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We used 3.1 million spectroscopically labelled sources from the Sloan Digital Sky Survey (SDSS) to train an optimised random forest classifier using photometry from the SDSS and the Widefield Infrared Survey Explorer (WISE). We applied this…

Astrophysics of Galaxies · Physics 2020-07-15 A. O. Clarke , A. M. M. Scaife , R. Greenhalgh , V. Griguta

Lensed quasars are key to many areas of study in astronomy, offering a unique probe into the intermediate and far universe. However, finding lensed quasars has proved difficult despite significant efforts from large collaborations. These…

We present SQUEzE, a software package to classify quasar spectra and estimate their redshifts. SQUEzE is a random forest classifier operating on the parameters of candidate emission peaks identified in the spectra. We test the performance…

Astrophysics of Galaxies · Physics 2020-07-01 Ignasi Pérez-Ràfols , Matthew M. Pieri , Michael Blomqvist , Sean Morrison , Debopam Som

Future radio surveys will generate catalogues of tens of millions of radio sources, for which redshift estimates will be essential to achieve many of the science goals. However, spectroscopic data will be available for only a small fraction…

Instrumentation and Methods for Astrophysics · Physics 2019-09-11 Ray P. Norris , M. Salvato , G. Longo , M. Brescia , T. Budavari , S. Carliles , S. Cavuoti , D. Farrah , J. Geach , K. Luken , A. Musaeva , K. Polsterer , G. Riccio , N. Seymour , V. Smolčić , M. Vaccari , P. Zinn

We consider the statistical problem of catalogue matching from a machine learning perspective with the goal of producing probabilistic outputs, and using all available information. A framework is provided that unifies two existing…

Astrophysics · Physics 2009-11-11 D. J. Rohde , M. R. Gallagher , M. J. Drinkwater , K. A. Pimbblet

The Gaia DR3 has provided a large sample of more than 6.6 million quasar candidates with high completeness but low purity. Previous work on the CatNorth quasar candidate catalog has shown that including external multiband data and applying…

Discrepancies between cosmological parameter estimates from cosmic shear surveys and from recent Planck cosmic microwave background measurements challenge the ability of the highly successful $\Lambda$CDM model to describe the nature of the…

Cosmology and Nongalactic Astrophysics · Physics 2025-05-06 Maximilian Autenrieth , Angus H. Wright , Roberto Trotta , David A. van Dyk , David C. Stenning , Benjamin Joachimi

We assemble the largest CIV absorption line catalogue to date, leveraging machine learning, specifically Gaussian processes, to remove the need for visual inspection for detecting CIV absorbers. The catalogue contains probabilities…

Astrophysics of Galaxies · Physics 2023-09-26 Reza Monadi , Ming-Feng Ho , Kathy L. Cooksey , Simeon Bird

Photometric redshifts (photo-$z$s) are an essential tool for galaxy evolution science with JWST. However, for deep surveys with more limited filter sets (i.e. $N_{\text{filt}} \sim6$) such as large pure parallel surveys, the most commonly…

Astrophysics of Galaxies · Physics 2025-11-07 Kenneth J. Duncan

We propose a Multimodal Machine Learning method for estimating the Photometric Redshifts of quasars (PhotoRedshift-MML for short), which has long been the subject of many investigations. Our method includes two main models, i.e. the feature…

Astrophysics of Galaxies · Physics 2022-11-09 Shuxin Hong , Zhiqiang Zou , A-Li Luo , Xiao Kong , Wenyu Yang , Yanli Chen

We develop an automated technique to measure quasar redshifts in the Baryon Oscillation Spectroscopic Survey (BOSS) of the Sloan Digital Sky Survey (SDSS). Our technique is an extension of an earlier Gaussian process method for detecting…

Astrophysics of Galaxies · Physics 2020-09-16 Leah Fauber , Ming-Feng Ho , Simeon Bird , Christian R. Shelton , Roman Garnett , Ishita Korde

We present the VST ATLAS Quasar Survey, consisting of $\sim1,229,000$ quasar (QSO) candidates with $16<g<22.5$ over $\sim4700$ deg$^2$. The catalogue is based on VST ATLAS$+$NEOWISE imaging surveys and aims to reach a QSO sky density of…

We apply simple optical and SZ cluster finders to mock galaxy catalogues and SZ flux maps created from dark matter halos in a (1 Gpc/h)^3 dark matter simulation, at redshifts 0.5 and 0.9. At each redshift, the two catalogues are then…

Astrophysics · Physics 2009-11-13 J. D. Cohn , Martin White

The impending Javalambre Physics of the accelerating universe Astrophysical Survey (J-PAS) will be the first wide-field survey of $\gtrsim$ 8500 deg$^2$ to reach the `stage IV' category. Because of the redshift resolution afforded by 54…

We present variability and multi-wavelength photometric information for the 933 known quasars in the QUEST Variability Survey. These quasars are grouped into variable and non-variable populations based on measured variability confidence…

Astrophysics · Physics 2008-11-26 Adam W. Rengstorf , Robert J. Brunner , Brian C. Wilhite

We present an unsupervised machine learning approach that can be employed for estimating photometric redshifts. The proposed method is based on a vector quantization approach called Self--Organizing Mapping (SOM). A variety of…

Instrumentation and Methods for Astrophysics · Physics 2015-06-03 M. J. Way , C. D. Klose

We investigate, using simulated galaxy catalogues, the completeness of searches for massive clusters of galaxies in redshift surveys or imaging surveys with photometric redshift estimates, i.e. what fraction of clusters (M>10^14/h Msun) are…

Astrophysics · Physics 2008-11-26 Martin White , C. S. Kochanek

Various galaxy merger detection methods have been applied to diverse datasets. However, it is difficult to understand how they compare. We aim to benchmark the relative performance of machine learning (ML) merger detection methods. We…

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