2,441 research outputs found
Constraint on the solar using 4,000 days of short baseline reactor neutrino data
There is a well known 2 tension in the measurements of the solar
between KamLAND and SNO/Super-KamioKANDE. Precise determination of
the solar is especially important in connection with current and
future long baseline CP violation measurements. Reference \cite{Seo:2018rrb}
points out that currently running short baseline reactor neutrino experiments,
Daya Bay and RENO, can also constrain solar value as demonstrated
by a GLoBES simulation with a limited systematic uncertainty consideration. In
this work, the publicly available data, from Daya Bay (1,958 days) and RENO
(2,200 days) are used to constrain the solar . Verification of our
method through and measurements is
discussed in Appendix A. Using this verified method, reasonable constraints on
the solar are obtained using above Daya Bay and RENO data, both
individually and combined. We find that the combined data of Daya Bay and RENO
set an upper limit on the solar of 18 eV at
the 95% C.L., including both systematic and statistical uncertainties. This
constraint is slightly more than twice the KamLAND value. As this combined
result is still statistics limited, even though driven by Daya Bay data, the
constraint will improve with the additional running of this experiment.Comment: 8 pages, 6 figures, 2 tables. This paper is a follow up of a Monte
Carlo study reported in arXiv:1808.09150 by two of the authors. The current
paper uses actual data from Daya Bay and RENO that was not previously
available and this is the 1st "combined" result using this new experimental
data. A new figure is added. Some modifications of the tex
Modeling the reconstructed BAO in Fourier space
The density field reconstruction technique, which was developed to partially
reverse the nonlinear degradation of the Baryon Acoustic Oscillation (BAO)
feature in the galaxy redshift surveys, has been successful in substantially
improving the cosmology constraints from recent galaxy surveys such as Baryon
Oscillation Spectroscopic Survey (BOSS). We estimate the efficiency of the
reconstruction method as a function of various reconstruction details. To
directly quantify the BAO information in nonlinear density fields before and
after reconstruction, we calculate the cross-correlations (i.e., propagators)
of the pre(post)-reconstructed density field with the initial linear field
using a mock galaxy sample that is designed to mimic the clustering of the BOSS
CMASS galaxies. The results directly provide the BAO damping as a function of
wavenumber that can be implemented into the Fisher matrix analysis. We focus on
investigating the dependence of the propagator on a choice of smoothing filters
and on two major different conventions of the redshift-space density field
reconstruction that have been used in literature. By estimating the BAO
signal-to-noise for each case, we predict constraints on the angular diameter
distance and Hubble parameter using the Fisher matrix analysis. We thus
determine an optimal Gaussian smoothing filter scale for the signal-to-noise
level of the BOSS CMASS. We also present appropriate BAO fitting models for
different reconstruction methods based on the first and second order Lagrangian
perturbation theory in Fourier space. Using the mock data, we show that the
modified BAO fitting model can substantially improve the accuracy of the BAO
position in the best fits as well as the goodness of the fits.Comment: 21 pages, 7 figures, 1 table. Minor revisions. Matches version
accepted by MNRA
Improved forecasts for the baryon acoustic oscillations and cosmological distance scale
We present the cosmological distance errors achievable using the baryon
acoustic oscillations as a standard ruler. We begin from a Fisher matrix
formalism that is upgraded from Seo & Eisenstein (2003). We isolate the
information from the baryonic peaks by excluding distance information from
other less robust sources. Meanwhile we accommodate the Lagrangian displacement
distribution into the Fisher matrix calculation to reflect the gradual loss of
information in scale and in time due to nonlinear growth, nonlinear bias, and
nonlinear redshift distortions. We then show that we can contract the
multi-dimensional Fisher matrix calculations into a 2-dimensional or even
1-dimensional formalism with physically motivated approximations. We present
the resulting fitting formula for the cosmological distance errors from galaxy
redshift surveys as a function of survey parameters and nonlinearity, which
saves us going through the 12-dimensional Fisher matrix calculations. Finally,
we show excellent agreement between the distance error estimates from the
revised Fisher matrix and the precision on the distance scale recovered from
N-body simulations.Comment: Submitted to ApJ, 21 pages, LaTe
Galaxy Bias and its Effects on the Baryon Acoustic Oscillations Measurements
The baryon acoustic oscillation (BAO) feature in the clustering of matter in
the universe serves as a robust standard ruler and hence can be used to map the
expansion history of the universe. We use high force resolution simulations to
analyze the effects of galaxy bias on the measurements of the BAO signal. We
apply a variety of Halo Occupation Distributions (HODs) and produce biased mass
tracers to mimic different galaxy populations. We investigate whether galaxy
bias changes the non-linear shifts on the acoustic scale relative to the
underlying dark matter distribution presented by Seo et al (2009). For the less
biased HOD models (b < 3), we do not detect any shift in the acoustic scale
relative to the no-bias case, typically 0.10% \pm 0.10%. However, the most
biased HOD models (b > 3) show a shift at moderate significance (0.79% \pm
0.31% for the most extreme case). We test the one-step reconstruction technique
introduced by Eisenstein et al. (2007) in the case of realistic galaxy bias and
