Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · 1809.03515

k-cut Cosmic Shear: Tunable Power Spectrum Sensitivity to Test Gravity

Peter L. Taylor·Francis Bernardeau·Thomas D. Kitching
View original source ↗Read source document ↗Export metadata ↓

Abstract

If left unchecked modeling uncertainties at small scales, due to poorly understood baryonic physics and non-linear structure formation, will significantly bias Stage IV cosmic shear two-point statistic parameter constraints. While it is perhaps possible to run N-body or hydrodynamical simulations to determine the impact of these effects this approach is computationally expensive; especially to test a large number of theories of gravity. Instead we propose directly removing sensitivity to small-scale structure from the lensing spectrum, creating a statistic that is robust to these uncertainties. We do this by taking a redshift-dependent l-cut after applying the Bernardeau-Nishimichi-Taruya (BNT) nulling scheme. This reorganizes the information in the lensing spectrum to make the relationship between the angular scale, l, and the structure scale, k, much clearer compared to standard cosmic shear power spectra -- for which no direct relationship exists. We quantify the effectiveness of this method at removing sensitivity to small scales and compute the predicted Fisher error on the dark energy equation of state, w0, for different k-cuts in the matter power spectrum.

Explore related subjects

astro-ph.CO

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Peter L. Taylor, Francis Bernardeau, Thomas D. Kitching. 2018-10-15. k-cut Cosmic Shear: Tunable Power Spectrum Sensitivity to Test Gravity. https://doi.org/10.1103/physrevd.98.083514

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Angular BAO Measurements with the DESI DR1 BGS Sample

We employ a model-independent approach in both the correlation function estimation and the angular BAO feature estimation by computing the angular two-point correlation function. First, we conducted a series of tests to the available DESI tracers to check their representativeness to angular clustering; the result was that, considering the completeness of the first data release across the footprint, we could only make use of the BGS sample for the effective redshifts 0.21 (BGS1) and 0.25 (BGS2). For a reliable analysis in such low redshift, we use the bootstrap of the data itself to construct a covariance matrix that accounts for systematics. We use a purely statistical method to correct the projection effects and find that our results show reasonable agreement with the $θ_{\rm BAO}$ expected by the CPL parameters obtained by DESI DR1, being BGS1 $12.77 \pm 1.15$ degrees and BGS2 $11.70 \pm 1.21$ degrees. This means a tension at the $2.4σ$ ($2.7σ$) level for BGS1 (BGS2) CPL parametrization, while a $2.84σ$ ($3.02σ$) discrepancy within the predicted by $Λ$CDM. We conclude that, with the current sample available, the use of an angular correlation function serving as the BAO probe, although prefers the CPL parametrization, does not provide conclusive results regarding the best cosmological model.

astro-ph.CO↗
arXiv2026

Dispersion Measure Distribution of Unlocalized Fast Radio Bursts as a Probe of the Hubble Constant

We present constraints on the Hubble constant ($H_0$) derived from the observed dispersion measure (DM) distribution of unlocalized fast radio bursts (FRBs). While localized FRBs with redshift measurements have been used to investigate the Hubble tension, their sample remains limited. Here we demonstrate that unlocalized FRBs---which are far more numerous---can independently constrain $H_0$ without requiring redshift information, as cosmic expansion imprints itself on their DM distribution. Analyzing a selected sample of 2124 unlocalized FRBs from the CHIME Catalog II, we obtain $H_0 = 69^{+17}_{-15}~\mathrm{km\,s^{-1}\,Mpc^{-1}}$ at the $1σ$ confidence level, corresponding to an uncertainty of about 22\%. Disentangling the parametric degeneracy among $H_0$, the FRB spectral index $α$, and the characteristic cutoff energy $E_*$ of the FRB energy distribution would reduce the fractional uncertainty in $H_0$ to 9\%. This work constitutes the first $H_0$ measurement derived solely from the DM distribution of unlocalized FRBs, highlighting their potential as a new cosmological probe. Future joint analyses with localized FRBs promise even tighter constraints.

astro-ph.CO↗
arXiv2026

Illuminating the Local Universe: Large-Scale Structure from ZTF Type Ia Supernovae

Within the volume-limited subsample at $z<0.06$ of the Zwicky Transient Facility (ZTF) DR2 sample, we confirm a statistically significant excess of Type Ia supernovae (SNe Ia) around $z \simeq 0.02-0.04$, previously reported but not explained by survey selection effects. Forward simulations assuming a uniform volumetric SN Ia rate and realistic ZTF detection efficiencies fail to reproduce the feature, rejecting this hypothesis at a $12.2σ$ level for the volume-limited sample. We further detect excesses in the rates compared to our survey simulations at $z \simeq 0.08$ and $0.14$, increasing the significance to $14σ$ when extending the redshift range up to $0.12$. To investigate the origin of these inhomogeneities, we compare the observed SN Ia distribution to constrained reconstructions of the local matter density field from the Manticore project, based on Bayesian forward modelling of the 2M++ galaxy catalogue. While SN overdensities are spatially associated with prominent nearby structures such as the Perseus, Coma, and Hercules superclusters, the amplitude of the SN excesses significantly exceeds that expected from local matter overdensities alone. By reconstructing a redshift-dependent volumetric SN Ia rate, we find that local enhancements can reach factors of three to eight within specific clusters, while the sample-averaged rate remains consistent with previous low-redshift measurements. These results indicate that the SN Ia rate is not a linear tracer of the underlying matter density and suggest a strong environmental dependence in dense structures. We discuss possible physical origins and highlight the implications for low-redshift SN cosmology, including correlated peculiar velocities and additional covariance beyond standard linear corrections.

astro-ph.CO↗