Single metal-poor ultra compact dwarf galaxy at one kiloparsec distance from the low-mass elliptical galaxy FCC 47

Katja Fahrion; Iskren Georgiev; Michael Hilker; Mariya Lyubenova; Glenn van de Ven; Mayte Alfaro-Cuello; Enrico M. Corsini; Marc Sarzi; Richard M. McDermid; Tim De Zeeuw

doi:10.1051/0004-6361/201834941

Single metal-poor ultra compact dwarf galaxy at one kiloparsec distance from the low-mass elliptical galaxy FCC 47

Katja Fahrion^*, Iskren Georgiev, Michael Hilker, Mariya Lyubenova, Glenn van de Ven, Mayte Alfaro-Cuello, Enrico M. Corsini, Marc Sarzi, Richard M. McDermid, Tim De Zeeuw

^*Corresponding author for this work

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Abstract

Context. Photometric surveys of galaxy clusters have revealed a large number of ultra compact dwarfs (UCDs) around predominantly massive elliptical galaxies. Their origin is still debated as some UCDs are considered to be the remnant nuclei of stripped dwarf galaxies while others seem to mark the high-mass end of the star cluster population.

Aims. We aim to characterize the properties of a UCD found at very close projected distance (r_proj= 1.1 kpc) from the centre of the low-mass (M ∼ 10¹⁰M⊙) early-type galaxy FCC 47. This is a serendipitous discovery from MUSE adaptive optics science verification data. We explore the potential origin of this UCD as either a massive cluster or the remnant nucleus of a dissolved galaxy.

Methods. We used archival Hubble Space Telescope data to study the photometric and structural properties of FCC 47-UCD1. In the MUSE data, the UCD is unresolved, but we used its spectrum to determine the radial velocity and metallicity.

Results. The surface brightness of FCC 47-UCD1 is best described by a single King profile with low concentration C = R_t/R_c∼ 10 and large effective radius (r_eff = 24 pc). Its integrated magnitude and blue colour (M_g= −10.55 mag, (g−z) = 1.46 mag) combined with a metallicity of [M/H] = −1.12 ± 0.10 dex and an age >8 Gyr obtained from the full fitting of the MUSE spectrum suggests a stellar population mass of M_∗= 4.87 × 10⁶M⊙. The low S/N of the MUSE spectrum prevents detailed stellar population analysis. Due to the limited spectral resolution of MUSE, we can only give an upper limit on the velocity dispersion (σ < 17 km s⁻¹), and consequently on its dynamical mass (M_dyn< 1.3 × 10⁷M⊙).

Conclusions. The origin of the UCD cannot be constrained with certainty. The low metallicity, old age, and magnitude are consistent with a star cluster origin, whereas the extended size is consistent with an origin as the stripped nucleus of a dwarf galaxy with a initial stellar mass of a few 10⁸M⊙.

Original language	English
Article number	A50
Number of pages	17
Journal	Astronomy and Astrophysics
Volume	625
DOIs	https://doi.org/10.1051/0004-6361/201834941
Publication status	Published - 8 May 2019

Bibliographical note

Reproduced with permission from Astronomy & Astrophysics, Copyright 2019 ESO. First published in Astronomy and Astrophysics, 625, A50, 2019, published by EDP Sciences. The original publication is available at https://doi.org/10.1051/0004-6361/201834941. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

Keywords

Dynamics
Galaxies: dwarf
Galaxies: individual: NGC 1336
Galaxies: kinematics
Galaxies: nuclei

