Low-ionization galaxies and evolution in a pilot survey up to<i>z</i>= 1

Giraud, E.; Gu, Qing; Melnick, J.; Quintana, H.; Selman, F.; Toledo, I.; Zelaya, P.

doi:10.1088/1674-4527/11/3/001

Cited by 5 publications

(5 citation statements)

References 62 publications

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“…A detailed description of the data sets used in the present investigation has been presented in three previous papers: Giraud et al and Toledo et al (, henceforth Paper I), to which we refer for comprehensive discussions of the observing and data analysis methodologies. It is useful to reproduce here the relevant figures from Paper I to set the data in the present context, in particular because, as described above, observationally it is extremely difficult, if not impossible, to separate the ICL from the extended haloes of the BCG.…”

Section: The Datamentioning

confidence: 99%

Intergalactic stellar populations in intermediate redshift clusters

Melnick

Giraud

Toledo

et al. 2012

Monthly Notices of the Royal Astronomical Society

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A substantial fraction of the total stellar mass in rich clusters of galaxies resides in a diffuse intergalactic component usually referred to as the Intra-Cluster Light (ICL). Theoretical models indicate that these intergalactic stars originate mostly from the tidal interaction of the cluster galaxies during the assembly history of the cluster, and that a significant fraction of these stars could have formed in-situ from the late infall of cold metal-poor gas clouds onto the cluster. The models make predictions about the age distribution of the ICL stars, which may provide additional observational constraints. However, these models also over-predict the fraction of stellar mass in the ICL by a substantial margin. Here we present population synthesis models for the ICL of a dumb-bell dominated intermediate redshift (z=0.29) X-ray cluster for which we have deep MOS data obtained with the FORS2 instrument. In a previous paper we have proposed that the dumbell galaxy act as a grinding machine tearing to pieces the galaxies that pass nearby thus enriching the intergalactic medium. In this paper we analyze the spectra at different locations within the ICL and find that it is dominated by old metal rich stars, at odds with what has been found in nearby clusters where the stars that dominate the ICL are old and metal poor. While we see a weak evidence of a young, metal poor, component, if real, these young stars would amount to less than 1% of the total ICL mass, much less than the up to 30% predicted by the models. We propose that the very metal rich (i.e. 2.5 times solar) stars in the ICL of our cluster, which comprise approximately 40% of the total mass, originate mostly from the central dumb-bell galaxy, while the remaining solar and metal poor stars come from spiral, post-starburst (E+A), and metal poor dwarf galaxies. About 16% of the ICL stars are old and metal poor.Comment: 10 pages, 6 figure

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Section: The Datamentioning

confidence: 99%

Intergalactic stellar populations in intermediate redshift clusters

Melnick

Giraud

Toledo

et al. 2012

Monthly Notices of the Royal Astronomical Society

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“…The analysis of the field population around the cluster is presented in two separate papers (Giraud et al 2011a, hereafter Paper I; Giraud et al 2011b) that also contain the details of the observations and the data analysis procedures. The present paper is devoted to the investigation of the diffuse ICL component and the analysis of the dynamics of the cluster based on our deep images and deep spectroscopy.…”

Section: Introductionmentioning

confidence: 99%

Diffuse intracluster light at intermediate redshifts: intracluster light observations in an X-ray cluster at z= 0.29★

Toledo

Melnick

Selman

et al. 2011

Monthly Notices of the Royal Astronomical Society

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The diffuse intracluster light (ICL) contains a significant fraction of the total stellar mass in clusters of galaxies, and contributes in roughly equal proportion as the hot intracluster medium to the total baryon content of clusters. Because of the potential importance of understanding the origin of the ICL in the context of the formation and evolution of structure in the Universe, the field has recently undergone a revival both in the quality and quantity of observational and theoretical investigations. Because of cosmological dimming, the observational work has mostly concentrated on low‐redshift clusters, but clearly observations at higher redshifts can provide interesting clues about the evolution of the diffuse component. In this paper we present the first results of a programme to characterize the ICL of intermediate‐redshift clusters. We find that at z∼ 0.3, the X‐ray cluster RX J0054.0−2823 already has a significant ICL and that the fraction of the total light in the ICL and the brightest cluster galaxy (BCG) is comparable to that of similar clusters at lower redshift. We also find that the kinematics of the ICL is consistent with it being the remnant of tidally destroyed galaxies streaming in the central regions of the cluster, which has three central giant elliptical galaxies acting as an efficient ‘galaxy grinding machine’. Our cluster has a bi‐modal radial velocity distribution and thus two possible values for the velocity dispersion. We find that the cluster fits well in the correlation between BCG+ICL fraction and cluster mass for a range of velocity dispersions, leading us to question the validity of a relevant correlation between these two quantities.

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“…Our observations, data, analysis (spectral extraction, flux calibrations, methods, quantitative analysis of stellar populations) are described in details in [8], and the main results summarized in the present poster, can be found in [9].…”

Section: Resultsmentioning

confidence: 99%

Galaxy evolution as it appears at z < 1

Giraud¹,

Gu²,

Melnick³

et al. 2011

Proceedings of Identification of Dark Matter 2010 — PoS(IDM2010)

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We study spectral evolution of galaxies in a magnitude limited sample in a pencil beam of 10' x 7.5' from z = 1 down to 0.3. We bin our individual galaxy spectra to obtain representative high S/N spectra based upon large apparent cosmological structures. We divide the resulting average spectra in three groups: galaxies with pure absorption line spectra, galaxies with emission lines and blue continua, and galaxies with emission lines and red continua. We further divide emissionline galaxies in star-forming galaxies, Seyferts, and LINERs by using emission-line ratios and derive stellar fractions from population synthesis models. We estimate the downsizing in emission-line galaxies between z = 0.9 and z = 0.45 in our pencilbeam and the archeological dowsizing in a cluster at z = 0.29, and find the following results: (1) strong star formation in emission line galaxies, (2) aging in emission line galaxies, (3) aging in absorption systems, are shifting from bright to faint systems as cosmological time increases. Each redshift bin is repopulated in new starbursts. Therefore at redshifts z <1 galaxy formation is downsizing both in luminosity and number density. Cold Dark Matter (CDM) models are hierarchical in the sense that large halos are built from the merging of small halos. Our observations indicate that at z < 1 star formation and halo assemblage are no more in phase. Several analysis have shown that there is still a large gap between CDM simulations and observable parameters, and explored various solutions: the abundance of haloes of various masses forming at a given time is very broad, the gravitational sequence of halo formation may be modified by the galaxy formation physics which may change the efficiency of galaxy formation, simulations that incorporate a shutdown seem to be able to reproduce downsizing trends, gravitational shifts in halo formation time are enhanced by the inclusion of AGN feedback. All these attempts however point out a weakness in the CDM halo hypothesis: its low predictive power. It is as if dark matter is closer to baryons than CDM is.

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Low-ionization galaxies and evolution in a pilot survey up toz= 1

Cited by 5 publications

References 62 publications

Intergalactic stellar populations in intermediate redshift clusters

Intergalactic stellar populations in intermediate redshift clusters

Diffuse intracluster light at intermediate redshifts: intracluster light observations in an X-ray cluster at z= 0.29★

Galaxy evolution as it appears at z < 1

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