The structures of distant galaxies - III. The merger history of over 20 000 massive galaxies at<i>z</i>&lt; 1.2

Conselice, Christopher J.; Cui, Yang; Bluck, Asa F. L.

doi:10.1111/j.1365-2966.2009.14396.x

Cited by 183 publications

(289 citation statements)

References 62 publications

(325 reference statements)

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“…7.3. This is the first quantitative measurement of the minor merger rate using close pair statistics at these redshifts; 2. this trend is significantly different from the evolution of the major merger rate (μ ≥ 1/4) which we determine as increasing with redshift, in agreement with de Ravel et al (2009), and previous studies in the literature (e.g., Le Fèvre et al 2000;Conselice et al 2003Conselice et al , 2009López-Sanjuan et al 2009b;Bridge et al 2010); 3. the total merger rate (major + minor) is consistent either with a mild increase with redshift or with a constant R m ∼ 0.1 Gyr −1 .…”

Section: B Galaxiessupporting

confidence: 89%

The VIMOS VLT Deep Survey

López-Sanjuan

Fèvre

Ravel

et al. 2011

A&A

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Aims. The role of minor galaxy mergers in galaxy evolution, and in particular to mass assembly, remains an open question. In this work we measure the merger fraction, f m , of L B > ∼ L * B galaxies in the VVDS-Deep spectroscopic survey, and study its dependence on the B-band luminosity ratio the pair galaxies, μ ≡ L B,2 /L B,1 , focusing on minor mergers with 1/10 ≤ μ < 1/4, and on the rest-frame NUV − r colour of the principal galaxies. Methods. We use spectroscopic pairs with redshift z < ∼ 1 in the VVDS-Deep survey to define kinematical close pairs as those galaxies with a separation on the sky plane 5 h −1 kpc < r p ≤ r max p and a relative velocity Δv ≤ 500 km s −1 in redshift space. We vary r max p from 30 h −1 kpc to 100 h −1 kpc. We study f m in two redshift intervals and for several values of μ, from 1/2 to 1/10. We take μ ≥ 1/4 and 1/10 ≤ μ < 1/4 as major and minor mergers. Results. The merger fraction increases with z and its dependence on μ is well described by a power-law function, f m (≥μ) ∝ μ s . The value of s evolves from s = −0.60 ± 0.08 at z = 0.8 to s = −1.02 ± 0.13 at z = 0.5. The fraction of minor mergers for bright galaxies shows little evolution with redshift as a power-law (1+z) m with index m = −0.4±0.7 for the merger fraction and m = −0.5±0.7 for the merger rate, in contrast with the increase in the major merger fraction (m = 1.3 ± 0.5) and rate (m = 1.3 ± 0.6) for the same galaxies. We split our principal galaxies in red and blue, finding that i) f m is higher for red galaxies at every μ, ii) f red m does not evolve with z, with s = −0.79 ± 0.12 at 0.2 < z < 0.95, and iii) f blue m evolves dramatically: the major merger fraction of blue galaxies decreases by a factor of three with cosmic time, while the minor merger fraction of blue galaxies is roughly constant. Conclusions. Our results show that the mass of normal L B > ∼ L * B galaxies has grown by about 25% since z ∼ 1 because of the combined effects of minor and major mergers. The relative contribution of the mass growth by merging is ∼25% due to minor mergers and ∼75% due to major mergers. The relative effect of merging is more important for red than for blue galaxies, with red galaxies subject to 0.5 minor and 0.7 major mergers since z ∼ 1, which leads to a mass growth of ∼40% and a size increase by a factor of 2. Our results also suggest that, for blue galaxies, minor mergers likely lead to early-type spirals rather than elliptical galaxies. These results show that minor merging is a significant but not dominant mechanism contributing to the mass growth of galaxies in the last ∼8 Gyr.

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Section: B Galaxiessupporting

confidence: 89%

The VIMOS VLT Deep Survey

López-Sanjuan

Fèvre

Ravel

et al. 2011

A&A

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“…Note this is a different timescale from Equation (20) as we are now considering closer galaxies and a more advanced merger stage. However, R should be the same (for an equivalent sample) as galaxies would be conserved at all phases of the merging process (Conselice, Yang, & Bluck 2009). One expects both timescales to be of order 1 Gyr (Puech et al 2012) but both can vary by factors of 2-3 (Lotz et al 2008).…”

Section: The Merger Ratementioning

confidence: 99%

The Dawes Review 1: Kinematic Studies of Star-Forming Galaxies Across Cosmic Time

Glazebrook

2013

Publ. Astron. Soc. Aust.

132

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The last seven years have seen an explosion in the number of Integral Field galaxy surveys, obtaining resolved 2D spectroscopy, especially at high-redshift. These have taken advantage of the mature capabilities of 8-10 m class telescopes and the development of associated technology such as AO. Surveys have leveraged both high spectroscopic resolution enabling internal velocity measurements and high spatial resolution from AO techniques and sites with excellent natural seeing. For the first time, we have been able to glimpse the kinematic state of matter in young, assembling starforming galaxies and learn detailed astrophysical information about the physical processes and compare their kinematic scaling relations with those in the local Universe. Observers have measured disc galaxy rotation, merger signatures, and turbulence-enhanced velocity dispersions of gas-rich discs. Theorists have interpreted kinematic signatures of galaxies in a variety of ways (rotation, merging, outflows, and feedback) and attempted to discuss evolution vs. theoretical models and relate it to the evolution in galaxy morphology. A key point that has emerged from this activity is that substantial fractions of high-redshift galaxies have regular kinematic morphologies despite irregular photometric morphologies and this is likely due to the presence of a large number of highly gas-rich discs. There has not yet been a review of this burgeoning topic. In this first Dawes review, I will discuss the extensive kinematic surveys that have been done and the physical models that have arisen for young galaxies at high-redshift.

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“…8 of Genel et al (2009) and our numbers are consistent with these theoretical works. Finally, Conselice et al (2009) studied the merger history of a large number of galaxies for z < 1.2. Our results here are again in good agreement with those presented in their Fig.…”

Section: Merging Ratementioning

confidence: 99%

Shape and kinematics of elliptical galaxies: evolution due to merging at z ${<}$ 1.5

González-García¹,

Oñorbe²,

Domínguez-Tenreiro³

et al. 2009

A&A

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Aims. We investigate the evolution in the shape and kinematics of elliptical galaxies in a cosmological framework. Methods. We identified relaxed, elliptical-like objects (ELOs) at redshifts z = 0, z = 0.5, z = 1 and z = 1.5 within a set of hydrodynamic, self-consistent simulations completed for a concordance cosmological model. Results. The population of elliptical systems that we analysed evolve systematically with time becoming rounder in general by z = 0 and also more velocity dispersion supported. We found that this is due primarily to major dry mergers where only a modest amount of angular momentum is involved in the merger event. Despite the general trend, in a significant number of cases the merger event involves a relatively high amount of specific angular momentum, which causes the system in general to acquire higher rotational support and/or a more oblate shape. These evolutionary patterns persist when we study our systems in projection, in simulating true observations, and thus should be evident in future observations.

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The structures of distant galaxies - III. The merger history of over 20 000 massive galaxies atz< 1.2

Cited by 183 publications

References 62 publications

The VIMOS VLT Deep Survey

The VIMOS VLT Deep Survey

The Dawes Review 1: Kinematic Studies of Star-Forming Galaxies Across Cosmic Time

Shape and kinematics of elliptical galaxies: evolution due to merging at z ${<}$ 1.5

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