15 research outputs found
The Subaru FMOS galaxy redshift survey (FastSound). V. Intrinsic alignments of emission line galaxies at
Intrinsic alignments (IA), the coherent alignment of intrinsic galaxy
orientations, can be a source of a systematic error of weak lensing surveys.
The redshift evolution of IA also contains information about the physics of
galaxy formation and evolution. This paper presents the first measurement of IA
at high redshift, , using the spectroscopic catalog of blue
star-forming galaxies of the FastSound redshift survey, with the galaxy shape
information from the Canada-Hawaii-France telescope lensing survey. The IA
signal is consistent with zero with power-law amplitudes fitted to the
projected correlation functions for density-shape and shape-shape correlation
components, and ,
respectively. These results are consistent with those obtained from blue
galaxies at lower redshifts (e.g., and
at from the WiggleZ survey). The
upper limit of the constrained IA amplitude corresponds to a few percent
contamination to the weak-lensing shear power spectrum, resulting in systematic
uncertainties on the cosmological parameter estimations by and .Comment: 11pages, 7 figures, 1 table, accepted for publication in PAS
On the Systematic Errors of Cosmological-Scale Gravity Tests using Redshift Space Distortion: Non-linear Effects and the Halo Bias
Redshift space distortion (RSD) observed in galaxy redshift surveys is a
powerful tool to test gravity theories on cosmological scales, but the
systematic uncertainties must carefully be examined for future surveys with
large statistics. Here we employ various analytic models of RSD and estimate
the systematic errors on measurements of the structure growth-rate parameter,
, induced by non-linear effects and the halo bias with respect to
the dark matter distribution, by using halo catalogues from 40 realisations of
comoving Mpc cosmological N-body simulations. We
consider hypothetical redshift surveys at redshifts z=0.5, 1.35 and 2, and
different minimum halo mass thresholds in the range of --
. We find that the systematic error of
is greatly reduced to ~5 per cent level, when a recently proposed
analytical formula of RSD that takes into account the higher-order coupling
between the density and velocity fields is adopted, with a scale-dependent
parametric bias model. Dependence of the systematic error on the halo mass, the
redshift, and the maximum wavenumber used in the analysis is discussed. We also
find that the Wilson-Hilferty transformation is useful to improve the accuracy
of likelihood analysis when only a small number of modes are available in power
spectrum measurements.Comment: 10 pages, 8 figures, 1 table, accepted for publication in MNRA
赤方偏移1.4の宇宙論的分光サーベイFastSoundにおけるサーベイデザインの検討 : データ解析手法の開発および赤方偏移カタログの構築
学位の種別: 課程博士審査委員会委員 : (主査)東京大学准教授 嶋作 一大, 東京大学教授 吉井 讓, 東京大学教授 土居 守, 東京大学教授 高田 昌広, 東京大学准教授 大内 正己University of Tokyo(東京大学
The effects of non-linearity on the growth rate constraint from velocity correlation functions
The two-point statistics of the cosmic velocity field, measured from galaxy
peculiar velocity (PV) surveys, can be used as a dynamical probe to constrain
the growth rate of large-scale structures in the universe. Most works use the
statistics on scales down to a few tens of Megaparsecs, while using a
theoretical template based on the linear theory. In addition, while the cosmic
velocity is volume-weighted, the observable line-of-sight velocity two-point
correlation is density-weighted, as sampled by galaxies, and therefore the
density-velocity correlation term also contributes, which has often been
neglected. These effects are fourth order in powers of the linear density
fluctuation , compared to of the linear
velocity correlation function, and have the opposite sign. We present these
terms up to in real space based on the standard perturbation
theory, and investigate the effect of non-linearity and the density-velocity
contribution on the inferred growth rate , using -body
simulations. We find that for a next-generation PV survey of volume , these effects amount to a shift of
by per cent and is comparable to the forecasted
statistical error when the minimum scale used for parameter estimation is
.Comment: 16 pages, 6 figures, submitted to MNRA
A Study of Selection Methods for H alpha Emitting Galaxies at z~1.3 for the Subaru/FMOS Galaxy Redshift Survey for Cosmology (FastSound)
The efficient selection of high-redshift emission galaxies is important for
future large galaxy redshift surveys for cosmology. Here we describe the target
selection methods for the FastSound project, a redshift survey for H alpha
emitting galaxies at z=1.2-1.5 using Subaru/FMOS to measure the linear growth
rate f\sigma 8 via Redshift Space Distortion (RSD) and constrain the theory of
gravity. To select ~400 target galaxies in the 0.2 deg^2 FMOS field-of-view
from photometric data of CFHTLS-Wide (u*g'r'i'z'), we test several different
methods based on color-color diagrams or photometric redshift estimates from
spectral energy distribution (SED) fitting. We also test the improvement in
selection efficiency that can be achieved by adding near-infrared data from the
UKIDSS DXS (J). The success rates of H alpha detection with FMOS averaged over
two observed fields using these methods are 11.3% (color-color, optical), 13.6%
(color-color, optical+NIR), 17.3% (photo-z, optical), and 15.1% (photo-z,
optical+NIR). Selection from photometric redshifts tends to give a better
efficiency than color-based methods, although there is no significant
improvement by adding J band data within the statistical scatter. We also
investigate the main limiting factors for the success rate, by using the sample
of the HiZELS H alpha emitters that were selected by narrow-band imaging.
Although the number density of total H alpha emitters having higher H alpha
fluxes than the FMOS sensitivity is comparable with the FMOS fiber density, the
limited accuracy of photometric redshift and H alpha flux estimations have
comparable effects on the success rate of <~20% obtained from SED fitting.Comment: 12 pages, 7 figures, accepted to PAS
The Subaru FMOS Galaxy Redshift Survey (FastSound). III. The mass-metallicity relation and the fundamental metallicity relation at
We present the results from a large near-infrared spectroscopic survey with
Subaru/FMOS (\textit{FastSound}) consisting of 4,000 galaxies at
with significant H detection. We measure the gas-phase
metallicity from the [N~{\sc ii}]6583/H emission line ratio of
the composite spectra in various stellar mass and star-formation rate bins. The
resulting mass-metallicity relation generally agrees with previous studies
obtained in a similar redshift range to that of our sample. No clear dependence
of the mass-metallicity relation with star-formation rate is found. Our result
at is roughly in agreement with the fundamental metallicity relation
at with fiber aperture corrected star-formation rate. We detect
significant [S~{\sc ii}]6716,6731 emission lines from the
composite spectra. The electron density estimated from the [S~{\sc
ii}]6716,6731 line ratio ranges from 10 -- 500 cm, which
generally agrees with that of local galaxies. On the other hand, the
distribution of our sample on [N~{\sc ii}]6583/H vs. [S~{\sc
ii}]6716,6731/H is different from that found locally.
We estimate the nitrogen-to-oxygen abundance ratio (N/O) from the N2S2 index,
and find that the N/O in galaxies at is significantly higher than
the local values at a fixed metallicity and stellar mass. The metallicity at
recalculated with this N/O enhancement taken into account decreases
by 0.1 -- 0.2 dex. The resulting metallicity is lower than the local
fundamental metallicity relation.Comment: 14 pages, 10 figures, 2 tables, accepted for publication in PAS