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10.1051/0004-6361/201834941

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Cite this

@article{6d71b18f1b1f488e8db16f7c54c322b1,

title = "Single metal-poor ultra compact dwarf galaxy at one kiloparsec distance from the low-mass elliptical galaxy FCC 47",

abstract = "Context. Photometric surveys of galaxy clusters have revealed a large number of ultra compact dwarfs (UCDs) around predominantly massive elliptical galaxies. Their origin is still debated as some UCDs are considered to be the remnant nuclei of stripped dwarf galaxies while others seem to mark the high-mass end of the star cluster population.Aims. We aim to characterize the properties of a UCD found at very close projected distance (rproj= 1.1 kpc) from the centre of the low-mass (M ∼ 1010 M⊙) early-type galaxy FCC 47. This is a serendipitous discovery from MUSE adaptive optics science verification data. We explore the potential origin of this UCD as either a massive cluster or the remnant nucleus of a dissolved galaxy.Methods. We used archival Hubble Space Telescope data to study the photometric and structural properties of FCC 47-UCD1. In the MUSE data, the UCD is unresolved, but we used its spectrum to determine the radial velocity and metallicity.Results. The surface brightness of FCC 47-UCD1 is best described by a single King profile with low concentration C = Rt/Rc∼ 10 and large effective radius (reff = 24 pc). Its integrated magnitude and blue colour (Mg= −10.55 mag, (g−z) = 1.46 mag) combined with a metallicity of [M/H] = −1.12 ± 0.10 dex and an age >8 Gyr obtained from the full fitting of the MUSE spectrum suggests a stellar population mass of M∗= 4.87 × 106 M⊙. The low S/N of the MUSE spectrum prevents detailed stellar population analysis. Due to the limited spectral resolution of MUSE, we can only give an upper limit on the velocity dispersion (σ < 17 km s−1), and consequently on its dynamical mass (Mdyn< 1.3 × 107 M⊙). Conclusions. The origin of the UCD cannot be constrained with certainty. The low metallicity, old age, and magnitude are consistent with a star cluster origin, whereas the extended size is consistent with an origin as the stripped nucleus of a dwarf galaxy with a initial stellar mass of a few 108 M⊙.",

keywords = "Dynamics, Galaxies: dwarf, Galaxies: individual: NGC 1336, Galaxies: kinematics, Galaxies: nuclei",

author = "Katja Fahrion and Iskren Georgiev and Michael Hilker and Mariya Lyubenova and {van de Ven}, Glenn and Mayte Alfaro-Cuello and Corsini, {Enrico M.} and Marc Sarzi and McDermid, {Richard M.} and {De Zeeuw}, Tim",

note = "Reproduced with permission from Astronomy & Astrophysics, Copyright 2019 ESO. First published in Astronomy and Astrophysics, 625, A50, 2019, published by EDP Sciences. The original publication is available at https://doi.org/10.1051/0004-6361/201834941. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.",

year = "2019",

month = may,

day = "8",

doi = "10.1051/0004-6361/201834941",

language = "English",

volume = "625",

journal = "Astronomy and Astrophysics",

issn = "0004-6361",

publisher = "EDP Sciences",

}

TY - JOUR

T1 - Single metal-poor ultra compact dwarf galaxy at one kiloparsec distance from the low-mass elliptical galaxy FCC 47

AU - Fahrion, Katja

AU - Georgiev, Iskren

AU - Hilker, Michael

AU - Lyubenova, Mariya

AU - van de Ven, Glenn

AU - Alfaro-Cuello, Mayte

AU - Corsini, Enrico M.

AU - Sarzi, Marc

AU - McDermid, Richard M.

AU - De Zeeuw, Tim

N1 - Reproduced with permission from Astronomy & Astrophysics, Copyright 2019 ESO. First published in Astronomy and Astrophysics, 625, A50, 2019, published by EDP Sciences. The original publication is available at https://doi.org/10.1051/0004-6361/201834941. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

