Peter E. Freeman
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View article: Deep generative models for galaxy image simulations
Deep generative models for galaxy image simulations Open
Image simulations are essential tools for preparing and validating the analysis of current and future wide-field optical surveys. However, the galaxy models used as the basis for these simulations are typically limited to simple parametric…
View article: The close binary fraction as a function of stellar parameters in APOGEE: a strong anticorrelation with α abundances
The close binary fraction as a function of stellar parameters in APOGEE: a strong anticorrelation with α abundances Open
We use observations from the Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey to explore the relationship between stellar parameters and multiplicity. We combine high-resolution repeat spectroscopy for 41 363 dwarf an…
View article: Evaluation of probabilistic photometric redshift estimation approaches for The Rubin Observatory Legacy Survey of Space and Time (LSST)
Evaluation of probabilistic photometric redshift estimation approaches for The Rubin Observatory Legacy Survey of Space and Time (LSST) Open
Many scientific investigations of photometric galaxy surveys require redshift estimates, whose uncertainty properties are best encapsulated by photometric redshift (photo-z) posterior probability density functions (PDFs). A plethora of pho…
View article: Deep Generative Model Samples
Deep Generative Model Samples Open
This dataset contains the main results of Deep Generative Models for Galaxy Image Simulations (Lanusse et al. 2020). It consists of tuples of postage stamps of HST/ACS COSMOS galaxies, corresponding parametric light profiles, and samples f…
View article: Deep Generative Model Samples
Deep Generative Model Samples Open
This dataset contains the main results of Deep Generative Models for Galaxy Image Simulations (Lanusse et al. 2020). It consists of tuples of postage stamps of HST/ACS COSMOS galaxies, corresponding parametric light profiles, and samples f…
View article: Facilitating Authentic Practice for Early Undergraduate Statistics Students
Facilitating Authentic Practice for Early Undergraduate Statistics Students Open
In current curricula, authentic statistical practice generally only occurs in capstone projects undertaken by advanced undergraduate and Master’s students. We argue that deferring practice is a mistake: undergraduate students should achiev…
View article: Automated distant galaxy merger classifications from Space Telescope images using the Illustris simulation
Automated distant galaxy merger classifications from Space Telescope images using the Illustris simulation Open
We present image-based evolution of galaxy mergers from the Illustris cosmological simulation at 12 time-steps over 0.5 < z < 5. To do so, we created approximately one million synthetic deep Hubble Space Telescope and James Webb Spac…
View article: Astro2020 Science White Paper: The Next Decade of Astroinformatics and Astrostatistics
Astro2020 Science White Paper: The Next Decade of Astroinformatics and Astrostatistics Open
Over the past century, major advances in astronomy and astrophysics have been largely driven by improvements in instrumentation and data collection. With the amassing of high quality data from new telescopes, and especially with the advent…
View article: Combining novel research and community-engaged learning in an undergraduate physiology laboratory course
Combining novel research and community-engaged learning in an undergraduate physiology laboratory course Open
To better prepare physiology students for 21st century careers, we incorporated classroom-based undergraduate research experiences and service learning/community-engaged learning (SLCE) into a college-level physiology laboratory course. Th…
View article: Intrinsic alignment in redMaPPer clusters – II. Radial alignment of satellites towards cluster centres
Intrinsic alignment in redMaPPer clusters – II. Radial alignment of satellites towards cluster centres Open
We study the orientations of satellite galaxies in redMaPPer clusters constructed from the Sloan Digital Sky Survey at 0.1 < z < 0.35 to determine whether there is any preferential tendency for satellites to point radially towards cluster …
View article: Local two-sample testing: a new tool for analysing high-dimensional astronomical data
Local two-sample testing: a new tool for analysing high-dimensional astronomical data Open
Modern surveys have provided the astronomical community with a flood of\nhigh-dimensional data, but analyses of these data often occur after their\nprojection to lower-dimensional spaces. In this work, we introduce a local\ntwo-sample hypo…
View article: Photo-$z$ estimation: An example of nonparametric conditional density estimation under selection bias
