J/MNRAS/504/3580 Fornax galaxy cluster NIR images & catalogs (Saifollahi+, 2021)
Ultra-compact dwarfs beyond the centre of the Fornax galaxy cluster:
hints of UCD formation in low-density environments.
Saifollahi T., Janz J., Peletier R.F., Cantiello M., Hilker M., Mieske S.,
Valentijn E.A., Venhola A., Kleijn G.V.
<Mon. Not. R. Astron. Soc., 504, 3580-3609 (2021)>
=2021MNRAS.504.3580S 2021MNRAS.504.3580S (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; Photometry, infrared
Keywords: galaxies: clusters: individual: Fornax - galaxies: dwarf -
galaxies: evolution - galaxies: star clusters: general
Abstract:
Ultra-compact dwarf galaxies (UCDs) were serendipitously discovered by
spectroscopic surveys in the Fornax cluster 20 yr ago. Nowadays, it is
commonly accepted that many bright UCDs are the nuclei of galaxies
that have been stripped. However, this conclusion might be driven by
biased samples of UCDs in high-density environments, on which most
searches are based. With the deep optical images of the Fornax Deep
Survey, combined with public near-infrared data, we revisit the UCD
population of the Fornax cluster and search for UCD candidates, for
the first time, systematically out to the virial radius of the galaxy
cluster. Our search is complete down to magnitude mg=21mag or
Mg~-10.5mag at the distance of the Fornax cluster. The UCD
candidates are identified and separated from foreground stars and
background galaxies by their optical and near-infrared colours. This
primarily utilizes the u-i/i-Ks diagram and a machine learning
technique is employed to incorporate other colour combinations to
reduce the number of contaminants. The newly identified candidates
(44) in addition to the spectroscopically confirmed UCDs (61),
increase the number of known Fornax UCD considerably (105). Almost all
of the new UCD candidates are located outside the Fornax cluster core
(360kpc), where all of the known UCDs were found. The distribution of
UCDs within the Fornax cluster shows that a population of UCDs may
form in low-density environments. This most likely challenges the
current models of UCD formation.
Description:
We present optical and near-infrared photometry of sources in the
Fornax cluster field in 6 filters (u, g, r, i, J and Ks), including
catalogues of Globular Clusters (GCs) and Ultra-Compact Dwarfs (UCDs)
in the Fornax Cluster. The optical and near-infrared images stem from
three different data sets and cover 16 square degrees out to the
virial radius of the Fornax cluster: the optical data of the Fornax
Deep Survey (FDS) in u, g, r, i and near-infrared data from the VISTA
Hemisphere Survey (VHS) in J and ESO/VISTA archival data in Ks. We
also present the final coaaded Ks images of the Fornax galaxy Cluster.
We used a deep set of Ks band observations of the Fornax cluster (ESO
programme ID 090.B-0.477(A), 092.B-0.622(A), 094.B-0.536(A),
096.B-0.532(A), PI: Munoz) that were carried out using VIRCAM, the
near-infrared camera of the VISTA telescope from October 2012 to March
2016. The final co-added frames have an average FWHM∼0.7-arcsec and a
5σ limiting magnitude of 18.4mag (∼1.0-arcsec and 17.7mag for
the Ks data of VHS).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 98 648 Catalogue of the spectroscopically
confirmed ultra-compact dwarf galaxies (UCD) and
globular clusters (GCs) in the Fornax cluster
tablea2.dat 96 4166 Catalogue of the spectroscopic foreground stars
(galaxies farthur than the Fornax Galaxy Cluster)
tablea3.dat 96 2151 Catalogue of the spectroscopic background galaxies
(Milky Way stars)
tablea4.dat 96 119153 *The UNKNOWN catalogue
tablea5.dat 123 1155 Catalogue of the UCD and GC candidates
(photometrically selected) in the Fornax cluster
tablea6.dat 123 44 Catalogue of the UCD candidates with high
probability (photometrically selected)
list.dat 82 25 List of fits images
fits/* . 25 Individual fits images
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Note on tablea4.dat: This catalogue contains sources without radial velocity
measurements in the literature.
