The GALEX Ultraviolet Virgo Cluster Survey (GUViCS)

Context. At low redshift, early-type galaxies often exhibit a rising flux with decreasing wavelength in the 1000–2500 Å range, called “UV upturn”. The origin of this phenomenon is debated, and its evolution with redshift is poorly constrained. The observed GALEX FUV-NUV color can be used to probe the UV upturn approximately to redshift 0.5.Aim. We provide constraints on the existence of the UV upturn up to redshift ~0.4 in the brightest cluster galaxies (BCG) located behind the Virgo cluster, using data from the GUViCS survey.Methods. We estimate the GALEX far-UV (FUV) and near-UV (NUV) observed magnitudes for BCGs from the maxBCG catalog in the GUViCS fields. We increase the number of nonlocal galaxies identified as BCGs with GALEX photometry from a few tens of galaxies to 166 (64 when restricting this sample to relatively small error bars). We also estimate a central color within a 20 arcsec aperture. By using the r-band luminosity from the maxBCG catalog, we can separate blue FUV-NUV due to recent star formation and candidate upturn cases. We use Lick indices to verify their similarity to redshift 0 upturn cases.Results. We clearly detect a population of blue FUV-NUV BCGs in the redshift range 0.10–0.35, vastly improving the existing constraints at these epochs by increasing the number of galaxies studied, and by exploring a redshift range with no previous data (beyond 0.2), spanning one more Gyr in the past. These galaxies bring new constraints that can help distinguish between assumptions concerning the stellar populations causing the UV upturn phenomenon. The existence of a large number of UV upturns around redshift 0.25 favors the existence of a binary channel among the sources proposed in the literature.

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An environmental dependence of the physical and structural properties in the Hydra cluster galaxies

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3326 ◽

2020 ◽

Vol 500 (1) ◽

pp. 1323-1339

Author(s):

Ciria Lima-Dias ◽

Antonela Monachesi ◽

Sergio Torres-Flores ◽

Arianna Cortesi ◽

Daniel Hernández-Lang ◽

...

Keyword(s):

Structural Properties ◽

Clustering Algorithm ◽

Spatial Clustering ◽

Broad Band ◽

Visible Region ◽

Early Type ◽

Cluster Galaxies ◽

Using Data ◽

Stellar Masses ◽

Environmental Dependence

ABSTRACT The nearby Hydra cluster (∼50 Mpc) is an ideal laboratory to understand, in detail, the influence of the environment on the morphology and quenching of galaxies in dense environments. We study the Hydra cluster galaxies in the inner regions (1R200) of the cluster using data from the Southern Photometric Local Universe Survey, which uses 12 narrow and broad-band filters in the visible region of the spectrum. We analyse structural (Sérsic index, effective radius) and physical (colours, stellar masses, and star formation rates) properties. Based on this analysis, we find that ∼88 per cent of the Hydra cluster galaxies are quenched. Using the Dressler–Schectman test approach, we also find that the cluster shows possible substructures. Our analysis of the phase-space diagram together with density-based spatial clustering algorithm indicates that Hydra shows an additional substructure that appears to be in front of the cluster centre, which is still falling into it. Our results, thus, suggest that the Hydra cluster might not be relaxed. We analyse the median Sérsic index as a function of wavelength and find that for red [(u − r) ≥2.3] and early-type galaxies it displays a slight increase towards redder filters (13 and 18 per cent, for red and early type, respectively), whereas for blue + green [(u − r)<2.3] galaxies it remains constant. Late-type galaxies show a small decrease of the median Sérsic index towards redder filters. Also, the Sérsic index of galaxies, and thus their structural properties, do not significantly vary as a function of clustercentric distance and density within the cluster; and this is the case regardless of the filter.