Photo-$z$ estimation: An example of nonparametric conditional density estimation under selection bias Open
Redshift is a key quantity for inferring cosmological model parameters. In photometric redshift estimation, cosmologists use the coarse data collected from the vast majority of galaxies to predict the redshift of individual galaxies. To pr…
View article: Prediction of galaxy ellipticities and reduction of shape noise in cosmic shear measurements
Prediction of galaxy ellipticities and reduction of shape noise in cosmic shear measurements Open
The intrinsic scatter in the ellipticities of galaxies about the mean shape, known as "shape noise," is the most important source of noise in weak lensing shear measurements. Several approaches to reducing shape noise have recently been pu…
View article: A unified framework for constructing, tuning and assessing photometric redshift density estimates in a selection bias setting
A unified framework for constructing, tuning and assessing photometric redshift density estimates in a selection bias setting Open
Photometric redshift estimation is an indispensable tool of precision cosmology. One problem that plagues the use of this tool in the era of large-scale sky surveys is that the bright galaxies that are selected for spectroscopic observatio…
View article: Testing hypotheses about individual variation in plasma corticosterone in free-living salamanders
Testing hypotheses about individual variation in plasma corticosterone in free-living salamanders Open
In vertebrates, many responses to stress as well as homeostatic maintenance of basal metabolism are regulated by plasma glucocorticoid hormones (GCs). Despite having crucial functions, levels of GCs are typically variable among individuals…
View article: Detecting effects of filaments on galaxy properties in the Sloan Digital Sky Survey III
Detecting effects of filaments on galaxy properties in the Sloan Digital Sky Survey III Open
We study the effects of filaments on galaxy properties in the Sloan Digital Sky Survey (SDSS) Data Release 12 using filaments from the ‘Cosmic Web Reconstruction’ catalogue (Chen et al. 2015a), a publicly available filament catalogue for S…
View article: Intrinsic alignments in redMaPPer clusters – I. Central galaxy alignments and angular segregation of satellites
Intrinsic alignments in redMaPPer clusters – I. Central galaxy alignments and angular segregation of satellites Open
The shapes of cluster central galaxies are not randomly oriented, but rather exhibit coherent alignments with the shapes of their parent clusters as well as with the surrounding large-scale structures. In this work, we aim to identify the …
View article: Cosmic web reconstruction through density ridges: catalogue
Cosmic web reconstruction through density ridges: catalogue Open
We construct a catalogue for filaments using a novel approach called SCMS\n(subspace constrained mean shift; Ozertem & Erdogmus 2011; Chen et al. 2015).\nSCMS is a gradient-based method that detects filaments through density ridges\n(smoot…
View article: Beyond spheroids and discs: classifications of CANDELS galaxy structure at 1.4 <<i>z</i>< 2 via principal component analysis
Beyond spheroids and discs: classifications of CANDELS galaxy structure at 1.4 <<i>z</i>< 2 via principal component analysis Open
Important but rare and subtle processes driving galaxy morphology and star formation may be missed by traditional spiral, elliptical, irregular or Se´rsic bulge/disc classifications. To overcome this limitation, we use a principal componen…
View article: Investigating galaxy-filament alignments in hydrodynamic simulations using density ridges
Investigating galaxy-filament alignments in hydrodynamic simulations using density ridges Open
In this paper, we study the filamentary structures and the galaxy alignment along filaments at redshift z = 0.06 in the MassiveBlack-II simulation, a state-of-the-art, high-resolution hydrodynamical cosmological simulation which includes s…
View article: Cosmic web reconstruction through density ridges: method and algorithm
Cosmic web reconstruction through density ridges: method and algorithm Open
The detection and characterization of filamentary structures in the cosmic web allows cosmologists to constrain parameters that dictate the evolution of the Universe. While many filament estimators have been proposed, they generally lack e…
View article: Diverse structural evolution at<i>z</i> > 1 in cosmologically simulated galaxies
Diverse structural evolution at<i>z</i> > 1 in cosmologically simulated galaxies Open
From mock Hubble Space Telescope images, we quantify non-parametric statistics of galaxy morphology, thereby predicting the emergence of relationships among stellar mass, star formation, and observed rest-frame optical structure at 1 < z <…