J/A+A/636/A8 Early type galaxies g-r colour fits maps (Yildiz+, 2020)
Cold gas and dust: Hunting spiral-like structures in early type galaxies.
Yildiz M.K., Peletier R.F., Duc P.-A., Serra P.
<Astron. Astrophys. 636, A8 (2020)>
=2020A&A...636A...8Y 2020A&A...636A...8Y (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, photometry
Keywords: galaxies: elliptical and lenticular, cD - galaxies: evolution -
galaxies: ISM - galaxies: photometry - galaxies: stellar content
Abstract:
Observations of neutral hydrogen (HI) and molecular gas show that 50%
of all nearby early-type galaxies (ETGs) contain some cold gas.
Molecular gas is always found in small gas discs in the central region
of the galaxy, while neutral hydrogen is often distributed in a
low-column density disc or ring typically extending well beyond the
stellar body. Dust is frequently found in ETGs as well.
The goal of our study is to understand the link between dust and cold
gas in nearby ETGs as a function of HI content.
We analyse deep optical g-r images obtained with the MegaCam camera at
the Canada-France-Hawaii Telescope for a sample of 21 HI-rich and 41
HI-poor ETGs.
We find that all HI- rich galaxies contain dust seen as absorption.
Moreover, in 57 percent of these HI-rich galaxies, the dust is
distributed in a large-scale spiral pattern. Although the dust
detection rate is relatively high in the HI-poor galaxies (59
percent), most of these systems exhibit simpler dust morphologies
without any evidence of spiral structures. We find that the HI-rich
galaxies possess more complex dust morphology extending to almost two
times larger radii than HI-poor objects. We measured the dust content
of the galaxies from the optical colour excess and find that HI-rich
galaxies contain six times more dust (in mass) than HI-poor ones. In
order to maintain the dust structures in the galaxies, continuous gas
accretion is needed, and the substantial HI gas reservoirs in the
outer regions of ETGs can satisfy this need for a long time. We find
that there is a good correspondence between the observed masses of the
gas and dust, and it is also clear that dust is present in regions
further than 3 Reff.
Our findings indicate an essential relation between the presence of
cold gas and dust in ETGs and offer a way to study the interstellar
medium in more detail than what is possible with. HI observations.
Description:
This dataset includes the g-r colour maps obtained from the g and r
band images that were taken with the MegaCam camera at the CHFT
telescope.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 82 62 List of fits images
fits/* . 62 Individual fits images
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 23 I4 --- Nx Number of pixels along X-axis
25- 28 I4 --- Ny Number of pixels along Y-axis
30- 39 A10 "date" Obs.date Observation date
41- 45 I5 Kibyte size Size of FITS file
47- 58 A12 --- FileName Name of FITS file, in subdirectory fits
60- 82 A23 --- Title Title of the FITS file
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Acknowledgements:
Mustafa Kursad Yildiz, astro.yildiz(at)gmail.com
(End) Patricia Vannier [CDS] 01-Apr-2020