Cosmic Variance and Its Effect on the Luminosity Function Determination in Deep High‐<i>z</i>Surveys

Trenti, Michele; Stiavelli, M.

doi:10.1086/528674

Cited by 363 publications

(384 citation statements)

References 46 publications

(94 reference statements)

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“…In the case of a cluster field, we computed the effective volume covered by this survey in a similar manner as in Coe et al (2015) and using a mask of the bright objects in the cluster core. -Error bars include statistical uncertainties and cosmic variance computed using the integration of a two-point correlation function over the volume explored by our survey (Trenti & Stiavelli 2008).…”

Section: Methodsmentioning

confidence: 99%

Frontier Fields: Combining HST, VLT, andSpitzerdata to explore thez~ 8 Universe behind the lensing cluster MACSJ0416.1−2403

Laporte

Streblyanska

Kim

et al. 2015

A&A

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Context. The Hubble Space Telescope (HST) Frontier Fields (HFFs) project started at the end of 2013 with the aim of providing extremely deep images of six massive galaxy clusters. One of the main goals of this program is to push several telescopes to their limits to provide the best current view of the earliest stages of the Universe. The analysis of the initial data has already demonstrated the huge capabilities of the program. Aims. We present a detailed analysis of z ∼ 8 objects behind the HFFs lensing cluster, MACSJ0416.1-2403, combining 0.3−1.6 µm imaging from HST, ground-based K s imaging from VLT HAWK-I, and 3.6 µm and 4.5 µm Spitzer Space Telescope. The images probe to 5σ depths of ≈29 AB for HST, 25.6 AB for HAWK-I, and ≈0.310 and 0.391 µJy at 3.6 and 4.5 µm, respectively. With these datasets, we assess the photometric properties of z ∼ 8 galaxies in this field, as well as their distribution in luminosity, to unprecedented sensitivity. Methods. We applied the classical Lyman break (LB) technique, which combines non detection criteria in bands blueward of the Lyman break at z ∼ 8 and color-selection in bands redward of the break. To avoid contamination by mid-z interlopers, we required a strong break between optical and near-infrared data. We determined the photometric properties of z ∼ 8 selected candidates using spectral energy distribution (SED)-fitting with standard library templates. The luminosity function at z ∼ 8 is computed using a Monte-Carlo method taking advantage of the SED-fitting results. A piece of cautionary information is gleaned from new deep optical photometry of a previously identified z ∼ 8 galaxy in this cluster, which is now firmly detected as a mid-z interloper with a strong ≈1.5 mag Balmer break (between F606W and F125W). Using the SED of this interloper, we estimated the contamination rate of our MACSJ0416.1−2403 sample, and that of previous samples in Abell 2744 that were based on HFF data, we highlight the dangers of pushing the LB technique too close to the photometry limits. Results. Our selection reliably recovers four objects with m F160W ranging from 26.0 to 27.9 AB that are located in modestamplification regions (µ < 2.4). Two of the objects display a secondary break between the IRAC 3.6 µm and 4.5 µm bands, which could be associated to the Balmer break or emission lines at z ∼ 8. The SED-fitting analysis suggests that all of these objects favor high-z solutions with no reliable secondary solutions. The candidates generally have star formation rates around ∼10 M /yr and sizes ranging from 0.2 to 0.5 kpc, which agrees well with previous observations and expectations for objects in the early Universe. The sample size and luminosity distribution are consistent with previous findings.

