Galaxies in X-Ray Groups. I. Robust Membership Assignment and the Impact of Group Environments on Quenching

George, Matthew R.; Leauthaud, Alexie; Bundy, Kevin; Finoguenov, A.; Tinker, Jeremy L.; Lin, Yen-Ting; Mei, S.; Kneib, Jean-Paul; Aussel, H.; Behroozi, Peter; Busha, Michael T.; Capak, P.; Coccato, L.; Covone, G.; Fauré, C.; Fiorenza, Stephanie; Ilbert, O.; Floc’h, E. Le; Koekemoer, Anton M.; Tanaka, Masayuki; Wechsler, Risa H.; Wolk, M.

doi:10.1088/0004-637x/742/2/125

Cited by 137 publications

(308 citation statements)

References 132 publications

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“…2.1), explaining their high photometric redshift errors. Similar trends in the COSMOS photometric redshift errors were found by George et al (2011). In Sect.…”

Section: Dependence Of the Photometric Errors On Stellar Masssupporting

confidence: 84%

The dominant role of mergers in the size evolution of massive early-type galaxies sincez ~ 1

López-Sanjuan

Fèvre

Ilbert

et al. 2012

A&A

133

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Aims. The role of galaxy mergers in massive galaxy evolution, and in particular to mass assembly and size growth, remains an open question. In this paper we measure the merger fraction and rate, both minor and major, of massive early-type galaxies (M ≥ 10 11 M ) in the COSMOS field, and study their role in mass and size evolution. Methods. We used the 30-band photometric catalogue in COSMOS, complemented with the spectroscopy of the zCOSMOS survey, to define close pairs with a separation on the sky plane 10 h −1 kpc ≤ r p ≤ 30 h −1 kpc and a relative velocity Δv ≤ 500 km s −1 in redshift space. We measured both major (stellar mass ratio μ ≡ M ,2 /M ,1 ≥ 1/4) and minor (1/10 ≤ μ < 1/4) merger fractions of massive galaxies, and studied their dependence on redshift and on morphology (early types vs. late types). Results. The merger fraction and rate of massive galaxies evolves as a power-law (1 + z) n , with major mergers increasing with redshift, n MM = 1.4, and minor mergers showing little evolution, n mm ∼ 0. When split by their morphology, the minor merger fraction for early-type galaxies (ETGs) is higher by a factor of three than that for late-type galaxies (LTGs), and both are nearly constant with redshift. The fraction of major mergers for massive LTGs evolves faster (n LT MM ∼ 4) than for ETGs (n ET MM = 1.8). Conclusions. Our results show that massive ETGs have undergone 0.89 mergers (0.43 major and 0.46 minor) since z ∼ 1, leading to a mass growth of ∼30%. We find that μ ≥ 1/10 mergers can explain ∼55% of the observed size evolution of these galaxies since z ∼ 1. Another ∼20% is due to the progenitor bias (younger galaxies are more extended) and we estimate that very minor mergers (μ < 1/10) could contribute with an extra ∼20%. The remaining ∼5% should come from other processes (e.g., adiabatic expansion or observational effects). This picture also reproduces the mass growth and the velocity dispersion evolution of these galaxies. We conclude from these results, and after exploring all the possible uncertainties in our picture, that merging is the main contributor to the size evolution of massive ETGs at z 1, accounting for ∼50−75% of that evolution in the last 8 Gyr. Nearly half of the evolution due to mergers is related to minor (μ < 1/4) events.

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“…2.1), explaining their high photometric redshift errors. Similar trends in the COSMOS photometric redshift errors were found by George et al (2011). In Sect.…”

Section: Dependence Of the Photometric Errors On Stellar Masssupporting

confidence: 84%

The dominant role of mergers in the size evolution of massive early-type galaxies sincez ~ 1

López-Sanjuan

Fèvre

Ilbert

et al. 2012

A&A

133

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“…George et al 2011). Given our photometric redshift statistical uncertainties, our cross-correlation estimator provides a more robust (although noisier) satellite number estimate.…”

