The M31 globular cluster system:<i>ugriz</i>and<i>K</i>-band photometry and structural parameters

We present a catalog of 908 objects observed with the Large Sky Area MultiObject Fiber Spectroscopic Telescope (LAMOST) in the vicinity fields of M31 and M33, targeted as globular clusters (GCs) and candidates. The targets include known GCs and candidates selected from the literature, as well as new candidates selected from the Sloan Digital Sky Survey (SDSS). Analysis shows that 356 of them are likely GCs of various degree of confidence, while the remaining ones turn out to be background galaxies and quasars, stars and H II regions in M31 or foreground Galactic stars. The 356 likely GCs include 298 bona fide GCs and 26 candidates known in the literature. Three candidates selected from the Revised Bologna Catalog of M31 GCs and candidates (RBC) and one possible cluster from Johnson et al. are confirmed to be bona fide clusters. We search for new GCs in the halo of the M31 amongst the new candidates selected from the SDSS photometry. Based on radial velocities yielded by LAMSOT spectra and visual examination of the SDSS images, we find 28 objects, 5 bona fide and 23 likely GCs. Amongst the five bona fide GCs, three have been recently discovered independently by others, the remaining 25 are our new identifications, including two bona fide ones. The new identified objects fall at projected distances ranging from 13 to 265 kpc from M31. Of the two newly discovered bona fide GCs, one is located near M33, probably a GC belonging to M33. The other bona fide GC falls on the Giant Stream with a projected distance of 78 kpc from M31. Of the 23 newly identified likely GCs, one has a projected distance of about 265 kpc from M31 and could be an intergalactic cluster.

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“…2. The GC sample of Peacock et al (2010) is used to help create the following GC selection criteria.…”

Section: New Candidates Selected From the Sdss Photometrymentioning

confidence: 99%

The LAMOST spectroscopic survey of globular clusters in M31 and M33. I. catalog and new identifications

Chen

Liu

Xiang

et al. 2015

Res. Astron. Astrophys.

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“…However, the integrated emission of these clusters can be accurately measured with relatively short exposures (compared with cluster systems around more distant galaxies). In this paper, we consider all globular clusters listed as "class 1" in the catalog of Peacock et al (2010). 4 These clusters have non-stellar surface brightness profiles and are confirmed to be at the distance of M31 based on spectroscopy or high-resolution Hubble Space Telescope (HST) observations.…”

Section: M31 Globular Cluster Datamentioning

confidence: 99%

“…This sample also excludes the recently identified population of young clusters in M31. Young clusters are classified as those clusters having colors bluer than the old Milky Way globular clusters (Fusi Pecci et al 2005;Peacock et al 2010) or based on spectroscopy of the clusters (Caldwell et al 2009). The catalog includes 416 class 1 clusters, located across the galaxy.…”

Section: M31 Globular Cluster Datamentioning

confidence: 99%

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TESTING STELLAR POPULATION SYNTHESIS MODELS WITH SLOAN DIGITAL SKY SURVEY COLORS OF M31's GLOBULAR CLUSTERS

Peacock¹,

Zepf²,

Maccarone³

et al. 2011

ApJ

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Accurate stellar population synthesis models are vital in understanding the properties and formation histories of galaxies. In order to calibrate and test the reliability of these models, they are often compared with observations of star clusters. However, relatively little work has compared these models in the ugriz filters, despite the recent widespread use of this filter set. In this paper, we compare the integrated colors of globular clusters in the Sloan Digital Sky Survey (SDSS) with those predicted from commonly used simple stellar population (SSP) models. The colors are based on SDSS observations of M31's clusters and provide the largest population of star clusters with accurate photometry available from the survey. As such, it is a unique sample with which to compare SSP models with SDSS observations. From this work, we identify a significant offset between the SSP models and the clusters' g − r colors, with the models predicting colors which are too red by g − r ∼ 0.1. This finding is consistent with previous observations of luminous red galaxies in the SDSS, which show a similar discrepancy. The identification of this offset in globular clusters suggests that it is very unlikely to be due to a minority population of young stars.The recently updated SSP model of Maraston & Strömbäck better represents the observed g − r colors. This model is based on the empirical MILES stellar library, rather than theoretical libraries, suggesting an explanation for the g − r discrepancy.

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“…All observational data for GCs was compiled using catalogs from the following references: Georgiev et al (2009a,b); Forbes & Bridges (2010); ; Strader et al (2011); Galleti et al (2004); Peacock et al (2010); Harris (1996Harris ( ) (2010 Edition. In addition, this work made use of catalogs from Ochsenbein et al (2000).…”

mentioning

confidence: 99%

Clues on the missing sources of reionization from self-consistent modelling of Milky Way and dwarf galaxy globular clusters

Katz¹,

Ricotti²

2014

Monthly Notices of the Royal Astronomical Society

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Globular clusters are unique tracers of ancient star formation. We determine the formation efficiencies of globular clusters across cosmic time by modeling the formation and dynamical evolution of the globular cluster population of a Milky Way type galaxy in hierarchical cosmology, using the merger tree from the Via Lactea II simulation. All of the models are constrained to reproduce the observed specific frequency and initial mass function of globular clusters in isolated dwarfs. Globular cluster orbits are then computed in a time varying gravitational potential after they are either accreted from a satellite halo or formed in situ, within the Milky Way halo.We find that the Galactocentric distances and metallicity distribution of globular clusters are very sensitive to the formation efficiencies of globular clusters as a function of redshift and halo mass. Our most accurate models reveal two distinct peaks in the globular cluster formation efficiency at z ∼ 2 and z ∼ 7 − 12 and prefer a formation efficiency that is mildly increasing with decreasing halo mass, the opposite of what expected for feedback-regulated star formation. This model accurately reproduces the positions, velocities, mass function, metallicity distribution, and age distribution of globular clusters in the Milky Way and predicts that ∼ 40% formed in situ, within the Milky Way halo, while the other ∼ 60% were accreted from about 20 satellite dwarf galaxies with v cir > 30 km/s, and about 29% or all globular clusters formed at redshifts z > 7.These results further strengthen the notion that globular cluster formation was an important mode of star formation in high-redshift galaxies and likely played a significant role in the reionization of the intergalactic medium.

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The M31 globular cluster system:ugrizandK-band photometry and structural parameters

Cited by 105 publications

References 73 publications

The LAMOST spectroscopic survey of globular clusters in M31 and M33. I. catalog and new identifications

The LAMOST spectroscopic survey of globular clusters in M31 and M33. I. catalog and new identifications

TESTING STELLAR POPULATION SYNTHESIS MODELS WITH SLOAN DIGITAL SKY SURVEY COLORS OF M31's GLOBULAR CLUSTERS

Clues on the missing sources of reionization from self-consistent modelling of Milky Way and dwarf galaxy globular clusters

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