scholarly journals UV SEDs of early-type cluster galaxies: a new look at the UV upturn

2018 ◽  
Vol 476 (1) ◽  
pp. 1010-1020 ◽  
Author(s):  
S S Ali ◽  
M N Bremer ◽  
S Phillipps ◽  
R De Propris
Keyword(s):  
Early Type ◽  
Cluster Galaxies ◽  
Uv Upturn ◽  
New Look

scholarly journals The GALEX Ultraviolet Virgo Cluster Survey (GUViCS)

2018 ◽  
Vol 611 ◽  
pp. A42 ◽  
Author(s):  
S. Boissier ◽  
O. Cucciati ◽  
A. Boselli ◽  
S. Mei ◽  
L. Ferrarese
Keyword(s):  
Virgo Cluster ◽  
Small Error ◽  
Early Type ◽  
Redshift Range ◽  
Cluster Galaxies ◽  
The Past ◽  
Brightest Cluster Galaxies ◽  
Binary Channel ◽  
Using Data ◽  
Uv Upturn

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.

scholarly journals Environmental effects on the UV upturn in local clusters of galaxies

2019 ◽  
Vol 487 (3) ◽  
pp. 3021-3028 ◽  
Author(s):  
Sadman S Ali ◽  
Malcolm N Bremer ◽  
Steven Phillipps ◽  
Roberto De Propris
Keyword(s):  
Early Type ◽  
Cluster Galaxies ◽  
Cluster Environment ◽  
On Line ◽  
Cluster Properties ◽  
Projected Position ◽  
Far Ultraviolet ◽  
Uv Upturn ◽  
Intrinsic Feature ◽  
Infrared Data

ABSTRACT We explore the dependence of ultraviolet (UV) upturn colours in early-type cluster galaxies on the properties of their parent clusters (such as velocity dispersion and X-ray luminosity) and on the positions and kinematics of galaxies within them. We use a sample of 24 nearby clusters with highly complete spectroscopy and optical/infrared data to select a suitable sample of red-sequence galaxies, whose far-ultraviolet and NUV magnitudes we measure from archival GALEX data. Our results show that the UV upturn colour has no dependence on cluster properties and has the same range in all clusters. There is also no dependence on the projected position within clusters or on line-of-sight velocity. Therefore, our conclusion is that the UV upturn phenomenon is an intrinsic feature of cluster early-type galaxies, irrespective of their cluster environment.

scholarly journals Evolution of the UV upturn in cluster galaxies: Abell 1689

2018 ◽  
Vol 478 (1) ◽  
pp. 541-547 ◽  
Author(s):  
S S Ali ◽  
M N Bremer ◽  
S Phillipps ◽  
R De Propris
Keyword(s):  
Cluster Galaxies ◽  
Uv Upturn

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

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.

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

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.

scholarly journals Stellar population study in early-type galaxies: an approach from the K band

2009 ◽  
Vol 5 (S262) ◽  
pp. 85-88
Author(s):  
Esther Mármol-Queraltó ◽  
Nicolás Cardiel ◽  
P. Sánchez-Blázquez ◽  
S. C. Trager ◽  
R. F. Peletier ◽  
...  
Keyword(s):  
Stellar Population ◽  
Near Infrared ◽  
Optical Measurements ◽  
Early Type ◽  
Spectral Window ◽  
Cluster Galaxies ◽  
Medium Resolution ◽  
Fornax Cluster ◽  
New Generation ◽  
K Band

AbstractA full understanding of the physical properties of integrated stellar systems demands a multiwavelength approach since each spectral window shows us the contribution of different types of stars. However, most of the observational effort in stellar population studies has been focused on the optical range. Now, the new generation of instruments allow us to explore the K band, where RGB and AGB stars dominate the light of the integrated spectra. Here we present a K-band spectroscopic analysis of early-type galaxies in different environments. Our sample comprises 12 field early-type galaxies observed with ISAAC at VLT with medium resolution, and they are compared with 11 Fornax cluster galaxies previously reported by Silva et al. (2008). The clear differences found in the infrared DCO and NaI indices between field and Fornax galaxies are discussed, trying to solve the puzzle formed by the near-infrared and optical measurements.

scholarly journals Stellar population gradients in early-type cluster galaxies with VIMOS IFU★

2008 ◽  
Vol 389 (4) ◽  
pp. 1891-1904 ◽  
Author(s):  
T. D. Rawle ◽  
Russell J. Smith ◽  
J. R. Lucey ◽  
A. M. Swinbank
Keyword(s):  
Stellar Population ◽  
Early Type ◽  
Cluster Galaxies

scholarly journals Star formation in bulges from GALEX

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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