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 9 F9.6 deg RAdeg Right ascension (J2000)
11- 20 F10.6 deg DEdeg Declination (J2000)
22- 26 F5.2 mag umag Sloan u magnitude (AB)
28- 32 F5.3 mag e_umag rms uncertainty on umag
34- 38 F5.2 mag gmag Sloan g magnitude (AB)
40- 44 F5.3 mag e_gmag rms uncertainty on gmag
46- 50 F5.2 mag rmag Sloan r magnitude (AB)
52- 56 F5.3 mag e_rmag rms uncertainty on rmag
58- 62 F5.2 mag imag Sloan i magnitude (AB)
64- 68 F5.3 mag e_imag rms uncertainty on imag
70- 74 F5.2 mag Jmag J magnitude (AB)
76- 80 F5.3 mag e_Jmag rms uncertainty on Jmag
82- 86 F5.2 mag Ksmag Ks magnitude (AB)
88- 92 F5.3 mag e_Ksmag rms uncertainty on Ksmag
94- 98 F5.1 pc rh ?=- Measured half-light (effective) radius
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Byte-by-byte Description of file: tablea2.dat tablea3.dat tablea4.dat
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Bytes Format Units Label Explanations
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1- 9 F9.6 deg RAdeg Right ascension (J2000)
11- 20 F10.6 deg DEdeg Declination (J2000)
22- 26 F5.2 mag umag Sloan u magnitude (AB)
28- 33 F6.3 mag e_umag rms uncertainty on umag
35- 39 F5.2 mag gmag Sloan g magnitude (AB)
41- 45 F5.3 mag e_gmag rms uncertainty on gmag
47- 51 F5.2 mag rmag Sloan r magnitude (AB)
53- 57 F5.3 mag e_rmag rms uncertainty on rmag
59- 63 F5.2 mag imag Sloan i magnitude (AB)
65- 69 F5.3 mag e_imag rms uncertainty on imag
71- 75 F5.2 mag Jmag J magnitude (AB)
77- 82 F6.3 mag e_Jmag rms uncertainty on Jmag
84- 88 F5.2 mag Ksmag Ks magnitude (AB)
90- 96 F7.3 mag e_Ksmag rms uncertainty on Ksmag
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Byte-by-byte Description of file: tablea5.dat tablea6.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- ID Name (UCD-CAND-NNN for tablea5,
FDS-UCD-NN for tablea6)
14- 22 F9.6 deg RAdeg Right ascension (J2000)
24- 33 F10.6 deg DEdeg Declination (J2000)
35- 39 F5.2 mag umag Sloan u magnitude (AB)
41- 45 F5.3 mag e_umag rms uncertainty on umag
47- 51 F5.2 mag gmag Sloan g magnitude (AB)
53- 57 F5.3 mag e_gmag rms uncertainty on gmag
59- 63 F5.2 mag rmag Sloan r magnitude (AB)
65- 69 F5.3 mag e_rmag rms uncertainty on rmag
71- 75 F5.2 mag imag Sloan i magnitude (AB)
77- 81 F5.3 mag e_imag rms uncertainty on imag
83- 87 F5.2 mag Jmag J magnitude (AB)
89- 93 F5.3 mag e_Jmag rms uncertainty on Jmag
95- 99 F5.2 mag Ksmag Ks magnitude (AB)
101-105 F5.3 mag e_Ksmag rms uncertainty on Ksmag
107-110 F4.1 pc rh ?=- Measured half-light (effective) radius
112-113 I2 --- Comp The position of the object in u-i/i-Ks diagram
in respect to the completeness contours
115-116 I2 --- Star The likelihood of the object to be in the
foregound (star)
118-120 I3 --- UCD The likelihood of the object to be a UCD or GC
122-123 I2 --- Gal The likelihood of the object to be in the
background (galaxy, farther than the Fornax
cluster)
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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- 30 I5 --- Nx Number of pixels along X-axis
32- 36 I5 --- Ny Number of pixels along Y-axis
38- 43 I6 Kibyte size Size of FITS file
45- 56 A12 --- FileName Name of FITS file, in subdirectory fits
58- 82 A25 --- Title Title of the FITS file
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Acknowledgements:
Teymur Saifollahi, teymur.saif(at)gmail.com
(End) Patricia Vannier [CDS] 28-Dec-2021