J/A+A/691/A65 Smallest Scale of Hierarchy Survey (SSH) III (Sacchi+, 2024)
The Smallest Scale of Hierarchy Survey (SSH).
III. Dwarf-dwarf satellite merging phenomena in the low-mass regime.
Sacchi E., Bellazzini M., Annibali F., Tosi M., Beccari G., Cannon J.M.,
Hunter L.C., Paris D., Roychowdhury S., Schisgal L., van Zee L., Cignoni M.,
Cusano F., de Jong R.S., Hunt L., Pascale R.
<Astron. Astrophys. 691, A65 (2024)>
=2024A&A...691A..65S 2024A&A...691A..65S (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, photometry ; Photometry, SDSS
Keywords: galaxies: dwarf - galaxies: formation - galaxies: interactions -
galaxies: irregular - galaxies: stellar content
Abstract:
We present new deep, wide-field imaging data from the Large Binocular
Telescope (LBT) in g and r bands from the Smallest Scale of Hierarchy
Survey (SSH) that reveal previously undetected tidal features and
stellar streams in the outskirts of six dwarf irregular galaxies (NGC
5238, UGC 6456, UGC 6541, UGC 7605, UGC 8638, and UGC 8760) with
stellar masses in the range 1.2x107M☉ to 1.4x108M☉.
The six dwarfs are located 1-2Mpc away from large galaxies, which
implies that the observed distortions are unlikely to be due to tidal
effects from a nearby, massive companion. At the distances of ∼3-4Mpc
at which the dwarfs lie, the identified tidal features are all
resolved into individual stars in the LBT images and appear to consist
of a population older than 1-2Gyr. This excludes the possibility that
they result from irregular and asymmetric star formation episodes that
are common in gas-rich dwarf galaxies. The most plausible explanation
is that we witness the hierarchical merging assembly of these dwarfs
with their satellite populations. This scenario is also supported by
the peculiar morphology and disturbed velocity field of their HI
component. From the SSH sample, we estimate that a fraction of ∼13% of
the late-type dwarfs show signs of merging with satellites. This is in
agreement with other recent independent studies and theoretical
predictions within the {LAMNDA}CDM cosmological framework.
Description:
Reduced LBT images (g and r channels of LBC) of the 6 dwarf irregular
galaxies analyzed in the paper.
Objects:
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RA (2000) DE Designation(s)
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13 34 42.51 +51 36 49.1 NGC 5238 = UGC 8565
11 27 59.89 +78 59 39.0 UGC 6456 = MCG+13-08-058
11 33 29.11 +49 14 17.4 UGC 6541 = Mrk 178
12 28 38.74 +35 43 02.9 UGC 7605 = MCG+06-27-058
13 39 19.34 +24 46 27.7 UGC 8638 = MCG+04-32-018
13 50 51.31 +38 01 14.9 UGC 8760 = MCG+06-30-105
-------------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 83 12 List of fits images
fits/* . 12 Individual fit 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- 24 F5.3 arcsec/pix scale Scale of the image
26- 29 I4 --- Nx Number of pixels along X-axis
31- 34 I4 --- Ny Number of pixels along Y-axis
36- 41 I6 Kibyte size Size of FITS file
43- 61 A19 --- FileName Name of FITS file, in subdirectory fits
63- 83 A21 --- Title Title of the FITS file
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Acknowledgements:
Elena Sacchi, esacchi(at)aip.de
References:
Annibali et al., Paper I 2020MNRAS.491.5101A 2020MNRAS.491.5101A
Annibali et al., Paper II 2022MNRAS.512.1781A 2022MNRAS.512.1781A
(End) Patricia Vannier [CDS] 24-Sep-2024