J/A+A/640/A38 gr images of 20 isolated early-type galaxies (Rampazzo+, 2020)
Morphology and surface photometry of a sample of isolated early-type galaxies
from deep imaging.
Rampazzo R., Omizzolo A., Uslenghi M., Roman J., Mazzei P.,
Verdes-Montenegro L., Marino A., Jones M.G.
<Astron. Astrophys. 640, A38 (2020)>
=2020A&A...640A..38R 2020A&A...640A..38R (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, photometry ; Photometry, SDSS
Keywords: galaxies: elliptical and lenticular, cD - galaxies: photometry -
galaxies: interaction - galaxies: evolutions
Abstract:
Isolated early-type galaxies are evolving in unusually poor
environments for this morphological family, which is typical of
cluster inhabitants. We investigate the mechanisms driving the
evolution of these galaxies.
Several studies indicate that interactions, accretions, and merging
episodes leave their signature on the galaxy structure, from the
nucleus down to the faint outskirts. We focus on revealing such
signatures, if any, in a sample of isolated early-type galaxies, and
we quantitatively revise their galaxy classification.
We observed 20 (out of 104) isolated early-type galaxies, selected
from the AMIGA catalog, with the 4KCCD camera at the Vatican Advanced
Technology Telescope (VATT) in the Sloan Digital Sky Survey (SDSS) g
and r bands. These are the deepest observations of a sample of
isolated early-type galaxies so far: on average, the light profiles
reach µg~=28.11±0.70mag/arcsec2 and
µr~=27.36±0,68mag/arcsec2. The analysis was performed using
the AIDA package, providing point spread function-corrected 2D surface
photometry up to the galaxy outskirts. The package provides a model of
the 2D galaxy light distribution, which after model subtraction
enhances the fine and peculiar structures in the residual image of the
galaxies.
Our re-classification suggests that the sample is composed of bona
fide early-type galaxies spanning from ellipticals to late-S0s
galaxies. Most of the surface brightness profiles are best fitted with
a bulge plus disc model, suggesting the presence of an underlying disc
structure. The residuals obtained after the model subtraction show the
nearly ubiquitous presence of fine structures, such as shells, stellar
fans, rings, and tails. Shell systems are revealed in about 60% of
these galaxies.
Because interaction, accretion, and merging events are widely
interpreted as the origin of the fans, ripples, shells and tails in
galaxies, we suggest that most of these isolated early-type galaxies
have experienced such events. Because they are isolated (after
2-3Gyr), these galaxies are the cleanest environment in which to study
phenomena connected with events like these.
Description:
The sample set is composed of 20 iETGs that are included in the
Analysis of the interstellar Medium of Isolated Galaxies sample
(AMIGA, Verdes-Montenegro et al. (2005, Cat. J/A+A/436/443)), which is
a revision of the 1973 catalogue of Karachentseva (1973, Cat. VII/77).
Observations have been performed during a single run from April 9 to
April 15, 2018, at the 1.8m VATT. Photometric conditions varied
greatly: the night of 12 April was lost, as were parts of some other
nights.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 83 40 List of fits images
fits/* . 40 Individual fits images
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See also:
VII/77 : Isolated Pairs of Galaxies in Northern Hemisphere
(Karachentsev 1972)
J/A+A/436/443 : AMIGA. I. Velocities of CIG galaxies (Verdes-Montenegro+ 2005)
Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 6 A6 --- Name Galaxy name, KIGNNN, K73 NNN in Simbad
8- 16 F9.5 deg RAdeg Right Ascension of center (J2000)
17- 25 F9.5 deg DEdeg Declination of center (J2000)
27- 31 F5.3 arcsec/pix scale Scale of the image
33- 36 I4 --- Nx Number of pixels along X-axis
38- 41 I4 --- Ny Number of pixels along Y-axis
43 A1 --- Band [gr] Observed band
45- 49 I5 Kibyte size Size of FITS file
51- 63 A13 --- FileName Name of FITS file, in subdirectory fits
65- 83 A19 --- Title Title of the FITS file
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Acknowledgements:
Roberto Rampazzo, roberto.rampazzo(at)inaf.it
(End) Patricia Vannier [CDS] 10-Jun-2020