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Spatial distribution of neutral hydrogen in Virgo cluster galaxies of early type

The Astrophysical Journal ◽

10.1086/182218 ◽

1976 ◽

Vol 208 ◽

pp. L7 ◽

Cited By ~ 10

Author(s):

N. Krumm ◽

E. E. Salpeter

Keyword(s):

Spatial Distribution ◽

Neutral Hydrogen ◽

Virgo Cluster ◽

Early Type ◽

Cluster Galaxies

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The range of UV upturn strengths in early-type galaxies can be caused by dissolved metal-rich Globular Clusters

Proceedings of the International Astronomical Union ◽

10.1017/s1743921319007725 ◽

2019 ◽

Vol 14 (S351) ◽

pp. 112-116

Author(s):

Paul Goudfrooij

Keyword(s):

Globular Clusters ◽

Dynamical Evolution ◽

Virgo Cluster ◽

Host Galaxy ◽

Early Type ◽

Luminosity Functions ◽

Central Regions ◽

Specific Frequency ◽

Uv Upturn

AbstractI summarize the scenario by Goudfrooij (2018) in which the bulk of the ultraviolet (UV) upturn of giant early-type galaxies (ETGs) is due to helium-rich stellar populations that formed in massive metal-rich globular clusters (GCs) and subsequently dissolved in the strong tidal field in the central regions of the massive host galaxy. These massive GCs are assumed to show UV upturns similar to those observed recently in M87, the central galaxy in the Virgo cluster of galaxies. Data taken from the literature reveals a strong correlation between the strength of the UV upturn and the specific frequency of metal-rich GCs in ETGs. Adopting a Schechter function parametrization of GC mass functions, simulations of long-term dynamical evolution of GC systems show that this correlation can be explained by variations in the characteristic truncation mass Mc such that Mc increases with ETG luminosity in a way that is consistent with observed GC luminosity functions in ETGs. These findings suggest that the nature of the UV upturn in ETGs and the variation of its strength among ETGs are causally related to that of helium-rich populations in massive GCs, rather than intrinsic properties of field stars in ETGs.

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Globular Clusters, Dwarf Galaxies, and the Assembly of the M87 Halo

Proceedings of the International Astronomical Union ◽

10.1017/s1743921315009837 ◽

2015 ◽

Vol 11 (S317) ◽

pp. 153-158

Author(s):

Eric W. Peng ◽

Hong-Xin Zhang ◽

Chengze Liu ◽

Yiqing Liu

Keyword(s):

Globular Clusters ◽

Dwarf Galaxies ◽

Galaxy Cluster ◽

Virgo Cluster ◽

Early Type ◽

Massive Galaxies ◽

Low Mass ◽

Using Data ◽

The Relationship ◽

Negative Gradient

AbstractAt the center of the nearest galaxy cluster, the Virgo cluster, lies the massive cD galaxy, M87 (NGC 4486). Using data from the Next Generation Virgo Cluster Survey, we investigate the relationship between M87, its globular clusters (GCs), and satellite dwarf galaxies. We find that the kinematics of GCs and ultra-compact dwarfs (UCDs) are different, indicating that UCDs are not simply massive GCs. We also identify a morphological sequence of envelope fraction around UCDs correlated with cluster-centric distance that suggest UCDs are the result of tidal stripping. Lastly, we find that the [α/Fe] abundance ratios of low-mass early-type galaxies in Virgo exhibit a strong negative gradient within ~ 400 kpc of M87, where the galaxies closest to M87 have the highest values. These satellite galaxies are likely the surviving counterparts of accreted dwarfs that contribute stars to the metal-poor, α-rich stellar halos of massive galaxies. Together, these results describe a dense environment that has had a strong and continuing impact on the evolution of its low-mass neighbors.

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Star formation in bulges from GALEX

Proceedings of the International Astronomical Union ◽

10.1017/s174392130801819x ◽

2007 ◽

Vol 3 (S245) ◽

pp. 385-390

Author(s):

Sukyoung K. Yi

Keyword(s):

Star Formation ◽

Young Stars ◽

Star Formation History ◽

Early Type ◽

Limited Sample ◽

Cluster Galaxies ◽

Brightest Cluster Galaxies ◽

Formation History ◽

Formation And Evolution ◽

Bulge Formation

AbstractEarly-type galaxies, considered as large bulges, have been found to have had a much-more-than-boring star formation history in recent years by the UV satellite GALEX. The most massive bulges, brightest cluster galaxies, appear to be relatively free of young stars. But smaller bulges, normal ellipticals and lenticulars, often show unambiguous sign of recent star formation in their UV flux. The fraction of such UV-bright bulges in the volume-limited sample climbs up to the staggering 30%. The bulges of spirals follow similar trends but a larger fraction showing signs of current and recent star formation. The implication on the bulge formation and evolution is discussed.

