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To determine the precise positions of stars in CCD frames, various centering algorithms have been proposed for astrometry. The effective point spread function (ePSF) and the Gaussian centering algorithms are two representative centering…

Instrumentation and Methods for Astrophysics · Physics 2021-12-28 F. R. Lin , Q. Y. Peng , Z. J. Zheng , B. F. Guo , Y. J. Shang

The large scale infall of galaxies around massive clusters provides a potentially powerful diagnostic of structure growth, dark energy, and cosmological deviations from General Relativity. We develop and test a method to recover galaxy…

Cosmology and Nongalactic Astrophysics · Physics 2013-04-08 Ying Zu , David H. Weinberg

In the context of measuring structure and morphology of intermediate redshift galaxies with recent HST/ACS surveys, we tune, test, and compare two widely used fitting codes (GALFIT and GIM2D) for fitting single-component Sersic models to…

I start by providing an updated summary of the penalized pixel-fitting (pPXF) method, which is used to extract the stellar and gas kinematics, as well as the stellar population of galaxies, via full spectrum fitting. I then focus on the…

Astrophysics of Galaxies · Physics 2017-01-11 Michele Cappellari

Calibration precision is currently a limiting systematic in 21 cm cosmology experiments. While there are innumerable calibration approaches, most can be categorized as either `sky-based,' relying on an extremely accurate model of…

Instrumentation and Methods for Astrophysics · Physics 2021-03-17 Ruby Byrne , Miguel F. Morales , Bryna Hazelton , Michael Wilensky

Molecular line emissions are commonly used to trace the distribution and properties of molecular Interstellar Medium (ISM). However, the emissions are heavily blended on the Galactic disk toward the inner Galaxy because of the relatively…

Astrophysics of Galaxies · Physics 2024-10-07 Haoran Feng , Zhiwei Chen , Zhibo Jiang , James S. Urquhart

Detecting and characterizing the Epoch of Reionization and Cosmic Dawn via the redshifted 21-cm hyperfine line of neutral hydrogen will revolutionize the study of the formation of the first stars, galaxies, black holes and intergalactic gas…

Cosmology and Nongalactic Astrophysics · Physics 2018-05-23 F. G. Mertens , A. Ghosh , L. V. E. Koopmans

We present a methodology for ensuring the robustness of our analysis pipeline in separating the global 21-cm hydrogen cosmology signal from large systematics based on singular value decomposition (SVD) of training sets. We show how…

Cosmology and Nongalactic Astrophysics · Physics 2021-03-03 Neil Bassett , David Rapetti , Keith Tauscher , Jack Burns , Joshua Hibbard

We present a novel algorithm based on a Bayesian method for 2D tilted-ring analysis of disk galaxy velocity fields. Compared to the conventional algorithms based on a chi-squared minimisation procedure, this new Bayesian-based algorithm…

Astrophysics of Galaxies · Physics 2017-11-29 Se-Heon Oh , Lister Staveley-Smith , Kristine Spekkens , Peter Kamphuis , Bärbel S. Koribalski

For the $\pbar p$ and $pp$ systems, we have used all of the extensive data of the Particle Data Group[K. Hagiwara {\em et al.} (Particle Data Group), Phys. Rev. D 66, 010001 (2002).]. We then subject these data to a screening process, the…

High Energy Physics - Phenomenology · Physics 2008-11-26 Martin M. Block

We introduce a self-calibration method that can be applied to the intrinsic ellipticity--intrinsic ellipticity (II) and gravitational shear -- intrinsic ellipticity (GI) types of intrinsic alignment of galaxies. The method combines previous…

Cosmology and Nongalactic Astrophysics · Physics 2018-12-05 Ji Yao , Mustapha Ishak , M. A. Troxel

Optical emission line diagnostics, which are a common tool to constrain the properties of the interstellar medium (ISM) of galaxies, become progressively inaccessible at higher redshifts for ground-based facilities. Far-infrared (FIR)…

Astrophysics of Galaxies · Physics 2024-07-17 Alice Schimek , Claudia Cicone , Sijing Shen , Davide Decataldo , Pamela Klaassen , Lucio Mayer

Hydrogen, the most abundant element in the universe, is crucial for understanding galaxy formation and evolution. The 21 cm neutral atomic hydrogen - HI spectral line maps the gas kinematics within galaxies, providing key insights into…

We present the final data release of observations of lambda 21-cm emission from Galactic neutral hydrogen over the entire sky, merging the Leiden/Dwingeloo Survey (LDS: Hartmann & Burton, 1997) of the sky north of delta = -30 deg with the…

We have analyzed the properties of metals in the high redshift intergalactic medium using a novel objective pixel optical depth technique on a sample of extremely high signal-to-noise Keck HIRES and ESI spectra of 26 quasars between…

Astrophysics · Physics 2008-11-26 Antoinette Songaila

We resolve the kinematic distance ambiguity for 266 inner Galaxy HII regions out of a sample of 291 using existing HI and 13CO sky surveys. Our sample contains all HII regions with measured radio recombination line (RRL) emission over the…

Astrophysics · Physics 2008-12-18 L. D. Anderson , T. M. Bania

We searched for 21-cm absorption associated with the z_abs = 1.3647 absorption system toward PKS 0237-233 using the GMRT. A high quality UVES spectrum shows that C I and C I* are detected at this redshift together with C II*, Mg I, Mg II,…

Astrophysics · Physics 2008-11-26 Raghunathan Srianand , Neeraj Gupta , Patrick Petitjean

The advent of new sub-millimeter observational facilities has stimulated the desire to model the sub-mm line emission of galaxies within cosmological galaxy formation models. This is typically done in post-processing by applying…

Astrophysics of Galaxies · Physics 2018-11-14 Gergö Popping , Desika Narayanan , Rachel S. Somerville , Andreas L. Faisst , Mark R. Krumholz

A systematic search for HI 21-cm absorption in Quasar-Galaxy Pairs (QGPs) provides a powerful means to map the distribution of cold gas around high-redshift star-forming galaxies. Fiber spectroscopy of high-redshift quasars enables the…

Astrophysics of Galaxies · Physics 2026-01-06 Labanya Kumar Guha , Raghunathan Srianand , Rajeshwari Dutta

Expanding upon the work of Way and Srivastava 2006 we demonstrate how the use of training sets of comparable size continue to make Gaussian process regression (GPR) a competitive approach to that of neural networks and other least-squares…

Instrumentation and Methods for Astrophysics · Physics 2009-11-09 M. J. Way , L. V. Foster , P. R. Gazis , A. N. Srivastava