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The identifications of quasars in the redshift range 2.2<z<3 are known to be very inefficient as their optical colors are indistinguishable from those of stars. Recent studies have proposed to use optical variability or near-IR colors to…

宇宙学与河外天体物理 · 物理学 2015-05-28 Xue-Bing Wu , Ran Wang , Kasper B. Schmidt , Fuyan Bian , Linhua Jiang , Xiaohui Fan

In this work, we want to exploit the magnification bias of the SMGs using two different foreground samples, quasi-stellar objects (QSOs) and galaxies. Our aim is to study and compare their mass density profiles and estimate their masses and…

星系天体物理 · 物理学 2022-11-30 D. Crespo , J. González-Nuevo , L. Bonavera , M. M. Cueli , J. M. Casas , E. Goitia

We cross-match the two currently largest all-sky photometric catalogs, mid-infrared WISE and SuperCOSMOS scans of UKST/POSS-II photographic plates, to obtain a new galaxy sample that covers 3pi steradians. In order to characterize and…

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.…

The automatic classification of X-ray detections is a necessary step in extracting astrophysical information from compiled catalogs of astrophysical sources. Classification is useful for the study of individual objects, statistics for…

天体物理仪器与方法 · 物理学 2024-01-30 Víctor Samuel Pérez-Díaz , Juan Rafael Martínez-Galarza , Alexander Caicedo , Raffaele D'Abrusco

We present a machine learning search for local, low-mass galaxies ($z < 0.02$ and $10^6 M_\odot < M_* < 10^9 M_\odot$) using the combined photometric data from the DESI Imaging Legacy Surveys and the WISE survey. We introduce the spectrally…

星系天体物理 · 物理学 2025-03-19 Huanian Zhang , Guangping Ye , Rongyu Wu , Dennis Zaritsky

The use of photometric redshifts in cosmology is increasing. Often, however these photo-zs are treated like spectroscopic observations, in that the peak of the photometric redshift, rather than the full probability density function (PDF),…

宇宙学与河外天体物理 · 物理学 2015-05-13 Adam D Myers , Martin White , Nicholas M. Ball

Discovering pulsars is a significant and meaningful research topic in the field of radio astronomy. With the advent of astronomical instruments such as he Five-hundred-meter Aperture Spherical Telescope (FAST) in China, data volumes and…

天体物理仪器与方法 · 物理学 2019-10-24 Ping Guo , Fuqing Duan , Pei Wang , Yao Yao , Qian Yin , Xin Xin

Quasars experiencing strong lensing offer unique viewpoints on subjects related to the cosmic expansion rate, the dark matter profile within the foreground deflectors, and the quasar host galaxies. Unfortunately, identifying them in…

A dataset is a shred of crucial evidence to describe a task. However, each data point in the dataset does not have the same potential, as some of the data points can be more representative or informative than others. This unequal importance…

机器学习 · 计算机科学 2022-03-21 Jaehong Yoon , Divyam Madaan , Eunho Yang , Sung Ju Hwang

We report on newly identified galaxy clusters from the high signal-to-noise ($>5$-$\sigma$) end of the second all-sky \textit{Planck} Sunyaev-Zel'dovich (SZ) catalog (PSZ2). The clusters are identified in deep, optical imaging from the Kitt…

宇宙学与河外天体物理 · 物理学 2018-11-28 Steven Boada , John P. Hughes , Felipe Menanteau , Peter Doze , L. Felipe Barrientos , L. Infante

The morphologies of astronomical sources are highly complex, making it essential not only to classify the identified sources into their predefined categories but also to determine the sources that are most similar to a given query source.…

图像与视频处理 · 电气工程与系统科学 2024-10-14 Steven Ndungu , Trienko Grobler , Stefan J. Wijnholds , George Azzopardi

We present a new measurement of the space density of high redshift (3.0<z<4.5), X-ray selected QSOs obtained by exploiting the deep and uniform multiwavelength coverage of the COSMOS survey. We have assembled a statistically large (40…

The number density and correlation function of galaxies are two key quantities to characterize the distribution of the observed galaxy population. High-$z$ spectroscopic surveys, which usually involve complex target selection and are…

星系天体物理 · 物理学 2024-02-05 Jiacheng Meng , Cheng Li , Houjun Mo , Yangyao Chen , Kai Wang

Cosmological constraints from galaxy clusters rely on accurate measurements of the mass and internal structure of clusters. An important source of systematic uncertainty in cluster mass and structure measurements is the secure selection of…

星系天体物理 · 物理学 2016-10-12 Felicia Ziparo , Graham P. Smith , Nobuhiro Okabe , Chris P. Haines , Maria J. Pereira , Eiichi Egami

We obtained deep 8.5'x8.5' near-infrared images within four high-redshift survey fields, measured the Ks magnitudes of 300 optically selected galaxies with spectroscopic redshift 1.8<z<2.6, and compared the spatial clustering strength of…

Slitless spectroscopy is a traditional method for selecting quasars. In this paper, we develop a procedure for selecting quasars (QSOs) using the 3D-HST G141 slitless spectra. We initially identify over 6,000 sources with emission lines…

星系天体物理 · 物理学 2025-05-21 Yuxuan Pang , Xue-Bing Wu , Yuming Fu , Rui Zhu , Tao Ji , Qinchun Ma , Xiaotong Feng

In a previous paper we presented the results of applying machine learning to classify whether an HI 21-cm absorption spectrum arises in a source intervening the sight-line to a more distant radio source or within the host of the radio…

天体物理仪器与方法 · 物理学 2021-07-14 S. J. Curran

Precision photometric redshifts will be essential for extracting cosmological parameters from the next generation of wide-area imaging surveys. In this paper we introduce a photometric redshift algorithm, ArborZ, based on the…

宇宙学与河外天体物理 · 物理学 2010-05-06 David W. Gerdes , Adam J. Sypniewski , Timothy A. McKay , Jiangang Hao , Matthew R. Weis , Risa H. Wechsler , Michael T. Busha

We demonstrate the use of the AKARI survey photometric data in the study of galactic star formation. Our aim was to select young stellar objects (YSOs) in the AKARI FIS catalogue. We used AKARI Far-Infrared Surveyor and Wide-field Infrared…

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