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Section: Methodsmentioning

confidence: 99%

Frontier Fields: Combining HST, VLT, andSpitzerdata to explore thez~ 8 Universe behind the lensing cluster MACSJ0416.1−2403

Laporte

Streblyanska

Kim

et al. 2015

A&A

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“…Our analysis, in which we assign the same distance modulus to all galaxies with z phot < 0.3 complicates an estimate of this cosmic variance, since the basic recipes by e.g. Trenti & Stiavelli (2008), Moster et al (2011) cannot be applied. We do however make an empirical estimate based on catalogues from the 4 spatially independent CFHT Legacy Survey Deep fields Hildebrandt et al 2009), which each cover an un-masked area of about 0.8 deg 2 .…”

Section: Statistical Background Subtractionmentioning

confidence: 99%

Evidence for the inside-out growth of the stellar mass distribution in galaxy clusters sincez~1

Burg

Hoekstra

Muzzin

et al. 2015

A&A

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We study the radial number density and stellar mass density distributions of satellite galaxies in a sample of 60 massive clusters at 0.04 < z < 0.26 selected from the Multi-Epoch Nearby Cluster Survey (MENeaCS) and the Canadian Cluster Comparison Project (CCCP). In addition to ∼10 000 spectroscopically confirmed member galaxies, we use deep ugri-band imaging to estimate photometric redshifts and stellar masses, and then statistically subtract fore-and background sources using data from the COSMOS survey. We measure the galaxy number density and stellar mass density distributions in logarithmically spaced bins over 2 orders of magnitude in radial distance from the BCGs. For projected distances in the range 0.1 < R/R 200 < 2.0, we find that the stellar mass distribution is well-described by an NFW profile with a concentration of c = 2.03 ± 0.20. However, at smaller radii we measure a significant excess in the stellar mass in satellite galaxies of about 10 11 M per cluster, compared to these NFW profiles. We do obtain good fits to generalised NFW profiles with free inner slopes and to Einasto profiles. To examine how clusters assemble their stellar mass component over cosmic time, we compare this local sample to the GCLASS cluster sample at z ∼ 1, which represents the approximate progenitor sample of the low-z clusters. This allows for a direct comparison, which suggests that the central parts (R < 0.4 Mpc) of the stellar mass distributions of satellites in local galaxy clusters are already in place at z ∼ 1, and contain sufficient excess material for further BCG growth. Evolving towards z = 0, clusters appear to assemble their stellar mass primarily onto the outskirts, making them grow in an inside-out fashion.

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“…Various models to account for the effects of cosmic variance exist in the literature. Trenti & Stiavelli (2008) have developed a model that is offered as an on-line calculator. From this model and assuming a one-to-one correspondence between dark halos and LAEs, we obtain a value of ∼28% for the cosmic variance.…”

Section: Variancementioning

confidence: 99%

Limits on the luminosity function of Lyαemitters atz= 7.7

Hibon

Cuby

Willis

et al. 2010

A&A

101

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Aims. The Lyα luminosity function (LF) of high-redshift Lyα emitters (LAEs) is one of the few observables of the re-ionization epoch accessible with 8-10 m class telescopes. The evolution of the LAE LF with redshift is dependent upon the physical evolution of LAEs and the ionisation state of the Universe towards the end of the Dark Ages. Methods. We performed a narrow-band imaging program at 1.06 μm using CFHT/WIRCam. The observations target Lyα emitters at redshift z ∼ 7.7 in the CFHT-LS D1 field. From these observations we derived a photometric sample of 7 LAE candidates at z ∼ 7.7. Results. We derive luminosity functions for the full sample of seven objects and for subsamples of four objects. Assuming the brightest objects in our sample are real, we find that the resulting luminosity function is not consistent with previous work at lower redshifts. More definitive conclusions will require spectroscopic confirmation.

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Cosmic Variance and Its Effect on the Luminosity Function Determination in Deep High‐zSurveys

Cited by 363 publications

References 46 publications

Frontier Fields: Combining HST, VLT, andSpitzerdata to explore thez~ 8 Universe behind the lensing cluster MACSJ0416.1−2403

Frontier Fields: Combining HST, VLT, andSpitzerdata to explore thez~ 8 Universe behind the lensing cluster MACSJ0416.1−2403

Evidence for the inside-out growth of the stellar mass distribution in galaxy clusters sincez~1

Limits on the luminosity function of Lyαemitters atz= 7.7

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