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The UV-upturn in brightest cluster galaxies

Proceedings of the International Astronomical Union ◽

10.1017/s1743921314004888 ◽

2012 ◽

Vol 10 (H16) ◽

pp. 127-127

Author(s):

S. I. Loubser ◽

P. Sánchez-Blázquez

Keyword(s):

Stellar Population ◽

Control Sample ◽

Mass Range ◽

High Signal ◽

Signal To Noise ◽

Cluster Galaxies ◽

Colour Measurements ◽

Brightest Cluster Galaxies ◽

Sedimentation Model ◽

Uv Upturn

AbstractThis study is part of a series devoted to the investigation of a large sample of brightest cluster galaxies (BCGs), their properties and the relationships between these and the properties of the host clusters. In this paper, we compare the stellar population properties derived from high signal-to-noise, optical long-slit spectra with the GALEX ultraviolet (UV) colour measurements for 36 nearby BCGs to understand the diversity in the most rapidly evolving feature in old stellar systems, the UV-upturn. We investigate: (1) the possible differences between the UV-upturn of BCGs and those of a control sample of ordinary ellipticals in the same mass range, as well as possible correlations between the UV-upturn and other general properties of the galaxies; (2) possible correlations between the UV-upturn and the properties of the host clusters; (3) recently proposed scenarios where helium-sedimentation in the cluster centre can produce an enhanced UV-upturn. We find systematic differences between the UV-colours of BCGs and ordinary ellipticals, but we do not find correlations between these colours and the properties of the host clusters. Furthermore, the observations do not support the predictions made by the helium-sedimentation model as an enhancer of the UV-upturn.

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Evolution in the structural properties of early-type brightest cluster galaxies at small lookback time and dependence on the environment

Monthly Notices of the Royal Astronomical Society ◽

10.1111/j.1365-2966.2009.14601.x ◽

2009 ◽

Vol 395 (3) ◽

pp. 1491-1506 ◽

Cited By ~ 70

Author(s):

Mariangela Bernardi

Keyword(s):

Structural Properties ◽

Early Type ◽

Cluster Galaxies ◽

Brightest Cluster Galaxies

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Real & Simulated IFU Observations of Low-Mass Early-Type Galaxies: Environmental Influence Probed for Cluster Galaxies

Proceedings of the International Astronomical Union ◽

10.1017/s1743921316011364 ◽

2016 ◽

Vol 11 (S321) ◽

pp. 289-289

Author(s):

Agnieszka Sybilska ◽

Ewa Luiza Łokas ◽

Sylvain Fouquet

Keyword(s):

Large Scale ◽

Stellar Population ◽

Environmental Influence ◽

A Priori ◽

Virgo Cluster ◽

Early Type ◽

Complex Issue ◽

Cluster Galaxies ◽

Theoretical Predictions ◽

Low Mass

AbstractWe combine high-quality IFU data with a new set of numerical simulations to study low-mass early type galaxies (dEs) in dense environments. Our earlier study of dEs in the Virgo cluster has produced the first large-scale maps of kinematic and stellar population properties of dEs in those environments (Ryś et al. 2013, 2014, 2015). A quantitative discrimination between various (trans)formation processes proposed for these objects is, however, a complex issue, requiring a priori assumptions about the progenitors of galaxies we observe and study today. To bridge this gap between observations and theoretical predictions, we use the expertise gained in the IFU data analysis to look “through the eye of SAURON” at our new suite of high-resolution N-body simulations of dEs in the Virgo cluster. Mimicking the observers perspective as closely as possible, we can also indicate the existing instrumental and viewer limitations regarding what we are/are not able to detect as observers.

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