PY - 2019/5/8

Y1 - 2019/5/8

N2 - Context. Photometric surveys of galaxy clusters have revealed a large number of ultra compact dwarfs (UCDs) around predominantly massive elliptical galaxies. Their origin is still debated as some UCDs are considered to be the remnant nuclei of stripped dwarf galaxies while others seem to mark the high-mass end of the star cluster population.Aims. We aim to characterize the properties of a UCD found at very close projected distance (rproj= 1.1 kpc) from the centre of the low-mass (M ∼ 1010 M⊙) early-type galaxy FCC 47. This is a serendipitous discovery from MUSE adaptive optics science verification data. We explore the potential origin of this UCD as either a massive cluster or the remnant nucleus of a dissolved galaxy.Methods. We used archival Hubble Space Telescope data to study the photometric and structural properties of FCC 47-UCD1. In the MUSE data, the UCD is unresolved, but we used its spectrum to determine the radial velocity and metallicity.Results. The surface brightness of FCC 47-UCD1 is best described by a single King profile with low concentration C = Rt/Rc∼ 10 and large effective radius (reff = 24 pc). Its integrated magnitude and blue colour (Mg= −10.55 mag, (g−z) = 1.46 mag) combined with a metallicity of [M/H] = −1.12 ± 0.10 dex and an age >8 Gyr obtained from the full fitting of the MUSE spectrum suggests a stellar population mass of M∗= 4.87 × 106 M⊙. The low S/N of the MUSE spectrum prevents detailed stellar population analysis. Due to the limited spectral resolution of MUSE, we can only give an upper limit on the velocity dispersion (σ < 17 km s−1), and consequently on its dynamical mass (Mdyn< 1.3 × 107 M⊙). Conclusions. The origin of the UCD cannot be constrained with certainty. The low metallicity, old age, and magnitude are consistent with a star cluster origin, whereas the extended size is consistent with an origin as the stripped nucleus of a dwarf galaxy with a initial stellar mass of a few 108 M⊙.

AB - Context. Photometric surveys of galaxy clusters have revealed a large number of ultra compact dwarfs (UCDs) around predominantly massive elliptical galaxies. Their origin is still debated as some UCDs are considered to be the remnant nuclei of stripped dwarf galaxies while others seem to mark the high-mass end of the star cluster population.Aims. We aim to characterize the properties of a UCD found at very close projected distance (rproj= 1.1 kpc) from the centre of the low-mass (M ∼ 1010 M⊙) early-type galaxy FCC 47. This is a serendipitous discovery from MUSE adaptive optics science verification data. We explore the potential origin of this UCD as either a massive cluster or the remnant nucleus of a dissolved galaxy.Methods. We used archival Hubble Space Telescope data to study the photometric and structural properties of FCC 47-UCD1. In the MUSE data, the UCD is unresolved, but we used its spectrum to determine the radial velocity and metallicity.Results. The surface brightness of FCC 47-UCD1 is best described by a single King profile with low concentration C = Rt/Rc∼ 10 and large effective radius (reff = 24 pc). Its integrated magnitude and blue colour (Mg= −10.55 mag, (g−z) = 1.46 mag) combined with a metallicity of [M/H] = −1.12 ± 0.10 dex and an age >8 Gyr obtained from the full fitting of the MUSE spectrum suggests a stellar population mass of M∗= 4.87 × 106 M⊙. The low S/N of the MUSE spectrum prevents detailed stellar population analysis. Due to the limited spectral resolution of MUSE, we can only give an upper limit on the velocity dispersion (σ < 17 km s−1), and consequently on its dynamical mass (Mdyn< 1.3 × 107 M⊙). Conclusions. The origin of the UCD cannot be constrained with certainty. The low metallicity, old age, and magnitude are consistent with a star cluster origin, whereas the extended size is consistent with an origin as the stripped nucleus of a dwarf galaxy with a initial stellar mass of a few 108 M⊙.

KW - Dynamics

KW - Galaxies: dwarf

KW - Galaxies: individual: NGC 1336

KW - Galaxies: kinematics

KW - Galaxies: nuclei

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JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

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Single metal-poor ultra compact dwarf galaxy at one kiloparsec distance from the low-mass elliptical galaxy FCC 47

Abstract

Bibliographical note

Keywords

Access to Document

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Cosmic origins: How do galaxies build chemical complexity over cosmic time?

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Single metal-poor ultra compact dwarf galaxy at one kiloparsec distance from the low-mass elliptical galaxy FCC 47

Abstract

Bibliographical note

Keywords

Access to Document

Other files and links

Fingerprint

Projects

Cosmic origins: How do galaxies build chemical complexity over cosmic time?

Cite this