2010A&A...510A..45C


C.D.S. - SIMBAD4 rel 1.7 - 2020.05.29CEST03:10:31

2010A&A...510A..45C - Astronomy and Astrophysics, volume 510, A45-45 (2010/2-1)

Non-parametric deprojection of surface brightness profiles of galaxies in generalised geometries.

CHAKRABARTY D.

Abstract (from CDS):

We present a new Bayesian non-parametric deprojection algorithm DOPING (Deprojection of Observed Photometry using an INverse Gambit), that is designed to extract 3-D luminosity density distributions ρ from observed surface brightness maps I, in generalised geometries, while taking into account changes in intrinsic shape with radius, using a penalised likelihood approach and an Markov Chain Monte Carlo optimiser. We provide the most likely solution to the integral equation that represents deprojection of the measured I to ρ. In order to keep the solution modular, we choose to express ρ as a function of the line-of-sight (LOS) coordinate z. We calculate the extent of the system along the z-axis, for a given point on the image that lies within an identified isophotal annulus. The extent along the LOS is binned and density is held a constant over each such z-bin. The code begins with a seed density and at the beginning of an iterative step, the trial ρ is updated. Comparison of the projection of the current choice of ρ and the observed I defines the likelihood function (which is supplemented by Laplacian regularisation), the maximal region of which is sought by the optimiser (Metropolis Hastings). The algorithm is successfully tested on a set of test galaxies, the morphology of which ranges from an elliptical galaxy with varying eccentricity to an infinitesimally thin disk galaxy marked by an abruptly varying eccentricity profile. Applications are made to faint dwarf elliptical galaxy Ic 3019 and another dwarf elliptical that is characterised by a central spheroidal nuclear component superimposed upon a more extended flattened component. The result of deprojection of the X-ray image of cluster A1413 - assumed triaxial - the axial ratios and inclination of which are taken from the literature, is also presented.

Abstract Copyright:

Journal keyword(s): methods: statistical - galaxies: fundamental parameters

Status at CDS:  

Simbad objects: 8

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Number of rows : 8

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 14746 1
2 ACO 1413 ClG 11 55 18.0 +23 24 19           ~ 379 0
3 IC 3019 GiG 12 09 22.257 +13 59 32.73   15.0       ~ 94 0
4 M 85 GiP 12 25 24.053 +18 11 27.89   10.2       ~ 600 0
5 NGC 4442 GiG 12 28 03.893 +09 48 13.03   11.2       ~ 260 0
6 IC 3381 LSB 12 28 14.854 +11 47 23.69   14.42       ~ 140 1
7 NGC 4762 LIN 12 52 56.049 +11 13 50.88   11.1       ~ 334 0
8 IC 3881 GiC 12 54 48.688 +19 10 42.05   14.1       ~ 71 0

    Equat.    Gal    SGal    Ecl

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2020.05.29-03:10:31

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