S.Okamura (Tokyo)
Title:Discovery of Primeval Large-Scale Structures with Forming Clusters at Redshift z=5.7
Abstract:Our group discovered primeval large-scale structures (LSSs) including two proto-clusters in a forming phase at z = 5.7. I will report the discovery in this talk. We carried out extensive deep narrow-band imaging in the 1 deg^2 sky of the Subaru/XMM-Newton Deep Field, and obtained a cosmic map of 515 Lyman alpha emitters (LAEs) in a volume with a transverse dimension of 180 Mpc x 180 Mpc and a depth of about 40 Mpc in comoving units. This cosmic map shows filamentary LSSs, including clusters and 10-40 Mpc scale voids, similar to the present-day LSSs. This indicates that LSSs had been developed well by z=6. Our spectroscopic follow-up observations identified overdense regions in which two dense clumps of LAEs with a sphere of 1-Mpc diameter in physical units are included. These clumps show about 130 times higher star-formation activities than the mean field. These clumps would be clusters in a formation phase involving a burst of galaxy formation. The standard hierarchical scenario may be consistent with the discovered primeval LSSs, but not with the forming clusters where galaxy formation is so highly enhanced.
J. Carlstrom (Chicago)
Title: Sunyaev-Zel'dovich effect observations: Status and future plans
Abustruct:
K. Grainge (Cambridgs)
Title: Current status of the AMI project
abstract: AMI is a dual array interferometer designed to survey for galaxy clusters through SZ observations at 12-18 GHz. It will comprise an array of ten 3.7m dishes in a compact configuration (baselines out to 20m) and an upgrade to the Ryle telescope of eight 12.8m dishes (baselines out to 120m). Commissoning observations are currently underway on a subset of the compact array antennas and science observations are expected to start by October 2005. The Lords Bridge site before the New Year to give access to north-south baselines. Work is now allow subtraction of confusing radio sources; this will be necessary for all but the shallowest of cluster surveys.
L. Lamagna (Rome)
Title:The SZ effect as a cosmic thermometer
Abstract: The potential of the SZ effect as a probe is not only bound to the well known SZ/X-Ray combination to measure distances on the cosmological ladder, but also to the possibility of testing the basic hypotheses of modern cosmology, including the isotropy of the universe and the standard scaling law of the CMB temperature with redshift. I will discuss the potential capabilities of this method and the pioneering approach to the combined Coma and A2163 SZ datasets, with particular attention to the systematics and their dependence on the X-Ray measurements of the observed clusters. I will also outline the main characteristics of the recently approved GEMINI-SZ porject, devoted to the observation of a large sample of galaxy clusters in the mm/submm region with a combined set of ground-based and balloon-borne facilities.
C. Li (Taipei)
Title: The AMiBA project
Abstract: The Array for Microwave Background Anisotropy is a 7-element interferometer to be sited on Mauna Loa, Hawaii. The seven 60-cm telescopes are mounted on a 6-meter platform, and operate at 3mm wavelength. At this time, the site construction work is going to be finished, and the installation of the telescope mount will follow. The receiver, correlator, and LO-IF packages were shipped to Hilo for integration and testing before being installed on the platform. The array is expected to start opeartion in March 2005.
S. Nozawa (Josai)
Title: Relativistic corrections to the Sunyaev-Zeldovich effect for clusters of galaxies
abstract: @We review the formalism of the relativistic corrections to the Sunyaev-Zeldovich (SZ) Effect for Clusters of Galaxies. We study the thermal and kinematical SZ effects, the polarization effect, the double scattering effect. We also extend the formalism to the observer's system moving with a velocity with respect to the CMB frame. We also present the analytic fitting formuae which are applicable to the high-temperature galaxy clusters.
H. Ezawa (NAOJ)
Title:Progress of the Sunyaev-Zel'dovich effect observations in Japan
Abstract:Observational study of the Sunyaev-Zel'dovich effect through galaxy clusters in Japan has been continuously progressing since the first observation in 1997. Current S-Z observations in Japan are focused on single dish measurements with the 45 m telescope in Nobeyama Radio Observatory. The multi-beam receiver at 40 GHz or the bolometer array at 150 GHz combined with a single dish large telescope provide us high angular resolution S-Z images with wide field of view, which lead to detailed studies of the complex structure of the ICM, or gave constraints to the cosmological parameters. The history and the results of the Japanese S-Z observations will be summarized in the talk.
L. Knox (UC Davis)
Title: Probing inflation, dark energy, and neutrino masses with SZ and cosmic shear
Abstract: I discuss scientific applications of both cosmic shear and SZ surveys.Measurement of the large-scale matter power spectrum can improve our understanding of inflation and ability to discern the sum of neutrino masses. Distances measured into the dark-matter dominated era, combined with CMB measurements, can be used for precision testing of inflation's prediction of zero mean curvature. Sensitivity to both geometry and the growth of structure can be used to discriminate between dark energy and modified gravity as explanations for the observed acceleration. While lensing observations can contribute to our understanding of mass-SZ observable relations, SZ observations can be used to improve the modeling of the baryonic contribution to cosmic shear.
N. Sugiyama (NAOJ)
Title: Reionization and SZ effect
Abstract: I will review the current status of the reionization of the universe and discuss possible detection of reionization by using CMB, especially kinetic SZ effect.
