J/A+A/681/A15 Nube dark galaxy HiPERCAM urgiz images (Montes+, 2024)
An almost dark galaxy with the mass of the Small Magellanic Cloud.
Montes M., Trujillo I., Karunakaran A., Infante-Sainz R., Spekkens K.,
Golini G., Beasley M., Cebrian M., Chamba N., D'Onofrio M., Kelvin L.,
Roman J.
<Astron. Astrophys. 681, A15 (2024)>
=2024A&A...681A..15M 2024A&A...681A..15M (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies ; Photometry, SDSS
Keywords: galaxies: dwarf - dark matter - galaxies: photometry -
galaxies: structure - galaxies: formation
Abstract:
Almost Dark Galaxies are objects that have eluded detection by
traditional surveys such as the Sloan Digital Sky Survey (SDSS). The
low surface brightness of these galaxies (µr(0)>26mag/arcsec2),
and hence their low surface stellar mass density (a few solar masses
per pc2 or less), suggests that the energy density released by
baryonic feedback mechanisms is inefficient in modifying the
distribution of the dark matter halos they inhabit. For this reason,
almost dark galaxies are particularly promising for probing the
microphysical nature of dark matter. In this paper, we present the
serendipitous discovery of Nube, an almost dark galaxy with
<µV>e∼26.7mag/arcsec2. The galaxy was identified using deep
optical imaging from the IAC Stripe82 Legacy Project. Follow-up
observations with the 100m Green Bank Telescope strongly suggest that
the galaxy is at a distance of 107Mpc. Ultra-deep multi-band
observations with the 10.4m Gran Telescopio Canarias favour an age of
∼10Gyr and a metallicity of [Fe/H]~-1.1. With a stellar mass of
∼4x108M_☉) and a half-mass radius of Re=6.9kpc (corresponding to
an effective surface density of <{SIGMA}>e∼0.9 M☉/pc2), Nube
is the most massive and extended object of its kind discovered so far.
The galaxy is ten times fainter and has an effective radius three
times larger than typical ultra-diffuse galaxies with similar stellar
masses. Galaxies with comparable effective surface brightness within
the Local Group have very low mass (tens of 105M☉) and compact
structures (effective radius Re<1kpc). Current cosmological
simulations within the cold dark matter scenario, including baryonic
feedback, do not reproduce the structural properties of Nube. However,
its highly extended and flattened structure is consistent with a
scenario where the dark matter particles are ultra-light axions with a
mass of mB=(0.8+0.4-0.2)x10-23eV.
Description:
Deep optical multi-band imaging of Nube was performed using
HiPERCAM. HiPERCAM is a quintuplebeam, high-speed astronomical imager
capable of simultaneously imaging celestial objects in five different
Sloan filters (u, g, r, i, z). The image area of each of the five CCDs
is 2048x1024 pixels (2.7'x1.4'; 1pixel=0.08") divided into four
channels of 1024x512 pixels each. Nube was observed on 9 and 10
January 2019.
We present HiPERCAM data of Nube. The zero points, zeropoint errors
and pixels scale is in the header.
Objects:
-----------------------------------------
RA (2000) DE Designation(s)
-----------------------------------------
01 23 27.37 -00 37 27.83 Nube
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 93 5 List of fits images
fits/* . 5 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- 34 I5 Kibyte size Size of FITS file
36- 71 A36 --- FileName Name of FITS file, in subdirectory fits
73- 93 A21 --- Title Title of the FITS file
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Acknowledgements:
Mireia Montes, mireia.montes.quiles(at)gmail.com
(End) Patricia Vannier [CDS] 03-Nov-2023