Section: Stellar Fractionmentioning

confidence: 99%

The XXL Survey

Eckert

Ettori

Coupon

et al. 2016

A&A

115

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Traditionally, galaxy clusters have been expected to retain all the material accreted since their formation epoch. For this reason, their matter content should be representative of the Universe as a whole, and thus their baryon fraction should be close to the Universal baryon fraction Ω b /Ω m . We make use of the sample of the 100 brightest galaxy clusters discovered in the XXL Survey to investigate the fraction of baryons in the form of hot gas and stars in the cluster population. Since it spans a wide range of mass (10 13 −10 15 M ) and redshift (0.05−1.1) and benefits from a large set of multiwavelength data, the XXL-100-GC sample is ideal for measuring the global baryon budget of massive halos. We measure the gas masses of the detected halos and use a mass-temperature relation directly calibrated using weak-lensing measurements for a subset of XXL clusters to estimate the halo mass. We find that the weak-lensing calibrated gas fraction of XXL-100-GC clusters is substantially lower than was found in previous studies using hydrostatic masses. Our best-fit relation between gas fraction and mass reads f gas,500 = 0.055 +0.007 −0.006 M 500 /10 14 M 0.21 +0.11 −0.10 . The baryon budget of galaxy clusters therefore falls short of the Universal baryon fraction by about a factor of two at r 500,MT . Our measurements require a hydrostatic bias 1 − b = M X /M WL = 0.72 +0.08 −0.07 to match the gas fraction obtained using lensing and hydrostatic equilibrium, which holds independently of the instrument considered. Comparing our gas fraction measurements with the expectations from numerical simulations, we find that our results favour an extreme feedback scheme in which a significant fraction of the baryons are expelled from the cores of halos. This model is, however, in contrast with the thermodynamical properties of observed halos, which might suggest that weak-lensing masses are overestimated. In light of these results, we note that a mass bias 1 − b = 0.58 as required to reconcile Planck cosmic microwave background and cluster counts should translate into an even lower baryon fraction, which poses a major challenge to our current understanding of galaxy clusters.

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“…We use the X-ray group catalogs from the AEGIS field (Erfanianfar et al 2013), the COSMOS field (Finoguenov et al 2007;George et al 2011), including all spectroscopic observations, available within the collaboration. We also use all spectroscopic data of groups in our catalog provided by the VVDS data and Adami et al (2011).…”

Section: Contamination Of Group Membershipmentioning

confidence: 99%

Mining the gap: evolution of the magnitude gap in X-ray galaxy groups from the 3-square-degree XMM coverage of CFHTLS

Gozaliasl¹,

Finoguenov²,

Khosroshahi³

et al. 2014

A&A

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We present a catalog of 129 X-ray galaxy groups, covering a redshift range 0.04 < z < 1.23, selected in the ∼3 deg 2 part of the CFHTLS W1 field overlapping XMM observations performed under the XMM-LSS project. We carry out a statistical study of the redshift evolution out to redshift one of the magnitude gap between the first and the second brightest cluster galaxies of a well defined mass-selected group sample. We find that the slope of the relation between the fraction of groups and the magnitude gap steepens with redshift, indicating a larger fraction of fossil groups at lower redshifts. We find that 22.2 ± 6% of our groups at z ≤ 0.6 are fossil groups. We compare our results with the predictions of three semi-analytic models based on the Millennium simulation. The intercept of the relation between the magnitude of the brightest galaxy and the value of magnitude gap becomes brighter with increasing redshift. This trend is steeper than the model predictions which we attribute to the younger stellar age of the observed brightest cluster galaxies. This trend argues in favor of stronger evolution of the feedback from active galactic nuclei at z < 1 compared to the models. The slope of the relation between the magnitude of the brightest cluster galaxy and the value of the gap does not evolve with redshift and is well reproduced by the models, indicating that the tidal galaxy stripping, put forward as an explanation of the occurrence of the magnitude gap, is both a dominant mechanism and sufficiently well modeled.

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Galaxies in X-Ray Groups. I. Robust Membership Assignment and the Impact of Group Environments on Quenching

Cited by 137 publications

References 132 publications

The dominant role of mergers in the size evolution of massive early-type galaxies sincez ~ 1

The dominant role of mergers in the size evolution of massive early-type galaxies sincez ~ 1

The XXL Survey

Mining the gap: evolution of the magnitude gap in X-ray galaxy groups from the 3-square-degree XMM coverage of CFHTLS

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