The redshift distribution of cosmological samples: a forward modeling approach

Herbel, Jörg; Kacprzak, T.; Amara, Adam; Réfrégier, Alexandre; Bruderer, C.; Nicola, Andrina

doi:10.1088/1475-7516/2017/08/035

Cited by 30 publications

(139 citation statements)

References 55 publications

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“…The forward modeling approach is becoming a widely used technique [1,28,29], and consists of generating observable quantities from an astrophysical model containing, for instance, the evolution of the luminosity functions of red and blue galaxies with cosmic time (see e.g. [1]). A similar approach has also been performed recently for image simulations with narrow-band photometric data from the Physics of the Accelerating Universe Survey, (PAUS 8 ), as shown in [30].…”

Section: Contentsmentioning

confidence: 99%

“…To simulate galaxy spectra, we need basic galaxy properties as inputs. The model from which such properties are drawn is fully described in [1], and further clarified in [30]. In this section, we review the aspects of the model necessary for simulating galaxy spectra given an input galaxy population.…”

Section: Galaxy Population Modelmentioning

confidence: 99%

“…In this section, we review the aspects of the model necessary for simulating galaxy spectra given an input galaxy population. For a more complete description of the model we refer the reader to [1].…”

Section: Galaxy Population Modelmentioning

confidence: 99%

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Forward modeling of spectroscopic galaxy surveys: application to SDSS

Fagioli

Riebartsch

Nicola

et al. 2018

J. Cosmol. Astropart. Phys.

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Galaxy spectra are essential to probe the spatial distribution of galaxies in our Universe. To better interpret current and future spectroscopic galaxy redshift surveys, it is important to be able to simulate these data sets. We describe Uspec, a forward modeling tool to generate galaxy spectra taking into account some intrinsic galaxy properties as well as instrumental responses of a given telescope. The model for the intrinsic properties of the galaxy population, i.e., the luminosity functions, and size and spectral coefficients distributions, was developed in an earlier work for broad-band imaging surveys [1], and we now aim to test the model further using spectroscopic data. We apply Uspec to the SDSS/CMASS sample of Luminous Red Galaxies (LRGs). We construct selection cuts that match those used to build this LRG sample, which we then apply to data and simulations in the same way. The resulting real and simulated average spectra show a good statistical agreement overall, with residual differences likely coming from a bluer galaxy population of the simulated sample. We also do not explore the impact of non-solar element ratios in our simulations. For a quantitative comparison, we perform Principal Component Analysis (PCA) of the sets of spectra. By comparing the PCs constructed from simulations and data, we find good agreement for all components. The distributions of the eigencoefficients also show an appreciable overlap. We are therefore able to properly simulate the LRG sample taking into account the SDSS/BOSS instrumental responses. The differences between the two samples can be ascribed to the intrinsic properties of the simulated galaxy population, which can be reduced by further improvements of our modelling method in the future. We discuss how these results can be useful for the forward modeling of upcoming large spectroscopic surveys.

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Section: Contentsmentioning

confidence: 99%

Section: Galaxy Population Modelmentioning

confidence: 99%

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Forward modeling of spectroscopic galaxy surveys: application to SDSS

Fagioli

Riebartsch

Nicola

et al. 2018

J. Cosmol. Astropart. Phys.

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“…The models are based on underlying distributions that need to be calibrated using existing data. In this work, we test the model described in [3] by using the extensive photometry provided by the PAUS survey.…”

Section: Discussionmentioning

confidence: 99%

“…In this section, we describe the method (hereafter, pipeline) that we use to analyze and apply the forward modeling approach to PAUS images and test the model described in [3]. We apply the pipeline to the PAUS images belonging to the COSMOS field.…”

Section: Methodsmentioning

confidence: 99%

The PAU Survey: a forward modeling approach for narrow-band imaging

Tortorelli

Bruna

Herbel

et al. 2018

J. Cosmol. Astropart. Phys.

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Weak gravitational lensing is a powerful probe of the dark sector, once measurement systematic errors can be controlled. In [1], a calibration method based on forward modeling, called MCCL, was proposed. This relies on fast image simulations (e.g., UFig) [2] that capture the key features of galaxy populations and measurement effects. The MCCL approach has been used in [3] to determine the redshift distribution of cosmological galaxy samples and, in the process, the authors derived a model for the galaxy population mainly based on broad-band photometry. Here, we test this model by forward modeling the 40 narrow-band photometry given by the novel PAU Survey (PAUS). For this purpose, we apply the same forced photometric pipeline on data and simulations using Source Extractor [4]. The image simulation scheme performance is assessed at the image and at the catalogues level. We find good agreement for the distribution of pixel values, the magnitudes, in the magnitude-size relation and the interband correlations. A principal component analysis is then performed, in order to derive a global comparison of the narrow-band photometry between the data and the simulations. We use a 'mixing' matrix to quantify the agreement between the observed and simulated sets of Principal Components (PCs). We find good agreement, especially for the first three most significant PCs. We also compare the coefficients of the PCs decomposition. While there are slight differences for some coefficients, we find that the distributions are in good agreement. Together, our results show that the galaxy population model derived from broad-band photometry is in good overall agreement with the PAUS data. This offers good prospect for incorporating spectral information to the galaxy model by adjusting it to the PAUS narrow-band data using forward modeling.

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Distributions of pseudo-redshifts and durations (observed and intrinsic) of Fermi GRBs

Zitouni

Guessoum

Alqassimi

et al. 2018

Astrophys Space Sci

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Ever since the insightful analysis of the durations of gamma-ray bursts (GRBs) by Kouveliotou et al. (1993), GRBs have most often been classified into two populations: "short bursts" (shorter than 2.0 seconds) and "long bursts" (longer than 2.0 seconds). However, recent works have suggested the existence of an intermediate population in the bursts observed by the Swift satellite. Moreover, some researchers have questioned the universality of the 2.0-second dividing line between short and long bursts: some bursts may be short but actually result from collapsars, the physical mechanism behind normally long bursts, and some long ones may originate from mergers, the usual progenitors of short GRBs.In this work, we focus on GRBs detected by the Fermi satellite (which has a much higher detection rate than Swift and other burst-detecting satellites) and study the distribution of their durations measured in the observer's reference frame and, for those with known redshifts, in the bursts' reference frames. However, there are relatively few bursts with measured redshifts, and this makes an accurate study difficult. To overcome this problem, we follow Zhang and Wang (2018) and determine a "pseudo-redshift" from the correlation relation between the luminosity L p and the energy E p , both of which are calculated at the peak of the flux. Interestingly, we find that the uncertainties in the quantities observed and used in the determination of pseudo-redshifts, do affect the precision of the individual results significantly, but they keep the distribution of pseudo-redshifts very similar to that of the actual ones and thus allow us to use pseudo-redshifts for our statistical study. We briefly present the advantages and disadvantages of using pseudo-redshifts in this context.We use the reduced chi-square and the maximization of the log-likelihood to statistically analyze the distribution of Fermi GRB durations. Both methods show that the distribution of the observed (measured) and the intrinsic (source/rest frame) bursts durations are better represented by two groups/populations, rather than three.

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The redshift distribution of cosmological samples: a forward modeling approach

Cited by 30 publications

References 55 publications

Forward modeling of spectroscopic galaxy surveys: application to SDSS

Forward modeling of spectroscopic galaxy surveys: application to SDSS

The PAU Survey: a forward modeling approach for narrow-band imaging

Distributions of pseudo-redshifts and durations (observed and intrinsic) of Fermi GRBs

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