GEMS: Galaxy Evolution from Morphologies and SEDs

Rix, H. W.; Barden, M.; Beckwith, S.; Bell, Eric F.; Borch, Andrea; Caldwell, J. A. R.; Häußler, Boris; Jahnke, K.; Jogee, Shardha; McIntosh, Daniel H.; Meisenheimer, K.; Peng, Chien Y.; Sanchez, Sebastian Francisco Sanchez; Somerville, Rachel S.; Wisotzki, L.; Wolf, Christian

doi:10.1086/420885

Cited by 392 publications

(315 citation statements)

References 61 publications

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“…The inner part of our 34 ×33 field was observed for the GOODS programme (Giavalisco et al 2004) in the four bands BVIZ (F435W, F606W, F775W and F850LP) and the outer regions were observed for the GEMS project (Rix et al 2004) in V and Z (F606W and F850LP). From these data, thumbnail pictures for nearly every dropout candidate are created and examples are also shown in Figs.…”

Section: Observations With Other Telescopesmentioning

confidence: 72%

GaBoDS: the Garching-Bonn Deep Survey

Hildebrandt¹,

Bomans

Erben³

et al. 2005

A&A

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We present first results of our search for high-redshift galaxies in deep CCD mosaic images. As a pilot study for a larger survey, very deep images of the Chandra Deep Field South (CDFS), taken with WFI@MPG/ESO2.2m, are used to select large samples of 1070 U-band and 565 B-band dropouts with the Lyman-break method. The data of these Lyman-break galaxies are made public as an electronic table. These objects are good candidates for galaxies at z ∼ 3 and z ∼ 4 which is supported by their photometric redshifts. The distributions of apparent magnitudes and the clustering properties of the two populations are analysed, and they show good agreement to earlier studies. We see no evolution in the comoving clustering scale length from z ∼ 3 to z ∼ 4. The techniques presented here will be applied to a much larger sample of U-dropouts from the whole survey in near future.

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Section: Observations With Other Telescopesmentioning

confidence: 72%

GaBoDS: the Garching-Bonn Deep Survey

Hildebrandt¹,

Bomans

Erben³

et al. 2005

A&A

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“…We checked its optical morphology using HST imaging from the GEMS survey (Rix et al 2004) and confirm that it has an unresolved morphology with a PSF of ∼0.08 (diffraction limit in the z 850 band). The X-ray-to-optical flux ratio is low (log[ f 0.5−2 keV / f R ] = −1.8), confirming the stellar classification (see e.g.…”

Section: Sample Selectionmentioning

confidence: 99%

X-ray observations of sub-mm LABOCA galaxies in the eCDFS

Georgantopoulos

Rovilos

Comastri

2010

A&A

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We explore the X-ray properties of the 126 sub-mm galaxies (SMGs) of the LABOCA survey in the CDFS and the eCDFS regions. SMGs are believed to experience massive episodes of star formation. Our goal is to examine whether star formation coexists with AGN activity, determine the fraction of highly obscured AGN, and finally to obtain an idea of the dominant power mechanism in these sources. Using Spitzer and radio arcsecond positions for the SMGs, we find 14 sources with significant X-ray detections. For most of these there are only photometric redshifts available, with their median redshift at ∼2.3. Taking only the CDFS area into account that has the deepest X-ray observations, we estimate an X-ray AGN fraction of <26 ± 9% among SMGs. The X-ray spectral properties of the majority of the X-ray AGN that are associated with SMGs are consistent with high obscuration, >10 23 cm −2 , but there is no unambiguous evidence of Compton-thick sources. Detailed spectral energy distribution fittings show that the bulk of total IR luminosity originates in star forming processes, although a torus component is usually present. Finally, stacking analysis of the X-ray undetected SMGs reveals a signal in the soft (0.5-2 keV) and marginally in the hard (2-5 keV) X-ray bands. The hardness ratio of the stacked signal is relatively soft (−0.40 ± 0.10) corresponding to Γ ∼ 1.6. This argues against a high fraction of Compton-thick sources among the X-ray undetected SMGs.

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“…(15). Rix et al 2004) survey. We cannot compare directly the merger fractions from these two morphological studies with ours because of the different methodologies (e.g., Bridge et al 2010;Lotz et al 2011).…”

Section: The Merger Fraction Of the Global Massive Populationmentioning

confidence: 99%

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

131

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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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GEMS: Galaxy Evolution from Morphologies and SEDs

Cited by 392 publications

References 61 publications

GaBoDS: the Garching-Bonn Deep Survey

GaBoDS: the Garching-Bonn Deep Survey

X-ray observations of sub-mm LABOCA galaxies in the eCDFS

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

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