17 research outputs found
Abell 1451 and 1RXS J131423.6-251521: a multi-wavelength study of two dynamically perturbed clusters of galaxies
We present results from optical, X-ray and radio observations of two X-ray
bright (L_X ~ 10^{45} erg/s) galaxy clusters. A1451 is at redshift z=0.1989 and
has line-of-sight velocity dispersion sigma_v = 1330 km/s as measured from 57
cluster galaxies. It has regular X-ray emission without signs of substructure,
a Gaussian velocity distribution, lack of a cooling flow region and significant
deviations from the observed scaling laws between luminosity, temperature and
velocity dispersion, indicating a possible merging shock. There is only one
spectroscopically confirmed cluster radio galaxy, which is close to the X-ray
peak. 1RXS J131423.6-251521 has z=0.2474 and sigma_v = 1100 km/s from 37
galaxies. There are two distinct galaxy groups with a projected separation of
\~700 kpc. The velocity histogram is bi-modal with a redshift-space separation
of ~1700 km/s, and the X-ray emission is double peaked. Although there are no
spectroscopically confirmed cluster radio galaxies, we have identified a
plausible relic source candidate.Comment: 16 pages, 12 figures, some in colour; A&A accepte
An ISOCAM survey through gravitationally lensing galaxy clusters. III. New results from mid-infrared observations of th e cluster Abell 2219
The massive cluster of galaxies Abell 2219 (z = 0.228) was observed at 14.3
m with the Infrared Space Observatory and results were published by
Barvainis et al. (1999). These observations have been reanalyzed using a method
specifically designed for the detection of faint sources that had been applied
to other clusters. Five new sources were detected and the resulting cumulative
total of ten sources all have optical counterparts. The mid-infrared sources
are identified with three cluster members, three foreground galaxies, an
Extremely Red Object, a star and two galaxies of unknown redshift. The spectral
energy distributions (SEDs) of the galaxies are fit with models from a
selection, using the program GRASIL. Best-fits are obtained, in general, with
models of galaxies with ongoing star formation. For three cluster members the
infrared luminosities derived from the model SEDs are between ~5.7x10^10 Lsun
and 1.4x10^11 Lsun, corresponding to infrared star formation rates between 10
and 24 Msun yr^-1. The two cluster galaxies that have optical classifications
are in the Butcher-Oemler region of the color-magnitude diagramme. The three
foreground galaxies have infrared luminosities between 1.5x10^10 Lsun and
9.4x10^10 Lsun yielding infrared star formation rates between 3 and 16 Msun
yr^-1. Two of the foreground galaxies are located in two foreground galaxy
enhancements (Boschin et al. 2004). Including Abell 2219, six distant clusters
of galaxies have been mapped with ISOCAM and luminous infrared galaxies (LIRGs)
have been found in three of them. The presence of LIRGs in Abell 2219
strengthens the association between luminous infrared galaxies in clusters and
recent or ongoing cluster merger activity.Comment: 8 pages, 4 figures, A&A accepted, full paper with high-resolution
figures available at http://bermuda.ucd.ie/~dcoia/papers/. Reference adde
Probing the Universe with Weak Lensing
Gravitational lenses can provide crucial information on the geometry of the
Universe, on the cosmological scenario of formation of its structures as well
as on the history of its components with look-back time. In this review, I
focus on the most recent results obtained during the last five years from the
analysis of the weak lensing regime. The interest of weak lensing as a probe of
dark matter and the for study of the coupling between light and mass on scales
of clusters of galaxies, large scale structures and galaxies is discussed
first. Then I present the impact of weak lensing for the study of distant
galaxies and of the population of lensed sources as function of redshift.
Finally, I discuss the potential interest of weak lensing to constrain the
cosmological parameters, either from pure geometrical effects observed in
peculiar lenses, or from the coupling of weak lensing with the CMB.Comment: To appear Annual Review of Astronomy and Astrophysiscs Vol. 37. Latex
and psfig.sty. Version without figure, 54 pages, 73Kb. Complete version
including 13 figures (60 pages) available on ftp.iap.fr anonymous account in
/pub/from_users/mellier/AnnualReview ; file ARAAmellier.ps.gz 1.6 M
ISO's Contribution to the Study of Clusters of Galaxies
Starting with nearby galaxy clusters like Virgo and Coma, and continuing out
to the furthest galaxy clusters for which ISO results have yet been published
(), we discuss the development of knowledge of the infrared and
associated physical properties of galaxy clusters from early IRAS observations,
through the "ISO-era" to the present, in order to explore the status of ISO's
contribution to this field. Relevant IRAS and ISO programmes are reviewed,
addressing both the cluster galaxies and the still-very-limited evidence for an
infrared-emitting intra-cluster medium. ISO made important advances in
knowledge of both nearby and distant galaxy clusters, such as the discovery of
a major cold dust component in Virgo and Coma cluster galaxies, the elaboration
of the correlation between dust emission and Hubble-type, and the detection of
numerous Luminous Infrared Galaxies (LIRGs) in several distant clusters. These
and consequent achievements are underlined and described. We recall that, due
to observing time constraints, ISO's coverage of higher-redshift galaxy
clusters to the depths required to detect and study statistically significant
samples of cluster galaxies over a range of morphological types could not be
comprehensive and systematic, and such systematic coverage of distant clusters
will be an important achievement of the Spitzer Observatory.Comment: 22 pages, 7 figures. Accepted for publication in Space Science
Reviews ISO Special Issue "ISO science legacy - a compact review of ISO major
achievements", Ed.C.Cesarky & A.Salama Updated 23 Aug. 2005 in order to
change some citations from astro-ph nos. to full Journal references after
they were publishe
An ISOCAM survey through gravitationally lensing galaxy clusters III : new results from mid-infrared observations of the cluster Abell 2219
The massive cluster of galaxies Abell 2219 (z = 0.228) with two spectacular gravitational lensing arcs was observed at 14.3 μm (hereafter 15 μm) with the Infrared Space Observatory and results were published by Barvainis et al. (\cite{1999AJ....118..645B}). These observations have been reanalysed using a method specifically designed for the detection of faint sources that had been applied to other clusters. Five new sources were detected and the resulting cumulative total of ten sources all have optical counterparts. The mid-infrared sources are identified with three cluster members, three foreground galaxies, an Extremely Red Object, a star and two galaxies of unknown redshift. The spectral energy distributions (SEDs) of the galaxies are fit with models from a selection, using the program GRASIL. Best-fits are obtained, in general, with models of galaxies with ongoing star formation. Infrared luminosities and star formation rates are obtained for six sources: the cluster members and the foreground galaxies. For the three cluster members the infrared luminosities derived from the model SEDs are between ˜5.7 × 1010 L⊙ and 1.4 × 1011 L⊙, corresponding to infrared star formation rates between 10 and 24 M⊙ yr-1. The two cluster galaxies that have optical classifications are in the Butcher-Oemler region of the color-magnitude diagramme. The three foreground galaxies have infrared luminosities between 1.5 × 1010 L⊙ and 9.4 × 1010 L⊙ yielding infrared star formation rates between 3 and 16 M⊙ yr-1. Two of the foreground galaxies are located in two foreground galaxy enhancements (Boschin et al. \cite{2004A&A...416..839B}). Including Abell 2219, six distant clusters of galaxies have been mapped with ISOCAM and luminous infrared galaxies (LIRGs) have been found in three of them. The presence of LIRGs in Abell 2219 strengthens the association between luminous infrared galaxies in clusters and recent or ongoing cluster merger activity. Based on observations with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, the Netherlands and the UK) and with the participation of ISAS and NASA