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Forthcoming astronomical surveys are expected to detect new sources in such large numbers that measuring their spectroscopic redshift measurements will be not be practical. Thus, there is much interest in using machine learning to yield the…

Cosmology and Nongalactic Astrophysics · Physics 2022-03-14 S. J. Curran

We present a catalog of 1,172,157 quasar candidates selected from the photometric imaging data of the Sloan Digital Sky Survey (SDSS). The objects are all point sources to a limiting magnitude of i=21.3 from 8417 sq. deg. of imaging from…

(abridged) Mass loss is a key parameter in the evolution of massive stars, with discrepancies between theory and observations and with unknown importance of the episodic mass loss. To address this we need increased numbers of classified…

Solar and Stellar Astrophysics · Physics 2022-10-19 Grigoris Maravelias , Alceste Z. Bonanos , Frank Tramper , Stephan de Wit , Ming Yang , Paolo Bonfini

The Planck list of high-redshift source candidates (the PHz catalogue) contains 2151 peaks in the cosmic infrared background, unresolved by Planck's 5 arcmin beam. Follow-up spectroscopic observations have revealed that some of these…

Astrophysics of Galaxies · Physics 2022-06-22 Caleb Lammers , Ryley Hill , Seunghwan Lim , Douglas Scott , Raoul Cañameras , Hervé Dole

We present a method of selecting quasars up to redshift $\approx$ 6 with random forests, a supervised machine learning method, applied to Pan-STARRS1 and WISE data. We find that, thanks to the increasing set of known quasars we can assemble…

Cross-correlations between the galaxy number density in a lensing source sample and that in an overlapping spectroscopic sample can in principle be used to calibrate the lensing source redshift distribution. In this paper, we study in…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-16 Roland de Putter , Olivier Doré , Sudeep Das

Photometric redshifts are necessary for enabling large-scale multicolour galaxy surveys to interpret their data and constrain cosmological parameters. While the increased depth of future surveys such as the Large Synoptic Survey Telescope…

Cosmology and Nongalactic Astrophysics · Physics 2018-12-03 Daniel M. Jones , Alan F. Heavens

A thorough study of QSO-galaxy correlations has been done on a region close to the North Galactic Pole using a complete subsample of the optically selected CFHT/MMT QSO survey and the galaxy catalog of Odewahn and Aldering (1995). Although…

Astrophysics · Physics 2009-10-30 I. Ferreras , N. Benitez , E. Martinez-Gonzalez

Quasi-stellar objects (QSOs) are a basis for an absolute reference system for astrometric studies. There is a need for creating such system behind nearby galaxies, to facilitate the measuring of the proper motions of these galaxies.…

As performance of dedicated facilities continually improved, massive pulsar candidates are being received, which makes selecting valuable pulsar signals from candidates challenging. In this paper, we designed a deep convolutional neural…

Instrumentation and Methods for Astrophysics · Physics 2019-09-25 Yuanchao Wang , Mingtao Li , Zhichen Pan , Jianhua Zheng

As spectroscopic surveys continue to grow in size, the problem of classifying spectra targeted as quasars (QSOs) will need to move beyond its historical reliance on human experts. Instead, automatic classifiers will increasingly become the…

Cosmology and Nongalactic Astrophysics · Physics 2020-12-09 James Farr , Andreu Font-Ribera , Andrew Pontzen

We use the mock catalog of galaxies, constructed based on the COSMOS galaxy catalog including information on photometric redshifts (photo-z) and SED types of galaxies, in order to study how to define a galaxy subsample suitable for weak…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 Atsushi J. Nishizawa , Masahiro Takada , Takashi Hamana , Hisanori Furusawa

Mass loss is a key aspect of stellar evolution, particularly in evolved massive stars, yet episodic mass loss remains poorly understood. To investigate this, we need evolved massive stellar populations across various galactic environments.…

We present photometric selection of type 1 quasars in the $\approx5.3~{\rm deg}^{2}$ XMM-Large Scale Structure (XMM-LSS) survey field with machine learning. We constructed our training and \hbox{blind-test} samples using spectroscopically…

Astrophysics of Galaxies · Physics 2024-12-11 Jian Huang , Bin Luo , W. N. Brandt , Ying Chen , Qingling Ni , Yongquan Xue , Zijian Zhang

We present a catalog of unobscured QSO candidates in the southern hemisphere from the early interim data of the KMTNet Synoptic Survey of Southern Sky (KS4). The KS4 data covers $\sim2500\,{\rm deg}^{2}$ sky area, reaching 5$\sigma$…

We search for high redshift ($z\sim$1-2) galaxy clusters using low luminosity radio galaxies (FR~I) as beacons and our newly developed Poisson Probability Method (PPM) based on photometric redshift information and galaxy number counts. We…

Astrophysics of Galaxies · Physics 2015-06-22 Gianluca Castignani , Marco Chiaberge , Annalisa Celotti , Colin Norman , Gianfranco De Zotti

Despite the great promise of machine-learning algorithms to classify and predict astrophysical parameters for the vast numbers of astrophysical sources and transients observed in large-scale surveys, the peculiarities of the training data…

Instrumentation and Methods for Astrophysics · Physics 2015-05-28 Joseph W. Richards , Dan L. Starr , Henrik Brink , Adam A. Miller , Joshua S. Bloom , Nathaniel R. Butler , J. Berian James , James P. Long , John Rice

We introduce a probabilistic approach to select 6<z<8 quasar candidates for spectroscopic follow-up, which is based on density estimation in the high-dimensional space inhabited by the optical and near-infrared photometry. Density…

Astrophysics of Galaxies · Physics 2022-08-03 Riccardo Nanni , Joseph F. Hennawi , Feige Wang , Jinyi Yang , Jan-Torge Schindler , Xiaohui Fan

Identifying galaxy groups from redshift surveys of galaxies plays an important role in connecting galaxies with the underlying dark matter distribution. Current and future high-$z$ spectroscopic surveys, usually incomplete in redshift…

Astrophysics of Galaxies · Physics 2020-10-14 Kai Wang , H. J. Mo , Cheng Li , Jiacheng Meng , Yangyao Chen

High-redshift quasars are important tracers of structure and evolution in the early universe. However, they are very rare and difficult to find when using color selection because of contamination from late-type dwarfs. High-redshift quasar…