Article
Astronomy & Astrophysics
Dipak Munshi, Hayden Lee, Cora Dvorkin, Jason D. McEwen
Summary: This paper introduces two kurt-spectra to study the fourth-order statistics of weak lensing convergence maps. The shapes of these spectra are investigated in relation to source redshifts and smoothing angular scales using numerical simulations. Estimators for beyond fourth-order spectra are provided, and their results are compared with theoretical predictions.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Kazuhiro Kogai, Kazuyuki Akitsu, Fabian Schmidt, Yuko Urakawa
Summary: This study systematically investigates the sensitivity of galaxy shapes to new physics in the initial conditions by decomposing the galaxy shape function into spin components and computing their contributions. It demonstrates that a galaxy imaging survey essentially functions as a spin-sensitive detector of such particles in the early universe, providing valuable insights into the primordial non-Gaussianity generated from higher spin particles.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Giuseppe Fanizza, Enea Di Dio, Ruth Durrer, Giovanni Marozzi
Summary: This paper computes the weak lensing Jacobi map at first order in perturbation theory and demonstrates its gauge invariance and symmetry. It is shown that linear perturbations do not induce any rotation, but vector and tensor perturbations do induce B-modes in the shear. Contrary to previous claims, the shear B-mode power spectrum is not fully determined by the rotation power spectrum, and the E-mode shear power spectrum is not determined by the convergence power spectrum. While this difference is small for scalar perturbations, it becomes significant for tensor perturbations, i.e. gravitational waves.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Alex Krolewski, Simone Ferraro, Martin White
Summary: Recent lensing measurements at low redshifts suggest that the amplitude of lensing in the universe may be lower than predicted by the Lambda CDM model based on Planck CMB data. By analyzing the auto-and cross-correlation signal of unWISE galaxies and Planck CMB lensing maps, cosmological parameters at low redshifts have been inferred, showing tensions with the CMB predictions. The combination of blue, green, and red unWISE samples gives a value of S-8 = 0.784 +/- 0.015, consistent with other low-redshift lensing measurements and in tension with the CMB predictions from Planck.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Sambit K. Giri, Aurel Schneider
Summary: This paper introduces an emulator for baryonic suppression of the matter power spectrum based on a baryonification model with seven free parameters. The emulator can recover the power spectra of hydro-dynamical simulations with sub-percent precision and establish a connection between baryonic suppression, gas, and stellar fractions in haloes. Predictions of deviation from a dark-matter-only power spectrum using measured X-ray gas fractions lead to a constraint on suppression levels at various wave numbers, with a maximum of 20-28% at around k ≈ 7 h/Mpc (68% confidence level).
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Andrina Nicola, Carlos Garcia-Garcia, David Alonso, Jo Dunkley, Pedro G. Ferreira, Anze Slosar, David N. Spergel
Summary: This paper explores the complexities associated with estimating and interpreting shear power spectra, and presents fast and accurate methods to estimate two key quantities needed for their practical usage: noise bias and the Gaussian covariance matrix, fully accounting for survey geometry, with some results applicable to other cosmological probes. The methods are demonstrated using the latest public data releases of Hyper Suprime-Cam and the Dark Energy Survey collaborations, showing the presence of systematics in measurements and the validity of the covariance matrix estimate. The resulting power spectra, covariance matrices, null tests, and associated data necessary for a full cosmological analysis are made publicly available.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Sandra Baumgartner, Jaiyul Yoo
Summary: Recent analysis of Planck measurements suggests the possibility of a non-flat universe. This study re-examines light propagation in a non-flat universe and provides gauge-invariant expressions for various cosmological probes. With the inclusion of relativistic effects and the vector and tensor contributions, this study comprehensively investigates these probes in a non-flat universe, which will be crucial for constraining spatial curvature in future large-scale surveys.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Carlos Garcia-Garcia, David Alonso, Pedro G. Ferreira, Boryana Hadzhiyska, Andrina Nicola, Carles Sanchez, Anze Slosar
Summary: This paper introduces a method to quantify and propagate the uncertainties on the source redshift distribution in two different surveys sharing the same calibrating sample. The results show that the uncertainties on the redshift distributions do not significantly affect the final constraints on cosmological parameters.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Nicola Bartolo, Giovanni Battista Carollo, Sabino Matarrese, Luigi Pilo, Rocco Rollo
Summary: “We analyze the physical content of squeezed bispectra involving long-wavelength tensor perturbations and show that these modes cannot be gauged away, except in the unphysical limit of infinite wavelength, k = 0. This result has a direct implication on the validity of the Maldacena consistency relation, which is respected by a subclass of inflationary models. Consequently, future experiments can observe squeezed mixed correlators in the squeezed limit, similar to the scalar-scalar-scalar bispectrum, and they remain a key channel to study Early Universe physics and discriminate among different models of inflation.”