J. Mohr (Illinois)
Title: Observations of galaxy cluster X-ray scaling relations: effects of cool cores and merging on cluster cosmology
Abstract: Significant progress in understanding the mass variation and redshift evolution of cluster structure has been made using cluster scaling relations. Further progress is required to fully harvest the cosmological information in a large scale cluster survey like that planned with the South Pole Telescope. One goal is to determine the dominant source(s) of scatter in the observed scaling relations and to determine the extent to which these structural variations will limit our ability to study the cosmic acceleration or dark energy. An analysis of a large, local sample of clusters indicates that the cool core phenomenon dominates merger induced structural variations as a source of scatter. If this behavior persists at high redshift, then it is the redshift evolution of the cool core phenomenon rather than changes in merger activity that poses the greatest challenge for X-ray cluster surveys. SZE cluster surveys will be less affected because of the lower sensitivity to cluster core structure. Regardless, cluster survey self-calibration techniques provide the possibility of meeting these challenges in both X-ray and SZE surveys.
N. Ota (RIKEN)
Title: Core structure and thermal evolution of X-ray clusters
Abstract: We present a statistical study of ICM structure based on a large sample of ROSAT and ASCA distant clusters. We have found from the beta-model analysis that the sample shows high concentrations around two typical core sizes of rc~50 kpc and ~200 kpc. As rc is correlated with other observational parameters (central electron density and cooling timescale etc.), it is expected to be a key parameter to understand the density structure and thermal evolution of ICM. We then investigated the parameter correlations against rc and cooling time including their connections to the Lx-T relation to find some interesting trends. We will show the results and discuss the observational implications on the gas evolution.
T. Furusho (ISAS/JAXA)
Title: High resolution X-ray spectroscopy with Astro-E2 XRS: Status and prospects
Abstract: The X-ray Spectrometer (XRS) is a non-dispersive X-ray detector on board the Japan-US collaborative X-ray Astronomy observatory, Astro-E2, which is scheduled for launch early in the summer of 2005. The XRS achieves a high energy resolution of 6.0 eV at 6 keV (FWHM) over 0.3-12 keV bandpass. I present the instrument design and the performance based on our ground calibration tests. I also show examples of simulated XRS spectra and expected scientific results of some galaxy clusters which are planned to be observed in the first six months after the launch.
T. Tamura (ISAS/JAXA)
Title: XMM-Newton observations of central regions of galaxy clusters
abstract: We present some results from X-ray spectroscopic observations with XMM-Newton. Utilizing its large telescopes along with two types of instruments (CCD and reflection-grating), XMM observation have revealed new and detailed properties of X-ray clusters. We analyzed some 20 bright clusters data systematically to measure thermal and chemical structures, mainly around cluster cores. We found that central regions around the cD galaxy is not so cooled compared to the isobaric cooling-flow model. This suggests some unknown heating and/or mixing process have important role on the thermal nature of the core of clusters. In addition, we discuss elemental abundances in the ICM and their origins.
Y. Fujita (NAOJ)
Title: The cooling flow problem and the tsunami model
Abstract: Clusters of Galaxies are filled with hot X-ray gas (intracluster medium). Since the gas density is high in the central regions, the radiative cooling time of the gas is much smaller than the age of the universe. Thus, without heating sources, the gas at the cluster centers should cool and gas-flows toward the centers should be established to compensate the lowered pressure (a cooling flow model). However, recent X-ray observations have shown that the gas is not cooling as much as the cooling flow model predicted. This means that there are some unknown heating sources. I would like to review this paradigm shift and introduce the 'tsunami model' as a possible solution of the problem.
Y. Fukazawa (Hiroshima)
Title: Scaling relation of X-ray properties from elliptical galaxies to rich clusters
Abstract: Utilizing ASCA archival data of about 300 objects of elliptical galaxies, groups, and clusters of galaxies, we performed systematic measurements of the X-ray properties of hot gas in their systems. In the luminosity--temperature (LT) relation, we find two breaks at around ICM temperatures of 1 keV and 4 keV, and such breaks are also evident in the gas mass vs temperature relation. We found that the ICM mass within the scaling radius $R_{1500}$ follows the relation of $M_{\rm gas}\propto T^{2.33\pm0.07}$ from X-ray faint galaxies to rich clusters. Therefore, we speculate that even such X-ray faint systems contain a large-scale hot gas, which is too faint to detect. Recent Chandra data allow us to measure the mass profile in elliptical galaxies, and we found that no systematic difference between galaxy groups and X-ray faint elliptical galaxies. We will give some implications, based on both ASCA and Chandra results.
T. Ohashi (Tokyo Metropolitan)
Title: Future Japanese X-ray missions and the prospect of cluster studies
Abstract: Recent X-ray results on clusters of galaxies reveal that the clusters are dynamically evolving. We show that high-resolution spectroscopy of clusters is a powerful method to explore the process of cluster evolution in view of gas dynamics and chemical enrichment. Following Astro-E2, the Japanese X-ray group we plan a large X-ray mission NeXT, which features multi-layer coated hard X-ray mirrors and a wide-field microcalorimeters. The first hard X-ray image up to 80 keV and a fine energy spectrum with about 2 eV resolution will be obtained from a number of objects. We will describe the mission capabilities and expected science on clusters of galaxies.
N. Yoshida (Nagoya)
Title: The temperature structure of the IGM/ICM and the cluster SZ effect
Abstract: I present the results from a recent large hydrodynamical simulation of structure formation. The simulation explicitly accounts for the relaxatioon process between electrons and ions. I discuss implications for WHIM detection and the cluster SZ effect.
N. Yamasaki (ISAS/JAXA)
Title: X-ray observability of WHIM and our new mission concept DIOS
abstract: In present universe, 30-50% of total baryons is supposed to be hot/warm intergalactic medium (WHIM) tracing the large-scale strycture. Recent X-ray observation result to detect emissions from or absorption features due to WHM are reviewed. In order to carry out a homogeneous survey by the oxygen emission lines from WHIM, we are proposing a soft X-ray small mission DIOS (Diffuse Intergalactic Oxygen Surveyor).