A framework for simultaneously measuring field densities and the high-z luminosity function

Trapp, Adam; Furlanetto, Steven R.; Yang, Jinghong

doi:10.1093/mnras/stab3801

Cited by 5 publications

(8 citation statements)

References 47 publications

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“…We fit a Schechter luminosity function to galaxy catalogs using a Bayesian fitting framework. This framework is described in detail in section 2.1 and 2.2 of Trapp et al (2022), but we summarize it here.…”

Section: Fitting the Luminosity Functionmentioning

confidence: 99%

“…From Trapp et al (2022), the log likelihood is lnL ∝ where the first sum is over each field, and the second sum is over each source in the i th field. Also, ni,exp is the number of sources expected in the i th field given the average luminosity function parameters φavg and the local density δi.…”

Section: Fieldmentioning

confidence: 99%

“…Unfortunately, sampling the posterior with many sub-fields can still be costly. To alleviate this limitation, in Trapp et al (2022) we developed a method to combine many different fields into "composite" fields with a single density parameter and an "effective" cosmic variance value, with the treatment of the combination depending on whether the fields are contiguous or treated as independent. In this work, we combine the following groups of fields into "composite" fields:…”

Section: Data Setsmentioning

confidence: 99%

“…In Trapp et al (2022), we developed a framework that simultaneously measures field densities and the high-z luminosity function given a set of galaxy surveys. Unlike the standard approach to estimating luminosity functions, which acknowledges the existence of cosmic variance but does not attempt to model it, our new framework uses Bayesian statistics to fold in a comprehensive model of cosmic variance (Trapp & Furlanetto 2020) and its effect on the galaxy population (which changes the shape of the luminosity function, see Fig-ure 1).…”

Section: Introductionmentioning

confidence: 99%

“…In section 2, we describe the data sets we use, briefly summarize the framework from Trapp et al (2022), and describe the new method of measuring environments. In sections 3 and 4, we present our new measurements of the z = 6-8 luminosity function and field densities.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

A joint measurement of galaxy luminosity functions and large-scale field densities during the Epoch of Reionization

Trapp

Furlanetto

2022

Monthly Notices of the Royal Astronomical Society

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One of the most exciting advances of the current generation of telescopes has been the detection of galaxies during the epoch of reionization, using deep fields that have pushed these instruments to their limits. It is essential to optimize our analyses of these fields in order to extract as much information as possible from them. In particular, standard methods of measuring the galaxy luminosity function discard information on large-scale dark matter density fluctuations, even though this large-scale structure drives galaxy formation and reionization during the Cosmic Dawn. Measuring these densities would provide a bedrock observable, connecting galaxy surveys to theoretical models of the reionization process and structure formation. Here, we use existing Hubble deep field data to simultaneously fit the universal luminosity function and measure large-scale densities for each Hubble deep field at z = 6–8 by directly incorporating priors on the large-scale density field and galaxy bias. Our fit of the universal luminosity function is consistent with previous methods but differs in the details. For the first time, we measure the underlying densities of the survey fields, including the most over/under-dense Hubble fields. We show that the distribution of densities is consistent with current predictions for cosmic variance. This analysis on just 17 fields is a small sample of what will be possible with the James Webb Space Telescope, which will measure hundreds of fields at comparable (or better) depths and at higher redshifts.

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Section: Fitting the Luminosity Functionmentioning

confidence: 99%

Section: Fieldmentioning

confidence: 99%

Section: Data Setsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A joint measurement of galaxy luminosity functions and large-scale field densities during the Epoch of Reionization

Trapp

Furlanetto

2022

Monthly Notices of the Royal Astronomical Society

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Balancing the efficiency and stochasticity of star formation with dust extinction in z ≳ 10 galaxies observed by JWST

Mirocha

Furlanetto

2022

Monthly Notices of the Royal Astronomical Society

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Early observations with JWST indicate an over-abundance of bright galaxies at redshifts z ≳ 10 relative to Hubble-calibrated model predictions. More puzzling still is the apparent lack of evolution in the abundance of such objects between z ∼ 9 and the highest redshifts yet probed, z ∼ 13–17. In this study, we first show that, despite a poor match with JWST LFs, semi-empirical models calibrated to UVLFs and colours at 4 ≲ z ≲ 8 are largely consistent with constraints on the properties of individual JWST galaxies, including their stellar masses, ages, and rest-ultraviolet spectral slopes. We then show that order-of-magnitude scatter in the star formation rate of galaxies (at fixed halo mass) can indeed boost the abundance of bright galaxies, provided that star formation is more efficient than expected in low-mass halos. However, this solution to the abundance problem introduces tension elsewhere: because it relies on the up-scattering of low-mass halos into bright magnitude bins, one expects typical ages, masses, and spectral slopes to be much lower than constraints from galaxies observed thus far. This tension can be alleviated by non-negligible reddening, suggesting that – if the first batch of photometrically-selected candidates are confirmed – star formation and dust production could be more efficient than expected in galaxies at z ≳ 10.

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First light and reionization epoch simulations (Flares) X: environmental galaxy bias and survey variance at high redshift

Thomas

Lovell

et al. 2023

Monthly Notices of the Royal Astronomical Society

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Upcoming deep galaxy surveys with JWST will probe galaxy evolution during the epoch of reionisation (EoR, 5 ≤ z ≤ 10) over relatively compact areas (e.g. ∼ 300 arcmin2 for the JADES GTO survey). It is therefore imperative that we understand the degree of survey variance, to evaluate how representative the galaxy populations in these studies will be. We use the First Light And Reionisation Epoch Simulations (Flares) to measure the galaxy bias of various tracers over an unprecedentedly large range in overdensity for a hydrodynamic simulation, and use these relations to assess the impact of bias and clustering on survey variance in the EoR. Star formation is highly biased relative to the underlying dark matter distribution, with the mean ratio of the stellar to dark matter density varying by a factor of 100 between regions of low and high matter overdensity (smoothed on a scale of 14 h−1cMpc). This is reflected in the galaxy distribution – the most massive galaxies are found solely in regions of high overdensity. As a consequence of the above, galaxies in the EoR are highly clustered, which can lead to large variance in survey number counts. For mean number counts N ≲ 100 (1000), in a unit redshift slice of angular area 300 arcmin2 (1.4 deg2), the 2-sigma range in N is roughly a factor of four (two). We present relations between the expected variance and survey area for different survey geometries; these relations will be of use to observers wishing to understand the impact of survey variance on their results.

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A framework for simultaneously measuring field densities and the high-z luminosity function

Cited by 5 publications

References 47 publications

A joint measurement of galaxy luminosity functions and large-scale field densities during the Epoch of Reionization

A joint measurement of galaxy luminosity functions and large-scale field densities during the Epoch of Reionization

Balancing the efficiency and stochasticity of star formation with dust extinction in z ≳ 10 galaxies observed by JWST

First light and reionization epoch simulations (Flares) X: environmental galaxy bias and survey variance at high redshift

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