scholarly journals Estimates for the impact of ultraviolet background fluctuations on galaxy clustering measurements

2019 ◽  
Vol 485 (4) ◽  
pp. 5059-5072 ◽  
Author(s):  
Phoebe Upton Sanderbeck ◽  
Vid Iršič ◽  
Matthew McQuinn ◽  
Avery Meiksin

ABSTRACT Spatial fluctuations in ultraviolet backgrounds can subtly modulate the distribution of extragalactic sources, a potential signal and systematic for large-scale structure surveys. While this modulation has been shown to be significant for 3D Ly α forest surveys, its relevance for other large-scale structure probes has been hardly explored, despite being the only astrophysical process that likely can affect clustering measurements on the scales of ≳Mpc. We estimate that the background fluctuations, modulating the amount of H i, have a fractional effect of (0.03–0.3) × (k/[10−2 Mpc−1])−1 on the power spectrum of 21 cm intensity maps at z = 1–3. We find a smaller effect for H α and Ly α intensity mapping surveys of (0.001–0.1) × (k/[10−2 Mpc−1])−1 and even smaller effect for more traditional surveys that correlate the positions of individual H α or Ly α emitters. We also estimate the effect of backgrounds on low-redshift galaxy surveys in general based on a simple model in which background fluctuations modulate the rate halo gas cools, modulating star formation: We estimate a maximum fractional effect on the power of ∼0.01 (k/[10−2 Mpc−1])−1 at z = 1. We compare sizes of these imprints to cosmological parameter benchmarks for the next generation of redshift surveys: We find that ionizing backgrounds could result in a bias on the squeezed triangle non-Gaussianity parameter fNL that can be larger than unity for power spectrum measurements with a SPHEREx-like galaxy survey, and typical values of intensity bias. Marginalizing over a shape of the form k−1PL, where PL is the linear matter power spectrum, removes much of this bias at the cost of ${\approx } 40{{\ \rm per\ cent}}$ larger statistical errors.

Author(s):  
Marta B. Silva ◽  
Ely D. Kovetz ◽  
Garrett K. Keating ◽  
Azadeh Moradinezhad Dizgah ◽  
Matthieu Bethermin ◽  
...  

AbstractThis paper outlines the science case for line-intensity mapping with a space-borne instrument targeting the sub-millimeter (microwaves) to the far-infrared (FIR) wavelength range. Our goal is to observe and characterize the large-scale structure in the Universe from present times to the high redshift Epoch of Reionization. This is essential to constrain the cosmology of our Universe and form a better understanding of various mechanisms that drive galaxy formation and evolution. The proposed frequency range would make it possible to probe important metal cooling lines such as [CII] up to very high redshift as well as a large number of rotational lines of the CO molecule. These can be used to trace molecular gas and dust evolution and constrain the buildup in both the cosmic star formation rate density and the cosmic infrared background (CIB). Moreover, surveys at the highest frequencies will detect FIR lines which are used as diagnostics of galaxies and AGN. Tomography of these lines over a wide redshift range will enable invaluable measurements of the cosmic expansion history at epochs inaccessible to other methods, competitive constraints on the parameters of the standard model of cosmology, and numerous tests of dark matter, dark energy, modified gravity and inflation. To reach these goals, large-scale structure must be mapped over a wide range in frequency to trace its time evolution and the surveyed area needs to be very large to beat cosmic variance. Only a space-borne mission can properly meet these requirements.


2021 ◽  
Vol 126 (1) ◽  
Author(s):  
Elena Massara ◽  
Francisco Villaescusa-Navarro ◽  
Shirley Ho ◽  
Neal Dalal ◽  
David N. Spergel

2021 ◽  
Vol 2021 (12) ◽  
pp. 003
Author(s):  
José Fonseca ◽  
Chris Clarkson

Abstract In this paper, we study how to directly measure the effect of peculiar velocities in the observed angular power spectra. We do this by constructing a new anti-symmetric estimator of Large Scale Structure using different dark matter tracers. We show that the Doppler term is the major component of our estimator and we show that we can measure it with a signal-to-noise ratio up to ∼ 50 using a futuristic SKAO HI galaxy survey. We demonstrate the utility of this estimator by using it to provide constraints on the Euler equation.


2020 ◽  
Vol 499 (2) ◽  
pp. 1769-1787
Author(s):  
Anaëlle Halle ◽  
Takahiro Nishimichi ◽  
Atsushi Taruya ◽  
Stéphane Colombi ◽  
Francis Bernardeau

ABSTRACT The power spectrum response function of the large-scale structure of the Universe describes how the evolved power spectrum is modified by a small change in initial power through non-linear mode coupling of gravitational evolution. It was previously found that the response function for the coupling from small to large scales is strongly suppressed in amplitude, especially at late times, compared to predictions from perturbation theory (PT) based on the single-stream approximation. One obvious explanation for this is that PT fails to describe the dynamics beyond shell crossing. We test this idea by comparing measurements in N-body simulations to prescriptions based on PT but augmented with adaptive smoothing to account for the formation of non-linear structures of various sizes in the multistream regime. We first start with one-dimensional (1D) cosmology, where the Zel’dovich approximation provides the exact solution in the single-stream regime. Similarly to the three-dimensional (3D) case, the response function of the large-scale modes exhibits a strong suppression in amplitude at small scales that cannot be explained by the Zel’dovich solution alone. However, by performing adaptive smoothing of initial conditions to identify haloes of different sizes and solving approximately post-collapse dynamics in the three-stream regime, agreement between theory and simulations drastically improves. We extend our analyses to the 3D case using the pinocchio algorithm, in which similar adaptive smoothing is implemented on the Lagrangian PT fields to identify haloes and is combined with a spherical halo prescription to account for post-collapse dynamics. Again, a suppression is found in the coupling between small- and large-scale modes and the agreement with simulations is improved.


2001 ◽  
Vol 555 (1) ◽  
pp. 68-73 ◽  
Author(s):  
Christopher J. Miller ◽  
Robert C. Nichol ◽  
David J. Batuski

2021 ◽  
Vol 921 (2) ◽  
pp. 108
Author(s):  
Matías Bravo ◽  
Eric Gawiser ◽  
Nelson D. Padilla ◽  
Joseph DeRose ◽  
Risa H. Wechsler

Sign in / Sign up

Export Citation Format

Share Document