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In the next decade, the LSST will become a major facility for the astronomical community. However accurately determining the redshifts of the observed galaxies without using spectroscopy is a major challenge. Reconstruction of the redshifts…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-12 Alexia Gorecki , Alexandra Abate , Réza Ansari , Aurélien Barrau , Sylvain Baumont , Marc Moniez , Jean-Stéphane Ricol

Few galaxies have been found between the redshift ranges z < ~1 probed by magnitude-limited surveys and z > ~3 probed by Lyman-break surveys. Comparison of galaxy samples at lower and higher redshift suggests that large numbers of stars…

We present a machine-learning photometric redshift analysis of the Kilo-Degree Survey Data Release 3, using two neural-network based techniques: ANNz2 and MLPQNA. Despite limited coverage of spectroscopic training sets, these ML codes…

In this paper we present photometric redshifts for 2.7 million galaxies in the XMM-LSS and COSMOS fields, both with rich optical and near-infrared data from VISTA and HyperSuprimeCam. Both template fitting (using galaxy and Active Galactic…

Astrophysics of Galaxies · Physics 2022-06-03 P. W. Hatfield , M. J. Jarvis , N. Adams , R. A. A. Bowler , B. Häußler , K. J. Duncan

We discuss a method aiming to use photometric redshifts in lensing clusters to access the population of distant background sources. The amplification provided by gravitational lensing allows to calibrate photometric redshifts 1 to 3…

Astrophysics · Physics 2007-05-23 Roser Pello , Jean-Paul Kneib , Micol Bolzonella , Joan-Marc Miralles

We show how to enhance the redshift accuracy of surveys consisting of tracers with highly uncertain positions along the line of sight. Photometric surveys with redshift uncertainty delta_z ~ 0.03 can yield final redshift uncertainties of…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 Jens Jasche , Benjamin D. Wandelt

RedGOLD searches for red-sequence galaxy overdensities while minimizing contamination from dusty star-forming galaxies. It imposes an NFW profile and calculates cluster detection significance and richness. We optimize these latter two…

Cosmology and Nongalactic Astrophysics · Physics 2017-05-15 Rossella Licitra , Simona Mei , Anand Raichoor , Thomas Erben , Hendrik Hildebrandt

Recent large-scale galaxy spectroscopic surveys, such as the Sloan Digital Sky Survey (SDSS), enable us to execute a systematic, relatively-unbiased search for galaxy clusters. Such surveys make it possible to measure the 3-d distribution…

Astrophysics · Physics 2009-11-13 Joo H. Yoon , Kevin Schawinski , Yun-Kyeong Sheen , Chang H. Ree , Sukyoung K. Yi

We present a modified version of the friends-of-friends (FOF) structure finding algorithm, designed specifically to locate groups or clusters of galaxies in photometric redshift datasets. The main objective of this paper is to show that…

Astrophysics · Physics 2009-11-10 C. S. Botzler , J. Snigula , R. Bender , U. Hopp

We present a novel method to estimate accurate redshifts of star-forming galaxies by measuring the flux ratio of the same emission line observed through two adjacent narrow-band filters. We apply this method to our NB912 and new NB921 data…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-18 Masao Hayashi , Tadayuki Kodama , Yusei Koyama , Ken-ichi Tadaki , Ichi Tanaka , Rhythm Shimakawa , Yuichi Matsuda , David Sobral , Philip N. Best , Ian Smail

In an investigation of the cause of the cosmic microwave background decrement in the field of the z = 3.8 quasar pair PC1643+4631, we have carried out a study to photometrically estimate the redshifts of galaxies in deep multi-colour…

Astrophysics · Physics 2009-10-31 Garret Cotter , Toby Haynes , Joanne C. Baker , Michael E. Jones , Richard Saunders

AIMS: We present a weak lensing search of galaxy clusters in the 4 deg2 of the CFHT Legacy Survey Deep. This work aims at building a mass-selected sample of clusters. METHODS: We use the deep i' band images to perform weak lensing mass…

Astrophysics · Physics 2009-11-11 Raphael Gavazzi , Genevieve Soucail

We present the development of a photometrically selected massive galaxy catalog, targeting Luminous Red Galaxies (LRGs) and massive blue galaxies at redshifts $z\geq 0.55$. Massive galaxy candidates are selected using infrared/optical…

Astrophysics of Galaxies · Physics 2017-01-18 Carolina Núñez , David N. Spergel , Shirley Ho

We first present a catalogue of photometric redshifts for 14.68 million galaxies derived from the 7-band photometric data of Hyper Suprime-Cam Subaru Strategic Program and the Wide-field Infrared Survey Explorer using the nearest-neighbour…

Cosmology and Nongalactic Astrophysics · Physics 2020-11-20 Z. L. Wen , J. L. Han

We report the first results from the Z-FOURGE survey: the discovery of a candidate galaxy cluster at z = 2.2 consisting of two compact overdensities with red galaxies detected at >20{\sigma} above the mean surface density. The discovery was…

Galaxy groups and clusters are formidable cosmological probes. They permit the studying of the environmental effects on galaxy formation. A reliable detection of galaxy groups is an open problem and is important for ongoing and future…

Cosmology and Nongalactic Astrophysics · Physics 2018-10-17 Elmo Tempel , Maarja Kruuse , Rain Kipper , Taavi Tuvikene , Jenny G. Sorce , Radu S. Stoica

We present a catalogue of 4499 groups and clusters of galaxies from the first data release of the multi-filter (5 broad, 7 narrow) Southern Photometric Local Universe Survey (S-PLUS). These groups and clusters are distributed over 273…

Galaxy clusters can be detected as surface brightness enhancements in smoothed optical surveys. This method does not require individual galaxies to be identifiable, and enables clusters to be detected out to surprisingly high redshifts, as…

Astrophysics · Physics 2009-11-07 Matthias Bartelmann , Simon D. M. White