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As recent observations of the molecular discs in spiral galaxies point to the existence of a diffuse, low-density thick molecular disc along with the prominent thin one, we investigate the observational signatures of this thick disc by…

Astrophysics of Galaxies · Physics 2020-07-08 Narendra Nath Patra

We present a new method to construct fully self-consistent equilibrium models of multi-component disc galaxies similar to the Milky Way. We define distribution functions for the stellar disc and dark halo that depend on phase space position…

Astrophysics of Galaxies · Physics 2015-07-03 T. Piffl , Z. Penoyre , J. Binney

State-of-the-art cosmological hydrodynamical simulations have star particles with typical mass between $\sim 10^8$ and $\sim 10^3$ M$_{\odot}$ according to resolution, and treat them as simple stellar populations. On the other hand,…

Astrophysics of Galaxies · Physics 2018-07-31 Milena Valentini , Alessandro Bressan , Stefano Borgani , Giuseppe Murante , Léo Girardi , Luca Tornatore

We propose an ambitious new method that models the intracluster medium in clusters of galaxies as a set of X-ray emitting smoothed particles of plasma. Each smoothed particle is described by a handful of parameters including temperature,…

Astrophysics · Physics 2010-11-05 J. R. Peterson , P. J. Marshall , K. Andersson

This paper describes a method for quantitatively comparing an N-body model with a sample of discrete kinematic data. The comparison has two stages: (i) finding the optimum scaling and orientation of the model relative to the data; and (ii)…

Astrophysics · Physics 2009-10-30 Prasenjit Saha

Quantitative morphological and structural parameters are estimated for galaxies detected in HST observations of WFPC2 survey fields. A modeling approach based on maximum likelihood has been developed for two-dimensional decomposition of…

Astrophysics · Physics 2007-05-23 Kavan U. Ratnatunga , Richard E. Griffiths , Eric J. Ostrander

If properly calibrated, the shapes of galaxy clusters can be used to investigate many physical processes: from feedback and quenching of star formation, to the nature of dark matter. Theorists frequently measure shapes using moments of…

Cosmology and Nongalactic Astrophysics · Physics 2020-11-11 David Harvey , Andrew Robertson , Sut-Ieng Tam , Mathilde Jauzac , Richard Massey , Jason Rhodes , Ian G. McCarthy

Using three-dimensional stellar kinematic data from simulated galaxies, we examine the efficacy of a Jeans equation analysis in reconstructing the total disk surface density, including the dark matter, at the "Solar" radius. Our simulation…

Astrophysics of Galaxies · Physics 2016-01-18 G. N. Candlish , R. Smith , C. Moni Bidin , B. K. Gibson

We present a novel technique for estimating disk parameters (the centre and the radius) from its 2D image. It is based on the maximal likelihood approach utilising both edge pixels coordinates and the image intensity gradients. We emphasise…

Image and Video Processing · Electrical Eng. & Systems 2020-09-03 Matwey V. Kornilov

We present accurate models of the gravitational potential produced by a radially exponential disk mass distribution. The models are produced by combining three separate Miyamoto-Nagai disks. Such models have been used previously to model…

Astrophysics of Galaxies · Physics 2015-02-10 Rory Smith , Chris Flynn , Graeme N. Candlish , Michael Fellhauer , Brad K. Gibson

Our understanding of how the size of galaxies has evolved over cosmic time is based on the use of the half-light (effective) radius as a size indicator. Although the half-light radius has many advantages for structurally parameterising…

Astrophysics of Galaxies · Physics 2023-12-14 Fernando Buitrago , Ignacio Trujillo

We performed 3-dimensional N-body/SPH simulations to study how mass resolution and other model parameters such as the star formation efficiency parameter, C* and the threshold density, nth affect structures of the galactic gaseous/stellar…

We use numerical simulations of critically-closed cold dark matter (CDM) models to study the effects of numerical resolution on observable quantities. We study simulations with up to $256^3$ particles using the particle-mesh (PM) method and…

Astrophysics · Physics 2009-10-22 James M. Gelb , Edmund Bertschinger

We present a method for fitting orbit-superposition models to the kinematics of discrete stellar systems when the available stellar sample has been filtered by a known selection function. The fitting method can be applied to any model in…

Astrophysics of Galaxies · Physics 2019-01-23 John Magorrian

The observations of external galaxies are projected to the 2D sky plane. Reconstructing the 3D intrinsic density distribution of a galaxy from the 2D image is challenging, especially for barred galaxies, but is a critical step for…

Astrophysics of Galaxies · Physics 2021-10-22 Behzad Tahmasebzadeh , Ling Zhu , Juntai Shen , Ortwin Gerhard , Yujing Qin

Extreme adaptive optics instruments have revealed exquisite details on debris discs, allowing to extract the optical properties of the dust particles such as the phase function, the degree of polarisation and the spectral reflectance. These…

We propose a two dimensional galaxy fitting algorithm to extract parameters of the bulge, disk, and a central point source from broad band images of galaxies. We use a set of realistic galaxy parameters to construct a large number of model…

Astrophysics · Physics 2009-10-30 Yogesh Wadadekar , Braxton Robbason , Ajit Kembhavi

(Abridged) We describe a new iterative approach for the realization of equilibrium N-body systems for given density distributions. Our method uses elements of Schwarzschild's technique and of the made-to-measure method, but is based on a…

Cosmology and Nongalactic Astrophysics · Physics 2014-08-20 Denis Yurin , Volker Springel

An efficient simulation-based methodology is proposed for the rolling window estimation of state space models, called particle rolling Markov chain Monte Carlo (MCMC) with double block sampling. In our method, which is based on Sequential…

Computation · Statistics 2021-09-17 Naoki Awaya , Yasuhiro Omori

We investigate the consistency of visual morphological classifications of galaxies by comparing classifications for 831 galaxies from six independent observers. The galaxies were classified on laser print copy images or on computer screen…

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