSN) 1432-0746 (eISSN)

Vol. 620 A15



Astronomi, astrofysik och kosmologi




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