Yasushi Suto

THE LUMINOSITY AND COLOR DEPENDENCE OF THE GALAXY CORRELATION FUNCTION

Westudytheluminosityandcolordependenceofthegalaxytwo-pointcorrelationfunctionintheSloanDigitalSky Survey, starting from a sample of � 200,000 galaxies over 2500 deg 2 . We concentrate our analysis on volume-limited subsamples of specified luminosity ranges, for which we measure the projected correlation function wp(rp), which is directly related to the real-space correlation function � (r). The amplitude of wp(rp) rises continuously with luminosity from Mr �� 17: 5t oMr �� 22:5, with the most rapid increase occurring above the characteristic luminosity L� (Mr �� 20:5). Over the scales 0:1 h � 1 Mpc � 22 can be approximated, imperfectly, by power-law three-dimensional correlation functions � (r) ¼ (r/r0) � � with � � 1:8 and r0(L� ) � 5:0 h � 1 Mpc. The brightest subsample, � 23 < Mr < � 22, has a significantly steeper � (r). When we divide samples by color, redder galaxies exhibit a higher amplitude and steeper correlation function at all luminosities. The correlation amplitude of blue galaxies increases continuously with luminosity, but the luminosity dependence for red galaxies is less regular, with bright red galaxies exhibiting the strongest clustering at large scales and faint red galaxies exhibiting the strongest clustering at small scales. We interpret these results using halo occupation distribution (HOD) models assuming concordance cosmological parameters. For most samples, an HOD model with two adjustable parameters fits the wp(rp) data better than a power law, explaining inflections at rp � 1 3 h � 1 Mpc as the transition between the one-halo and two-halo regimes of � (r). The implied minimum mass for a halo hosting a central galaxy more luminous than L grows steadily, with Mmin / L at low luminosities and a steeper dependence above L� . The mass at which a halo has, on average, one satellite galaxy brighter than L is M1 � 23Mmin(L), at all luminosities. These results imply a conditional luminosity function (at fixed halo mass) in which central galaxies lie far above a Schechter function extrapolation of the satellite population. The HOD model fits nicely explain the color dependence of wp(rp) and the cross correlation between red and blue galaxies. For galaxies with Mr < � 21, halos slightly above Mmin have blue central galaxies, while more massive halos have red central galaxies and predominantly red satellite populations. The fraction of blue central galaxies increases steadily with decreasing luminosity and host halo mass. The strong clustering offaint red galaxies follows from the fact that nearly all of them are satellite systems in high-mass halos. The HOD fitting results are in good qualitative agreement with the predictions of numerical and semianalytic models of galaxy formation. Subject headingg cosmology: observations — cosmology: theory — galaxies: distances and redshifts — galaxies: halos — galaxies: statistics — large-scale structure of universe

The Density Profiles of the Dark Matter Halo Are Not Universal.

We perform a series of high-resolution N-body simulations designed to examine the density profiles of dark matter halos. From 12 simulated halos ranging in mass from 2x1012 to 5x1014 h-1 M middle dot in circle (represented by approximately 1 million particles within the virial radius), we find a clear systematic correlation between the halo mass and the slope of the density profile at 1% of the virial radius, in addition to the variations of the slope among halos of similar mass. More specifically, the slope is approximately -1.5, -1.3, and -1.1 for galaxy-, group-, and cluster-mass halos, respectively. While we confirm the earlier simulation results that the inner slope is steeper than the universal profile originally proposed by Navarro, Frenk, & White, this mass dependence is inconsistent with several analytical arguments attempting to link the inner slope with the primordial index of the fluctuation spectrum. Thus, we conclude that the dark matter density profiles, especially in the inner region, are not universal.

Measurement of Spin-Orbit Alignment in an Extrasolar Planetary System

We determine the stellar, planetary, and orbital properties of the transiting planetary system HD 209458 through a joint analysis of high-precision radial velocities, photometry, and timing of the secondary eclipse. Of primary interest is the strong detection of the Rossiter-McLaughlin effect, the alteration of photospheric line profiles that occurs because the planet occults part of the rotating surface of the star. We develop a new technique for modeling this effect and use it to determine the inclination of the planetary orbit relative to the apparent stellar equator (λ = -4o.4 ± 1o.4), and the line-of-sight rotation speed of the star (v sin /_★ = 4.70 ± 0.16 km s^(-1)). The uncertainty in these quantities has been reduced by an order of magnitude relative to the pioneering measurements by Queloz and collaborators. The small but nonzero misalignment is probably a relic of the planet formation epoch, because the expected timescale for tidal coplanarization is larger than the age of the star. Our determination of v sin /★ is a rare case in which rotational line broadening has been isolated from other broadening mechanisms.

Semianalytical predictions for statistical properties of x-ray clusters of galaxies in cold dark matter universes

Temperature and luminosity functions of X-ray clusters are computed semi-analytically, combining a simple model for the cluster gas properties with the distribution functions of halo formation epochs proposed by Lacey & Cole (1993) and Kitayama & Suto (1996). In contrast to several previous approaches which apply the Press--Schechter mass function in a straightforward manner, our method can explicitly take into account the temperature and luminosity evolution of clusters. In order to make quantitative predictions in a specific cosmological context, we adopt cold dark matter (CDM) universes. Assuming the baryon density parameter

The Rossiter-McLaughlin Effect and Analytic Radial Velocity Curves for Transiting Extrasolar Planetary Systems

\Omega_{\rm B}=0.0125 h^{-2}

X-Ray Gas Density Profile of Clusters of Galaxies from the Universal Dark Matter Halo

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Constraints on the Fluctuation Amplitude and Density Parameter from X-Ray Cluster Number Counts

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Extragalactic science, cosmology, and Galactic archaeology with the Subaru Prime Focus Spectrograph

is the Hubble constant in units of 100 km

The dependence of dark halo clustering on formation epoch and concentration parameter

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A gravitationally lensed quasar with quadruple images separated by 14.62 arcseconds.

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