scholarly journals UV color-color relation of early-type galaxies

2012 ◽  
Vol 10 (H16) ◽  
pp. 130-130
Author(s):  
Chang H. Ree ◽  
Hyunjin Jeong ◽  
Kyuseok Oh ◽  
Chul Chung ◽  
Joon Hyeop Lee ◽  
...  
Keyword(s):  
Spectral Shape ◽  
Minority Population ◽  
Horizontal Branch ◽  
Early Type ◽  
Spectral Slope ◽  
Canonical Models ◽  
Data Support ◽  
Uv Excess ◽  
Uv Upturn ◽  
Red Sequence

AbstractThe ultraviolet (UV) color-color relation of early-type galaxies (ETGs) in the nearby universe (0.05 < z < 0.12) is re-examined with the latest GALEX GR6 and SDSS DR7 data. By drawing the FUV – NUV (as a measure of UV temperature) versus FUV – r (as a measure of UV amplitude) color-color diagram for the morphologically-cleaned, spectroscopically-cleaned sample of ~3700 quiescent ETGs, we find that the “old and dead“ ETGs consist of a well-defined sequence in UV colors, the “UV red sequence”, so that the stronger UV excess galaxies should have a harder UV spectral shape systematically. However, the observed UV spectral slope is too steep to be reproduced by the canonical models in which the UV flux is mainly controlled by age or metallicity parameters. The observed data support the helium enhancement scenario in which the UV spectral shape of UV upturn (FUV – NUV < 0.9; FUV – r ~ 6) galaxies may be governed by the minority population of helium-enhanced horizontal-branch (HB) stars.

scholarly journals Extreme Horizontal Branch Stars in Passively Evolving Early Type Galaxies

2012 ◽  
Vol 10 (H16) ◽  
pp. 120-120
Author(s):  
Fabiola Hernández-Pérez ◽  
Gustavo Bruzual
Keyword(s):  
Binary Star ◽  
Horizontal Branch ◽  
Population Synthesis ◽  
Early Type ◽  
Star Evolution ◽  
Horizontal Branch Stars ◽  
Uv Excess ◽  
Ehb Stars

AbstractWe study the effects of including binary star evolution in population synthesis models. We use the Hurley et al. (2002) code to compute binary star evolutionary tracks, and follow the procedure by Han et al. (2002), in particular, the two 2HeWD merger channel, to form EHB stars from a binary pair. We apply the resulting models to study UV excess ETGs.

Horizontal-Branch Stars as Sources of the UV Upturn in Early-Type Galaxies

2004 ◽  
Vol 291 (3) ◽  
pp. 223-230 ◽  
Author(s):  
Suk-Jin Yoon ◽  
Young-Wook Lee ◽  
Soo-Chang Rey ◽  
Chang H. Ree ◽  
Sukyoung Ken Yi
Keyword(s):  
Horizontal Branch ◽  
Early Type ◽  
Horizontal Branch Stars ◽  
Uv Upturn

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.

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 The central planetary nebulae populations of external galaxies with SAURON

2011 ◽  
Vol 7 (S283) ◽  
pp. 283-286
Author(s):  
Marc Sarzi
Keyword(s):  
Planetary Nebulae ◽  
Stellar Populations ◽  
Field Observations ◽  
Horizontal Branch ◽  
Early Type ◽  
Luminosity Functions ◽  
External Galaxies ◽  
Nuclear Regions ◽  
Integral Field

AbstractThanks to SAURON integral-field observations we uncovered the planetary nebulae (PNe) populations inhabiting the central and nuclear regions of our galactic neighbours M32 and M31, respectively, and discuss the significant differences between their corresponding PNe luminosity functions in light of the properties of their parent stellar populations. In particular, we conclude that the lack of bright PNe in the nuclear regions of M31 is likely linked to the nearly Solar value for the stellar metallicity, consistent with previous suggestions that a larger metallicity would bias the horizontal-branch (HB) populations toward bluer colors, leading to fewer red HB stars capable of producing PNe and more blue HB stars that instead could contribute to the far-UV flux observed in metal-rich early-type galaxies and, incidentally, in the nucleus of M31.

scholarly journals The SAURON project - XV. Modes of star formation in early-type galaxies and the evolution of the red sequence

