分类： 天文学 >> 天文学 提交时间： 2023-02-19
Rachel Mandelbaum
Barnaby Rowe
James Bosch
Chihway Chang
Frederic Courbin
Mandeep Gill
Mike Jarvis
Arun Kannawadi
Tomasz Kacprzak
Claire Lackner
Alexie Leauthaud
Hironao Miyatake
Reiko Nakajima
Jason Rhodes
Melanie Simet
Joe Zuntz
Bob Armstrong
Sarah Bridle
Jean Coupon
Jörg P. Dietrich
摘要： The GRavitational lEnsing Accuracy Testing 3 (GREAT3) challenge is the third in a series of image analysis challenges, with a goal of testing and facilitating the development of methods for analyzing astronomical images that will be used to measure weak gravitational lensing. This measurement requires extremely precise estimation of very small galaxy shape distortions, in the presence of far larger intrinsic galaxy shapes and distortions due to the blurring kernel caused by the atmosphere, telescope optics, and instrumental effects. The GREAT3 challenge is posed to the astronomy, machine learning, and statistics communities, and includes tests of three specific effects that are of immediate relevance to upcoming weak lensing surveys, two of which have never been tested in a community challenge before. These effects include realistically complex galaxy models based on high-resolution imaging from space; spatially varying, physically-motivated blurring kernel; and combination of multiple different exposures. To facilitate entry by people new to the field, and for use as a diagnostic tool, the simulation software for the challenge is publicly available, though the exact parameters used for the challenge are blinded. Sample scripts to analyze the challenge data using existing methods will also be provided. See http://great3challenge.info and http://great3.projects.phys.ucl.ac.uk/leaderboard/ for more information.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Cheng Cheng
Jia-Sheng Huang
Christopher N. A. Willmer
Hong-Xin Zhang
Matthew L. N. Ashby
Hai Xu
Marcin Sawicki
Stephane Arnouts
Stephen Gwyn
Guillaume Desprez
Jean Coupon
Anneya Golob
Piaoran Liang
Tianwen Cao
Yaru Shi
Gaoxiang Jin
Chuan He
Shumei Wu
Zijian Li
Y. Sophia Dai
摘要： We present redshifts for 2753 low-redshift galaxies between $0.03 \lesssim z_{\rm spec}\lesssim0.5$ with 18 $\leq$ $r$ $\leq$ 22 obtained with Hectospec at the Multi-Mirror Telescope (MMT). The observations targeted the XMM-LSS, ELAIS-N1 and DEEP2-3 fields, each of which covers $\sim$ 1 deg$^2$. These fields are also part of the recently completed CFHT Large Area U-band Deep Survey (CLAUDS) and on-going Hyper Suprime-Cam deep fields surveys. The efficiency of our technique for selecting low-redshift galaxies is confirmed by the redshift distribution of our sources. In addition to redshifts, these high S/N spectra are used to measure ages, metallicities, and nuclear activity levels. In combination with the photometric catalogue in $u$, $g$, $r$, $i$, $z$, $y$ down to 27 AB mag, we are able to study the galaxy population down to stellar masses of $\sim$ 10$^8 M_\odot$ . This paper presents the observational strategy, the reduction procedure and properties of the galaxy sample.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Wei-Hao Wang
Sebastien Foucaud
Bau-Ching Hsieh
Hung-Yu Jian
Lihwai Lin
Yen-Ting Lin
Jean Coupon
Yasuhiro Hashimoto
Masami Ouchi
Kazuhiro Shimasaku
Youichi Ohyama
Keiichi Umetsu
Shiang-Yu Wang
Tzu-Ching Chang
摘要： The Subaru Hyper Suprime-Cam (HSC) Strategic Survey is the latest-generation
multi-band optical imaging survey for galaxy evolution and structure formation.
The "Ultra-Deep" component of the HSC survey provides $grizy$ broad-band images
over $\sim3.4$ deg$^2$ to detection limits of $\sim26$-28 AB, along with
narrow-band images, in the COSMOS and the SXDS fields. These images provide an
unprecedented combination of depths and area coverage, for the studies galaxies
up to $z\sim7$. However, the lack of coverage at $<4000$ Ang implies incomplete
sampling of the rest-frame UV at $z\lesssim 3$, which is critically needed for
understanding the buildup of stellar mass in the later cosmic time. We
conducted a multi-year CFHT $u^\ast$-band imaging campaign in the two HSC
Ultra-Deep fields with CFHT MegaCam. By including shallower archival data, we
reach 5-$\sigma$ depths of $u^\ast=28.1$ and 28.4 (AB) at the centers of the
COSMOS and SXDS fields, respectively, and $u^\ast=27.7$ and 27.8 in the central
1 deg$^2$ fields. The image quality is $\gtrsim0.90$ arcsec, fairly good for
the $u^\ast$ band. Both the photometric and astrometric quality of our data are
excellent. We show that the combination of our $u^\ast$-band and HSC data can
lead to high-quality photometric redshifts at $z=0$-3, and robust measurements
of rest-frame UV on galaxies at $0.4
点击量
待评议
点击量
下载量
评论