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
D. Zurcher, J. Fluri, V Ajani, S. Fischbacher, A. Refregier, T. Kacprzak
Summary: The next generation of weak lensing surveys will enable us to measure the matter distribution of the local universe with unprecedented precision, which opens up the possibility to resolve non-Gaussian features of the convergence field. We extend the methodology introduced in a previous forecast paper to match these new requirements and provide forecasts for the constraints on the $w$CDM parameters from stage 3 and 4 weak lensing surveys. Our results show that the combination of different summary statistics, including the angular power spectrum, peak counts, and Minkowski functionals following Starlet filtering, significantly improves the constraints on cosmology.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Dominik Zurcher, Janis Fluri, Raphael Sgier, Tomasz Kacprzak, Alexandre Refregier
Summary: The study compared the constraining power of three map-based non-Gaussian statistics with the angular power spectrum in the Omega(m)-sigma(8) plane, finding that non-Gaussian statistics provide tighter constraints. A combination of non-Gaussian statistics and the angular power spectrum increased the constraining power and reduced the error on S8.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Rajorshi Sushovan Chandra, Tarun Souradeep
Summary: The study uses an improved deconvolution algorithm to reconstruct the Primordial Power Spectrum from Weak Lensing Power Spectrum, providing an independent method to observe and constrain the spectrum. The Weak Lensing Power Spectrum is cleaner and provides unique features over different K scales compared to the CMB Temperature Power Spectrum.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Jia-Xi Feng, Fengge Zhang, Xian Gao
Summary: In this study, we investigate the polarized properties of scalar induced gravitational waves (SIGWs) in the Chern-Simons gravity with a dynamical scalar field. We find that the correction from the parity-violating Chern-Simons term is negligible on large scales, indicating a very small degree of circular polarization for these gravitational waves.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Francesca Lepori, Sebastian Schulz, Julian Adamek, Ruth Durrer
Summary: We present for the first time halo number counts and their two-point statistics extracted from relativistic N-body simulations. The halo catalogues are built from the relativistic N-body code gevolution, and the observed positions and redshifts of the sources are computed using a non-perturbative ray-tracing method. We investigate the validity and limitations of linear bias prescription and test a second-order perturbative bias expansion for angular statistics. We also extract the cross-correlation of halo number counts and lensing convergence, finding consistent linear bias estimates and the importance of considering magnification effects.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Elena Kozlikin, Robert Lilow, Felix Fabis, Matthias Bartelmann
Summary: By comparing the newly developed particle-based Kinetic Field Theory with the established Eulerian Standard Perturbation Theory, we find that in the non-interacting regime of free-streaming kinematics, Kinetic Field Theory contains a complete resummation of Standard Perturbation Theory, and the exact solution of Kinetic Field Theory cannot be recovered in any finite order of Standard Perturbation Theory. This suggests that Kinetic Field Theory may provide a better starting point for perturbative treatments of non-linear structure formation.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Farbod Hassani, Shant Baghram, Hassan Firouzjahi
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2016)
Article
Astronomy & Astrophysics
Shahram Khosravi, Amir Mollazadeh, Shant Baghram
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2016)
Article
Astronomy & Astrophysics
Hoda Ghodsi, Shant Baghram, Farhabg Habibi
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2017)
Article
Astronomy & Astrophysics
Farhang Habibi, Shant Baghram, Saeed Tavasoli
INTERNATIONAL JOURNAL OF MODERN PHYSICS D
(2018)
Article
Astronomy & Astrophysics
Farnik Nikakhtar, Mohammadreza Ayromlou, Shant Baghram, Sohrab Rahvar, M. Reza Rahimi Tabar, Ravi K. Sheth
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2018)
Article
Astronomy & Astrophysics
Shant Baghram
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2019)
Article
Astronomy & Astrophysics
Shahram Khosravi, Amirabbas Ghazizadeh, Shant Baghram
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2019)
Article
Astronomy & Astrophysics
Mohammad Ansari Fard, Sina Taamoli, Shant Baghram
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2019)
Article
Astronomy & Astrophysics
Hamed Kameli, Shant Baghram
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2020)
Article
Astronomy & Astrophysics
Alireza Maleki, Shant Baghram, Sohrab Rahvar
Article
Astronomy & Astrophysics
Alireza Maleki, Shant Baghram, Sohrab Rahvar
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Physics, Fluids & Plasmas
Shant Baghram, Farnik Nikakhtar, M. Reza Rahimi Tabar, S. Rahvar, Ravi K. Sheth, Klaus Lehnertz, Muhammad Sahimi
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Astronomy & Astrophysics
Nima Khosravi, Shant Baghram, Niayesh Afshordi, Natacha Altamirano
Article
Astronomy & Astrophysics
Farnik Nikakhtar, Shant Baghram