NGC 3628-UCD1: A POSSIBLE
                    <i>ω</i>
                    CEN ANALOG EMBEDDED IN A STELLAR STREAM

Jennings, Zachary G.; Romanowsky, Aaron J.; Brodie, Jean P.; Norris, Mark A.; Forbes, Duncan A.; Martínez–Delgado, David; Fagioli, Martina

doi:10.1088/2041-8205/812/1/l10

Cited by 33 publications

(40 citation statements)

References 52 publications

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“…North is up and east is to the left. The zoomed-in square shows the LSB galaxy we found in the image and the blue circle shows the NGC 3628-UCD1 (Jennings et al 2015).…”

Section: Resultsmentioning

confidence: 99%

DGSAT: Dwarf Galaxy Survey with Amateur Telescopes

Javanmardi

Martínez–Delgado

Kroupa³

et al. 2016

A&A

108

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Context. We introduce the Dwarf Galaxy Survey with Amateur Telescopes (DGSAT) project and report the discovery of eleven low surface brightness (LSB) galaxies in the fields of the nearby galaxies NGC 2683, NGC 3628, NGC 4594 (M 104), NGC 4631, NGC 5457 (M 101), and NGC 7814. Aims. The DGSAT project aims to use the potential of small-sized telescopes to probe LSB features around large galaxies and to increase the sample size of the dwarf satellite galaxies in the Local Volume. Methods. Using long exposure images, fields of the target spiral galaxies are explored for extended LSB objects. After identifying dwarf galaxy candidates, their observed properties are extracted by fitting models to their light profiles. Results. We find three, one, three, one, one, and two new LSB galaxies in the fields of NGC 2683, 3628, 4594, 4631, 5457, and 7814, respectively. In addition to the newly found galaxies, we analyse the structural properties of nine already known galaxies. All of these 20 dwarf galaxy candidates have effective surface brightnesses in the range 25.3 < ∼ µ e < ∼ 28.8 mag arcsec −2 and are fit with Sersic profiles with indices n < ∼ 1. Assuming that they are in the vicinity of the above mentioned massive galaxies, their r-band absolute magnitudes, their effective radii, and their luminosities are in the ranges −15.6 < ∼ M r < ∼ −7.8, 160 pc < ∼ R e < ∼ 4.1 kpc, and 0.1 × 10 6 < ∼ L L r < ∼ 127 × 10 6 , respectively. To determine whether these LSB galaxies are indeed satellites of the above mentioned massive galaxies, their distances need to be determined via further observations. Conclusions. Using small telescopes, we are readily able to detect LSB galaxies with similar properties to the known dwarf galaxies of the Local Group.

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“…North is up and east is to the left. The zoomed-in square shows the LSB galaxy we found in the image and the blue circle shows the NGC 3628-UCD1 (Jennings et al 2015).…”

Section: Resultsmentioning

confidence: 99%

DGSAT: Dwarf Galaxy Survey with Amateur Telescopes

Javanmardi

Martínez–Delgado

Kroupa³

et al. 2016

A&A

108

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“…The commonly-observed, two-component nature of a UCD galaxies' structure might reflect the original nuclear star cluster surrounded by the some of the remnants of its former host galaxy (e.g. Evstigneeva et al 2007;Jennings et al 2015;Voggel et al 2016;Wittmann et al 2016). Such objects would still house the original galaxy's supermassive black hole (SMBH), or perhaps intermediate-mass black hole (IMBH: 10 2 < M bh /M < 10 5 ).…”

Section: Introductionmentioning

confidence: 99%

A consistency test for determining whether ultracompact dwarf galaxies could be the remnant nuclei of threshed galaxies

Graham

2019

Monthly Notices of the Royal Astronomical Society

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It has been suggested that ultra-compact dwarf (UCD) galaxies are the "threshed" remains of larger galaxies. Simulations have revealed that extensive tidal-stripping may pare a galaxy back to its tightly-bound, compact nuclear star cluster. It has therefore been proposed that the two-component nature of UCD galaxies may reflect the original nuclear star cluster surrounded by the paltry remnants of its host galaxy. A simple quantitative test of this theory is devised and applied here. If the mass of the central black hole in UCD galaxies, relative to the mass of the UCD galaxies' inner stellar component, i.e. the suspected nuclear star cluster, matches with the (black hole mass)-(nuclear star cluster mass) relation observed in other galaxies, then it would provide quantitative support for the stripped galaxy scenario. Such consistency is found for four of the five UCD galaxies reported to have a massive black hole. This (black hole mass)-(nuclear star cluster mass) relation is then used to predict the central black hole mass in two additional UCD galaxies, and to reveal that NGC 205 and possibly NGC 404 (which only has an upper limit to its black hole mass) also follow this scaling relation.1 While grossly over-represented in some published scaling diagrams, at a given luminosity, just 0.5 percent of dwarf galaxies are "compact elliptical" galaxies (Chilingarian, private communication).

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“…Fortunately, based on significantly increased data samples, in recent years a consensus has begun to emerge that both suggested channels are responsible for forming UCDs (Hilker 2006;Norris & Kannappan 2011;Chiboucas et al 2011;Brodie et al 2011;Norris et al 2014;Forbes et al 2014;Pfeffer et al 2014Pfeffer et al , 2016Voggel et al 2016). This change was motivated by the observation that while the numbers of UCDs are in general in excellent agreement with those expected from an extrapolation of the globular cluster luminosity function (GCLF : Hilker 2006;Norris & Kannappan 2011;Mieske et al 2012), an increasing number of cases of definitively stripped nuclei UCDs do exist (Norris & Kannappan 2011;Seth et al 2014;Norris et al 2015;Jennings et al 2015;Ahn et al 2017Ahn et al , 2018. Furthermore, cosmological simulations indicate that stripped nuclei could make up a significant fraction of the UCD population only at the highest masses (>10 7 M ), and should be a relatively negligible component (< 10%) at the lowest masses (Pfeffer et al 2014).…”

Section: Introductionmentioning

confidence: 99%

Is there a fundamental upper limit to the mass of a star cluster?

Norris

Ven

Kannappan

et al. 2019

Monthly Notices of the Royal Astronomical Society

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The discovery around the turn of the millenium of a population of very massive (M > 2×10 6 M ) compact stellar systems (CSS) with physical properties (radius, velocity dispersion, stellar mass etc.) that are intermediate between those of the classical globular cluster (GC) population and galaxies led to questions about their exact nature. Recently a consensus has emerged that these objects, usually called ultra compact dwarfs (UCDs), are a mass-dependent mixture of high mass star clusters and remnant nuclei of tidally disrupted galaxies. The existence of genuine star clusters with stellar masses >10 7 M naturally leads to questions about the upper mass limit of the star cluster formation process. In this work we compile a comprehensive catalog of compact stellar systems, and reinforce the evidence that the true ancient star cluster population has a maximum mass of M ∼ 5×10 7 M , corresponding to a stellar mass at birth of close to 10 8 M . We then discuss several physical and statistical mechanisms potentially responsible for creating this limiting mass.

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NGC 3628-UCD1: A POSSIBLE ω CEN ANALOG EMBEDDED IN A STELLAR STREAM

Cited by 33 publications

References 52 publications

DGSAT: Dwarf Galaxy Survey with Amateur Telescopes

DGSAT: Dwarf Galaxy Survey with Amateur Telescopes

A consistency test for determining whether ultracompact dwarf galaxies could be the remnant nuclei of threshed galaxies

Is there a fundamental upper limit to the mass of a star cluster?

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