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We present a galaxy catalog simulator which turns N-body simulations with subhalos into multiband photometric mocks. The simulator assigns galaxy properties to each subhalo to reproduce the observed cluster galaxy halo occupation…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-27 Jeeseon Song , Joseph J. Mohr , Wayne A. Barkhouse , Michael S. Warren , Cody Rude

We explore the enhanced self-calibration of photometric galaxy redshift distributions, $n(z)$, through the combination of up to six two-point functions. Our $\rm 3\times2pt$ configuration is comprised of photometric shear, spectroscopic…

Given multiband photometric data from the SDSS DR6, we estimate galaxy redshifts. We employ a Random Forest trained on color features and spectroscopic redshifts from 80,000 randomly chosen primary galaxies yielding a mapping from color to…

This white paper summarizes the conclusions of the Snowmass White Paper "Spectroscopic Needs for Imaging Dark Energy Experiments" (arXiv:1309.5384) which are relevant to the calibration of LSST photometric redshifts; i.e., the accurate…

Instrumentation and Methods for Astrophysics · Physics 2014-10-17 Samuel J. Schmidt , Jeffrey A. Newman , Alexandra Abate , the Spectroscopic Needs White Paper Team

Determining the radial positions of galaxies up to a high accuracy depends on the correct identification of salient features in their spectra. Classical techniques for spectroscopic redshift estimation make use of template matching with…

Instrumentation and Methods for Astrophysics · Physics 2019-05-15 Joana Frontera-Pons , Florent Sureau , Bruno Moraes , Jérôme Bobin , Filipe Abdalla

Galaxy color gradients - i.e., spectral energy distributions that vary across the galaxy profile - will impact galaxy shape measurements when the modeled point spread function (PSF) corresponds to that for a galaxy with spatially uniform…

Cosmology and Nongalactic Astrophysics · Physics 2019-07-11 Sowmya Kamath , Joshua E. Meyers , Patricia R. Burchat

We present a method to refine photometric redshift galaxy catalogs by comparing their color-space matching with overlapping spectroscopic calibration data. We focus on cases where photometric redshifts (photo-$z$) are estimated empirically.…

We identify and study a previously unknown systematic effect on cosmic shear measurements, caused by the selection of galaxies used for shape measurement, in particular the rejection of close (blended) galaxy pairs. We use ray-tracing…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 Jan Hartlap , Stefan Hilbert , Peter Schneider , Hendrik Hildebrandt

We develop a general method to "self-calibrate" observations of galaxy clustering with respect to systematics associated with photometric calibration errors. We first point out the danger posed by the multiplicative effect of calibration…

Cosmology and Nongalactic Astrophysics · Physics 2015-02-24 Daniel L. Shafer , Dragan Huterer

We present improved methods for using stars found in astronomical exposures to calibrate both star and galaxy colors as well as to adjust the instrument flat field. By developing a spectroscopic model for the SDSS stellar locus in…

We explore the effects of incorporating redshift uncertainty into measurements of galaxy clustering and cross-correlations of galaxy positions and cosmic microwave background (CMB) lensing maps. We use a simple Gaussian model for a redshift…

Cosmology and Nongalactic Astrophysics · Physics 2020-03-26 Ross Cawthon

As a means of better understanding the evolution of optically selected galaxies we consider the distribution of galaxies within the multicolor space $U$, $B_J$, $R_F$ and $I_N$. We find that they form an almost planar distribution out to…

Astrophysics · Physics 2008-11-26 A. J. Connolly , I. Csabai , A. S. Szalay , D. C. Koo , R. G. Kron , J. A. Munn

Filament finders are limited, among other things, by the abundance of spectroscopic redshift data. As there are proportionally more photometric redshift data than spectroscopic, we aim to use photometric data to improve and expand the areas…

Cosmology and Nongalactic Astrophysics · Physics 2023-02-15 Moorits Mihkel Muru , Elmo Tempel

We present a photometric method for identifying stars, galaxies and quasars in multi-color surveys, which uses a library of >65000 color templates. The method aims for extracting the information content of object colors in a statistically…

Astrophysics · Physics 2009-06-16 C. Wolf , K. Meisenheimer , H. -J. Röser

Photometric redshift estimation is becoming an increasingly important technique, although the currently existing methods present several shortcomings which hinder their application. Here it is shown that most of those drawbacks are…

Astrophysics · Physics 2011-05-05 Narciso Benitez

Although photometric redshifts (photo-z's) are crucial ingredients for current and upcoming large-scale surveys, the high-quality spectroscopic redshifts currently available to train, validate, and test them are substantially…

We compare three methods to measure the count-in-cell probability density function of galaxies in a spectroscopic redshift survey. From this comparison we found that when the sampling is low (the average number of object per cell is around…

We determine the accuracy of galaxy redshift distributions as estimated from photometric redshift probability distributions $p(z)$. Our method utilises measurements of the angular cross-correlation between photometric galaxies and an…

We present a simple method for evaluating the nonlinear biasing function of galaxies from a redshift survey. The nonlinear biasing is characterized by the conditional mean of the galaxy density fluctuation given the underlying mass density…

Astrophysics · Physics 2009-10-31 Yair Sigad , Enzo Branchini , Avishai Dekel

We forecast the ability of bispectrum estimators to constrain primordial non-Gaussianity using future photometric galaxy redshift surveys. A full-sky survey with photometric redshift resolution of $\sigma_z/(1+z)=0.05$ in the redshift range…

Cosmology and Nongalactic Astrophysics · Physics 2023-08-09 Julius Wons , Emanuela Dimastrogiovanni , Matteo Fasiello , Jan Hamann , Matthew C. Johnson
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