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The inverse problem of extracting the stellar population content of galaxy spectra is analysed here from a basic standpoint based on information theory. By interpreting spectra as probability distribution functions, we find that galaxy…

Astrophysics of Galaxies · Physics 2023-02-02 Ignacio Ferreras , Ofer Lahav , Rachel S. Somerville , Joseph Silk

We introduce a method for producing a galaxy sample unbiased by surface brightness and stellar mass, by selecting star-forming galaxies via the positions of core-collapse supernovae (CCSNe). Whilst matching $\sim$2400 supernovae from the…

Astrophysics of Galaxies · Physics 2019-01-23 Thomas M. Sedgwick , Ivan K. Baldry , Philip A. James , Lee S. Kelvin

Stellar spectral classification has been highly useful in the study of stars. While there is a currently accepted spectral classification system for carbon stars, the subset of Hydrogen-deficient Carbon (HdC) stars has not been well…

The two currently largest all-sky photometric datasets, WISE and SuperCOSMOS, were cross-matched by Bilicki et al. (2016) (B16) to construct a novel photometric redshift catalogue on 70% of the sky. Galaxies were therein separated from…

Astrophysics of Galaxies · Physics 2016-11-30 T. Krakowski , K. Małek , M. Bilicki , A. Pollo , M. Krupa , A. Kurcz

The Galactic O-Star Spectroscopic Survey (GOSSS) is obtaining high quality R~2500 blue-violet spectroscopy of all Galactic stars ever classified as of O type with B < 12 and a significant fraction of those with B = 12-14. As of June 2013,…

We present a novel approach to photometric redshifts, one that merges the advantages of both the template fitting and empirical fitting algorithms, without any of their disadvantages. This technique derives a set of templates, describing…

Astrophysics · Physics 2009-10-31 I. Csabai , A. J. Connolly , A. S. Szalay , T. Budavari

In the modern galaxy surveys photometric redshifts play a central role in a broad range of studies, from gravitational lensing and dark matter distribution to galaxy evolution. Using a dataset of about 25,000 galaxies from the second data…

Instrumentation and Methods for Astrophysics · Physics 2017-06-14 Stefano Cavuoti , Crescenzo Tortora , Massimo Brescia , Giuseppe Longo , Mario Radovich , Nicola R. Napolitano , Valeria Amaro , Civita Vellucci

We present a classification of galaxies in the Pan-STARRS1 (PS1) 3$\pi$ survey based on their recent star formation history and morphology. Specifically, we train and test two Random Forest (RF) classifiers using photometric features…

High Energy Astrophysical Phenomena · Physics 2020-10-21 A. Baldeschi , A. Miller , M. Stroh , R. Margutti , D. L. Coppejans

Understanding how the physical properties of galaxies (e.g. their spectral type or age) evolve as a function of redshift relies on having an accurate representation of galaxy spectral energy distributions. While it has been known for some…

We present a massive spectroscopic survey of Galactic O stars, GOSSS, based on new, high signal-to-noise ratio, R~2500 blue-violet digital observations from both hemispheres. The sample size and selection criteria; the relationship between…

Solar and Stellar Astrophysics · Physics 2010-10-29 J. Maíz Apellániz , A. Sota , N. R. Walborn , E. J. Alfaro , R. H. Barbá , N. I. Morrell , R. C. Gamen , J. I. Arias , M. Penadés Ordaz

The Information Bottleneck (IB) principle offers an information-theoretic framework for analyzing the training process of deep neural networks (DNNs). Its essence lies in tracking the dynamics of two mutual information (MI) values: between…

Machine Learning · Computer Science 2024-05-10 Ivan Butakov , Alexander Tolmachev , Sofia Malanchuk , Anna Neopryatnaya , Alexey Frolov , Kirill Andreev

The morphological classification of galaxies provides vital physical information about the orbital motions of stars in galaxies, and correlates in interesting ways with star formation history, and other physical properties. Galaxy…

Astrophysics of Galaxies · Physics 2025-02-14 Karen Masters

We present a catalog of detailed visual classifications for 14034 galaxies in the Sloan Digital Sky Survey (SDSS) Data Release 4 (DR4). Our sample includes nearly all spectroscopically-targeted galaxies in the redshift range 0.01<z<0.1 down…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 Preethi B. Nair , Roberto G. Abraham

Accurate relative spectrophotometry is critical for many science applications. Small wavelength scale residuals in the flux calibration can significantly impact the measurements of weak emission and absorption features in the spectra. Using…

Instrumentation and Methods for Astrophysics · Physics 2011-10-14 Renbin Yan

The Information Bottleneck (IB) objective uses information theory to formulate a task-performance versus robustness trade-off. It has been successfully applied in the standard discriminative classification setting. We pose the question…

Machine Learning · Computer Science 2021-01-13 Lynton Ardizzone , Radek Mackowiak , Carsten Rother , Ullrich Köthe

The next generation of proposed galaxy surveys will increase the number of galaxies with photometric redshifts by two orders of magnitude, drastically expanding both redshift range and detection threshold from the current state of the art.…

Cosmology and Nongalactic Astrophysics · Physics 2011-02-11 A. E. Schulz

We revisit the scaling relations and star-forming histories of local elliptical galaxies using a novel selection method applied to the Sloan Digital Sky Survey DR7. We combine two probability-based automated spectroscopic and morphological…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-03 J. A. L. Aguerri , M. Huertas-Company , J. Sánchez Almeida , C. Munoz-Tunon

We present the relation between galaxy structure and spectral type, using a K-selected galaxy sample at 0.5<z<2.0. Based on similarities between the UV-to-NIR spectral energy distributions, we classify galaxies into 32 spectral types. The…

Astrophysics of Galaxies · Physics 2016-02-17 Michael Yano , Mariska Kriek , Arjen van der Wel , Katherine Whitaker

We present a new technique for measuring the integrated galaxy light (IGL) with stacked image data from the Dark Energy Survey (DES). We extract $1\times1$ arcminute cutouts from nearly 100,000 randomly selected positions in the g, r, i, z,…

Cosmology and Nongalactic Astrophysics · Physics 2025-06-11 Jenna E. Moore , Seth H. Cohen , Philip Mauskopf , Evan Scannapieco
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