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The upcoming galaxy large-scale surveys, such as the Vera C. Rubin Observatory's Legacy Survey of Space and Time (LSST), will generate photometry for billions of galaxies. The interpretation of large-scale weak lensing maps, as well as the…

Instrumentation and Methods for Astrophysics · Physics 2025-10-01 Alvaro Callejas-Tavera , Erik Molino-Minero-Re , Octavio Valenzuela

Accurate weak lensing mass estimates of clusters are needed in order to calibrate mass proxies for the cosmological exploitation of galaxy cluster surveys. Such measurements require accurate knowledge of the redshift distribution of the…

Astrophysics of Galaxies · Physics 2020-07-15 S. F. Raihan , T. Schrabback , H. Hildebrandt , D. Applegate , G. Mahler

Proposed cosmological surveys will make use of photometric redshifts of galaxies that are significantly fainter than any complete spectroscopic redshift surveys that exist to train the photo-z methods. We investigate the photo-z biases that…

Instrumentation and Methods for Astrophysics · Physics 2015-05-18 C. J. MacDonald , Gary Bernstein

We apply Bayesian statistics with prior probabilities of galaxy surface luminosity (SL) to improve photometric redshifts. We apply the method to a sample of 1266 galaxies with spectroscopic redshifts in the GOODS North and South fields at…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 Lifang Xia , Seth Cohen , Sangeeta Malhotra , James Rhoads , Norman Grogin , Nimish P. Hathi , Rogier A. Windhorst , Nor Pirzkal , Chun Xu

We release photometric redshifts, reaching $\sim$0.7, for $\sim$14M galaxies at $r\leq 20$ in the 11,500 deg$^2$ of the SDSS north and south galactic caps. These estimates were inferred from a convolution neural network (CNN) trained on…

Cosmology and Nongalactic Astrophysics · Physics 2023-10-16 M. Treyer , R. Ait-Ouahmed , J. Pasquet , S. Arnouts , E. Bertin , D. Fouchez

We introduce an ordinal classification algorithm for photometric redshift estimation, which significantly improves the reconstruction of photometric redshift probability density functions (PDFs) for individual galaxies and galaxy samples.…

Cosmology and Nongalactic Astrophysics · Physics 2015-07-20 Markus Michael Rau , Stella Seitz , Fabrice Brimioulle , Eibe Frank , Oliver Friedrich , Daniel Gruen , Ben Hoyle

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…

We present a multi-modal foundation model for astrophysical galaxy data, designed to map between simulation- and observation-based galactic features. Our encoder-only transformer flexibly ingests scalar quantities (e.g., redshifts, galaxy…

Astrophysics of Galaxies · Physics 2025-10-10 Bin Xia , Nesar Ramachandra , Azton I. Wells , Salman Habib , John Wise

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 the result of two binary classifier ensembled neural networks to identify catastrophic outliers for photo-z estimates within the COSMOS field utilizing only 8 and 5 photometric band passes, respectively. Our neural networks can…

Astrophysics of Galaxies · Physics 2025-03-31 Mitchell T. Dennis , Esther M. Hu , Lennox L. Cowie

We introduce Z-Sequence, a novel empirical model that utilises photometric measurements of observed galaxies within a specified search radius to estimate the photometric redshift of galaxy clusters. Z-Sequence itself is composed of a…

Astrophysics of Galaxies · Physics 2021-04-26 Matthew C. Chan , John P. Stott

Accurate photometric redshift (photo-$z$) estimation requires support from multi-band observational data. However, in the actual process of astronomical observations and data processing, some sources may have missing observational data in…

Instrumentation and Methods for Astrophysics · Physics 2024-06-05 Zhijian Luo , Zhirui Tang , Zhu Chen , Liping Fu , Wei Du , Shaohua Zhang , Yan Gong , Chenggang Shu , Junhao Lu , Yicheng Li , Xian-Min Meng , Xingchen Zhou , Zuhui Fan

The availability of large, public, multi-modal astronomical datasets presents an opportunity to execute novel research that straddles the line between science of AI and science of astronomy. Photometric redshift estimation is a…

Instrumentation and Methods for Astrophysics · Physics 2024-02-07 Andrew Engel , Gautham Narayan , Nell Byler

We investigate the impact of photometric signal-to-noise (S/N) on the precision of photometric redshifts in multi-band imaging surveys, using both simulations and real data. We simulate the optical 4-band (BVRz) Deep Lens Survey (DLS,…

Astrophysics · Physics 2009-11-13 V. E. Margoniner , D. M. Wittman

Imaging billions of galaxies every few nights during ten years, LSST should be a major contributor to precision cosmology in the 2020 decade. High precision photometric data will be available in six bands, from near-infrared to…

We present a convolutional neural network to classify distinct cosmological scenarios based on the statistically similar weak-lensing maps they generate. Modified gravity (MG) models that include massive neutrinos can mimic the standard…

Cosmology and Nongalactic Astrophysics · Physics 2019-07-17 Austin Peel , Florian Lalande , Jean-Luc Starck , Valeria Pettorino , Julian Merten , Carlo Giocoli , Massimo Meneghetti , Marco Baldi

In astronomy, neural networks are often trained on simulation data with the prospect of being used on telescope observations. Unfortunately, training a model on simulation data and then applying it to instrument data leads to a substantial…

Instrumentation and Methods for Astrophysics · Physics 2021-07-16 A. Ćiprijanović , D. Kafkes , K. Downey , S. Jenkins , G. N. Perdue , S. Madireddy , T. Johnston , G. F. Snyder , B. Nord

Photometric redshifts play an important role as a measure of distance for various cosmological topics. Spectroscopic redshifts are only available for a very limited number of objects but can be used for creating statistical models. A broad…

Instrumentation and Methods for Astrophysics · Physics 2016-08-30 Kai Lars Polsterer , Antonio D'Isanto , Fabian Gieseke

We describe a new method of combining optical and infrared photometry to select Luminous Red Galaxies (LRGs) at redshifts $z > 0.6$. We explore this technique using a combination of optical photometry from CFHTLS and HST, infrared…

Astrophysics of Galaxies · Physics 2015-04-27 Abhishek Prakash , Timothy C. Licquia , Jeffrey A. Newman , Sandhya M. Rao

Galaxy cross-correlations with high-fidelity redshift samples hold the potential to precisely calibrate systematic photometric redshift uncertainties arising from the unavailability of complete and representative training and validation…

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