2010 ◽  
Vol 402 (4) ◽  
pp. 2140-2186 ◽  
Author(s):  
Kristen L. Shapiro ◽  
Jesús Falcón-Barroso ◽  
Glenn van de Ven ◽  
P. Tim de Zeeuw ◽  
Marc Sarzi ◽  
...  
Keyword(s):  
Star Formation ◽  
Early Type ◽  
Red Sequence

scholarly journals The cosmic epoch dependence of environmental effects on size evolution of red-sequence early-type galaxies

2018 ◽  
Vol 617 ◽  
pp. A53 ◽  
Author(s):  
S. Andreon
Keyword(s):  
Growth Rate ◽  
Galaxy Evolution ◽  
High Redshift ◽  
Early Period ◽  
Early Type ◽  
General Field ◽  
The Galaxy ◽  
Size Growth ◽  
Massive Halos ◽  
Red Sequence

This work aims to observationally investigate the history of size growth of early-type galaxies and how the growth depends on cosmic epoch and the mass of the halo in which they are embedded. We carried out a photometric and structural analysis in the rest-frameVband of a mass-selected (logM/M⊙> 10.7) sample of red-sequence early-type galaxies with spectroscopic/grism redshift in the general field up toz= 2 to complement a previous work presenting an identical analysis but in halos 100 times more massive and 1000 times denser. We homogeneously derived sizes (effective radii) fully accounting for the multi-component nature of galaxies and the common presence of isophote twists and ellipticity gradients. By using these mass-selected samples, composed of 170 red-sequence early-type galaxies in the general field and 224 identically selected and analyzed in clusters, we isolate the effect on galaxy sizes of the halo in which galaxies are embedded and its dependence on epoch. We find that the log of the galaxy size at a fixed stellar mass, logM/M⊙= 11, has increased with epoch at a rate twice as fast in the field than in cluster in the last 10 Gyr (0.26 ± 0.03 versus 0.13 ± 0.02 dex per unit redshift). Red-sequence early-type galaxies in the general field reached the size of their cousins in denser environment byz= 0.25 ± 0.13 in spite of being three times smaller atz∼ 2. Data point toward a model where size growth is epoch-independent (i.e., ∂ logre/∂z=c), but with a ratecdepending on environment, ∂c/∂ logMhalo≈ 0.05. Environment determines the growth rate (d logre/dz) at all redshifts, indicating an external origin for the galaxy growth without any clear epoch where it ceases to have an effect. The larger size of early-type galaxies in massive halos at high redshift indicates that their size grew buildup earlier (atz> 2) at an accelerated rate, slowing down at some still unidentifiedz> 2 redshift. Instead, the size growth rate of red-sequence early-type galaxies in low-mass halos is reversed: it proceeds at an increased rate at late epochs after an early period (z> 2) of reduced growth, in agreement with the qualitative hierarchical picture of galaxy evolution. We found similar values of scatter around the mass-size relation independently of environment and epoch, indicating that the amount of dissipation in the system forming the observed galaxy does not vary greatly with epoch or environment.

scholarly journals Size growth of red-sequence early-type galaxies in clusters in the last 10 Gyr

2016 ◽  
Vol 593 ◽  
pp. A2 ◽  
Author(s):  
S. Andreon ◽  
Hui Dong ◽  
A. Raichoor
Keyword(s):  
Early Type ◽  
Size Growth ◽  
Red Sequence

scholarly journals An optical/near-infrared survey of GCs in early-type galaxies

2009 ◽  
Vol 5 (S266) ◽  
pp. 184-189
Author(s):  
A. L. Chies-Santos ◽  
S. S. Larsen ◽  
E. M. Wehner ◽  
H. Kuntschner ◽  
J. Strader ◽  
...  
Keyword(s):  
Globular Cluster ◽  
Near Infrared ◽  
Horizontal Branch ◽  
Early Type ◽  
Infrared Observations ◽  
Infrared Survey ◽  
Branch Morphology

AbstractOptical/near-infrared observations of 14 globular cluster (GC) systems in early-type galaxies are presented. We investigate the recent claims (Yoon et al. 2006) of colour bimodality in GC systems being an artefact of the nonlinear colour–metallicity transformation driven by horizontal-branch morphology. Taking advantage of the fact that the combination of optical and near-infrared colours can, in principle, break the age/metallicity degeneracy we also analyse age distributions in these systems.

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