shot noise. The reconstruction scheme increases the correlation between the
initial and final (z = 1) density fields achieving an equivalent level of
correlation at nearly twice the wavenumber after reconstruction. Reconstruction
reduces the shifts and errors on the shifts. We find that after reconstruction
the shifts from the galaxy cases and the dark matter case are consistent with
each other and with no shift. The 1-sigma systematic errors on the distance
measurements inferred from our BAO measurements with various HODs after
reconstruction are about 0.07% - 0.15%.Comment: Accepted by ApJ. 21 pages, 10 figure
Probing Dark Energy with Baryonic Acoustic Oscillations from Future Large Galaxy Redshift Surveys
We show that the measurement of the baryonic acoustic oscillations in large
high redshift galaxy surveys offers a precision route to the measurement of
dark energy. The cosmic microwave background provides the scale of the
oscillations as a standard ruler that can be measured in the clustering of
galaxies, thereby yielding the Hubble parameter and angular diameter distance
as a function of redshift. This, in turn, enables one to probe dark energy. We
use a Fisher matrix formalism to study the statistical errors for redshift
surveys up to z=3 and report errors on cosmography while marginalizing over a
large number of cosmological parameters including a time-dependent equation of
state. With redshifts surveys combined with cosmic microwave background
satellite data, we achieve errors of 0.037 on Omega_x, 0.10 on w(z=0.8), and
0.28 on dw(z)/dz for cosmological constant model. Models with less negative
w(z) permit tighter constraints. We test and discuss the dependence of
performance on redshift, survey conditions, and fiducial model. We find results
that are competitive with the performance of future supernovae Ia surveys. We
conclude that redshift surveys offer a promising independent route to the
measurement of dark energy.Comment: submitted to ApJ, 24 pages, LaTe
High-precision predictions for the acoustic scale in the non-linear regime
We measure shifts of the acoustic scale due to nonlinear growth and redshift
distortions to a high precision using a very large volume of
high-force-resolution simulations. We compare results from various sets of
simulations that differ in their force, volume, and mass resolution. We find a
consistency within 1.5-sigma for shift values from different simulations and
derive shift alpha(z) -1 = (0.300\pm 0.015)% [D(z)/D(0)]^{2} using our fiducial
set. We find a strong correlation with a non-unity slope between shifts in real
space and in redshift space and a weak correlation between the initial redshift
and low redshift. Density-field reconstruction not only removes the mean shifts
and reduces errors on the mean, but also tightens the correlations: after
reconstruction, we recover a slope of near unity for the correlation between
the real and redshift space and restore a strong correlation between the low
and the initial redshifts. We derive propagators and mode-coupling terms from
our N-body simulations and compared with Zeldovich approximation and the shifts
measured from the chi^2 fitting, respectively. We interpret the propagator and
the mode-coupling term of a nonlinear density field in the context of an
average and a dispersion of its complex Fourier coefficients relative to those
of the linear density field; from these two terms, we derive a signal-to-noise
ratio of the acoustic peak measurement. We attempt to improve our
reconstruction method by implementing 2LPT and iterative operations: we obtain
little improvement. The Fisher matrix estimates of uncertainty in the acoustic
scale is tested using 5000 (Gpc/h)^3 of cosmological PM simulations from
Takahashi et al. (2009). (abridged)Comment: Revised to match the version in print: a new figure (figure 6) is
added and Section 5 (and figure 8) is revised to include more details. 19
emulated apj pages with 13 figures and 3 table
Passive Evolution of Galaxy Clustering
We present a numerical study of the evolution of galaxy clustering when
galaxies flow passively from high redshift, respecting the continuity equation
throughout. While passive flow is a special case of galaxy evolution, it allows
a well-defined study of galaxy ancestry and serves as an interesting limit to
be compared to non-passive cases. We use dissipationless N-body simulations,
assign galaxies to massive halos at z=1 and z=2 using various HOD models, and
trace these galaxy particles to lower redshift while conserving their number.
We find that passive flow results in an asymptotic convergence at low redshift
in the HOD and in galaxy clustering on scales above ~3Mpc/h for a wide range of
initial HODs. As galaxies become less biased with respect to mass
asymptotically with time, the HOD parameters evolve such that M1/Mm decreases
while alpha converges toward unity, where Mm is the characteristic halo mass to
host a central galaxy, M1 is the halo mass to host one satellite galaxy, and
alpha is the power-law index in the halo-mass dependence of the average number
of satellites per halo. The satellite populations converge toward the Poisson
distribution at low redshift. The convergence is robust for different number
densities and is enhanced when galaxies evolve from higher redshift. We compare
our results with the observed LRG sample from Sloan Digital Sky Survey that has
the same number density. We claim that if LRGs have experienced a strict
passive flow, their should be close to a power law with an index of
unity in halo mass. Discrepancies could be due to dry galaxy merging or new
members arising between the initial and the final redshifts. The spatial
distribution of passively flowing galaxies within halos appears on average more
concentrated than the halo mass profile at low redshift. (abridged)Comment: Accepted for publication in ApJ. 22 emulated apj pages with 15
figures and 4 table
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