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The isotropy of the late Universe is an assumption greatly used in astronomy. However, many studies have recently reported deviations from isotropy with a definitive conclusion yet to be made. New, independent methods to robustly test the…

Cosmology and Nongalactic Astrophysics · Physics 2020-04-09 K. Migkas , G. Schellenberger , T. H. Reiprich , F. Pacaud , M. E. Ramos-Ceja , L. Lovisari

In this work, we combine ellipticity and major axis position angle measurements from the Sloan Digital Sky Server Data Release 16 (SDSS DR16) with the group finder algorithm of Rodriguez \& Merch\'an to determine the alignment of the…

Astrophysics of Galaxies · Physics 2022-06-01 Facundo Rodriguez , Manuel Merchán , M. Celeste Artale

We test claims of large-scale anisotropy in the local expansion rate using cluster scaling relations as distance indicators. Using a Bayesian forward model, we jointly fit the X-ray luminosity--temperature (LT) and thermal…

Cosmology and Nongalactic Astrophysics · Physics 2026-02-06 Tariq Yasin , Richard Stiskalek , Harry Desmond , Sebastian von Hausegger , Pedro G. Ferreira

The arrival directions of Galactic cosmic rays (CRs) are highly isotropic. This is expected from the presence of turbulent magnetic fields in our Galactic environment that repeatedly scatter charged CRs during propagation. However, various…

High Energy Astrophysical Phenomena · Physics 2017-04-05 Markus Ahlers , Philipp Mertsch

We perform observational tests of statistical isotropy using data from large-scale structure surveys spanning a wide range of wavelengths. Using data from 2MASS, 2MRS, and NVSS galaxies, and BATSE gamma-ray bursts, we constrain the…

Cosmology and Nongalactic Astrophysics · Physics 2012-12-10 Cameron Gibelyou , Dragan Huterer

We identify low redshift clusters and groups in the Sloan Digital Sky Survey (SDSS) and estimate their kinetic and correlation potential energies. We compare the distribution of these energies to the predictions by Yang and Saslaw (2012)…

Cosmology and Nongalactic Astrophysics · Physics 2012-06-22 Abel Yang , William C. Saslaw

We probe the isotropy of the Universe with the largest all-sky photometric redshift dataset currently available, namely WISE~$\times$~SuperCOSMOS. We search for dipole anisotropy of galaxy number counts in multiple redshift shells within…

Cosmology and Nongalactic Astrophysics · Physics 2018-04-11 C. A. P. Bengaly , C. P. Novaes , H. S. Xavier , M. Bilicki , A. Bernui , J. S. Alcaniz

Analyses of recent cosmic microwave background (CMB) observations have provided increasing indications for the existence of large scale anisotropy in the universe. Given the far reaching consequences of such an anisotropy for our…

Astrophysics · Physics 2009-09-29 A. Bernui , B. Mota , M. J. Reboucas , R. Tavakol

The assumption of homogeneity and isotropy on large scales is one of the main hypotheses of the standard cosmology. In this paper, we test the hypothesis of isotropy from the two-point angular correlation function of 2626 gamma-ray bursts…

Cosmology and Nongalactic Astrophysics · Physics 2019-10-16 Uendert Andrade , Carlos A. P. Bengaly , Jailson S. Alcaniz , Salvatore Capozziello

We report the first test of isotropy of the Universe in the matter dominated epoch using the Lyman-$\alpha$ forest data from the high redshift quasars ($z>2$) from SDSS-III BOSS-DR9 datasets. Using some specified data cuts, we obtain the…

Cosmology and Nongalactic Astrophysics · Physics 2017-12-25 Dhiraj Kumar Hazra , Arman Shafieloo

We calculate the large-scale cosmic-ray (CR) anisotropies predicted for a range of Goldreich-Sridhar (GS) and isotropic models of interstellar turbulence, and compare them with IceTop data. In general, the predicted CR anisotropy is not a…

High Energy Astrophysical Phenomena · Physics 2017-02-07 Gwenael Giacinti , John G. Kirk

Recently, an anisotropic cosmological model was proposed. An arbitrary 1-form, which picks out a privileged axis in the universe, was added to the Friedmann-Robertson-Walker line element. The distance-redshift relation was modified such…

Cosmology and Nongalactic Astrophysics · Physics 2014-05-14 Zhe Chang , Xin Li , Hai-Nan Lin , Sai Wang

We present the results of the 2MASS Redshift Survey (2MRS), a ten-year project to map the full three-dimensional distribution of galaxies in the nearby Universe. The 2 Micron All-Sky Survey (2MASS) was completed in 2003 and its final data…

Our observations of the Universe are fundamentally anisotropic, with data from galaxies separated transverse to the line of sight coming from the same epoch while that from galaxies separated parallel to the line of sight coming from…

Cosmology and Nongalactic Astrophysics · Physics 2014-03-26 Eric V. Linder , MinJi Oh , Teppei Okumura , Cristiano G. Sabiu , Yong-Seon Song

We present a novel approach to disentangle two key contributions to the largest-scale anisotropy of the galaxy distribution: (i) the intrinsic dipole due to clustering and anisotropic geometry, and (ii) the kinematic dipole due to our…

Cosmology and Nongalactic Astrophysics · Physics 2021-11-09 Tobias Nadolny , Ruth Durrer , Martin Kunz , Hamsa Padmanabhan

The galaxy distributions along the line-of-sight are significantly contaminated by the uncertainty on redshift measurements obtained through multiband photometry, which makes it difficult to get cosmic distance information measured from…

Cosmology and Nongalactic Astrophysics · Physics 2019-07-15 Srivatsan Sridhar , Yong-Seon Song

We study galaxy evolution and spatial patterns in the surroundings of a sample of 2dF groups. Our aim is to find evidence of galaxy evolution and clustering out to 10 times the virial radius of the groups and so redefine their properties…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 A. L. B. Ribeiro , M. Trevisan , P. A. A. Lopes , A. C. Schilling

An analysis of the Cosmological Constant $\Omega_\Lambda$ fitted to subsamples of the Pantheon+ Type Ia SN sample spanning 2$\pi$ sterradians for a grid of 432 pole positions covering the whole sky reveals two large scale asymmetries. One…

Cosmology and Nongalactic Astrophysics · Physics 2024-06-04 Alejandro Clocchiatti , Ósmar Rodríguez , Ariel Órdenes Morales , Benjamín Cuevas-Tapia

The hypothesis that the late Universe is isotropic and homogeneous is adopted by most cosmological studies. The expansion rate $H_0$ is thought to be spatially constant, while bulk flows are often presumed to be negligible compared to the…

Cosmology and Nongalactic Astrophysics · Physics 2021-06-02 K. Migkas , F. Pacaud , G. Schellenberger , J. Erler , N. T. Nguyen-Dang , T. H. Reiprich , M. E. Ramos-Ceja , L. Lovisari

We present evidence of anisotropic galaxy assembly bias in the Baryon Oscillation Spectroscopic Survey Data Release 12 galaxy sample at a level exceeding $5\sigma$. We use measurements of the line-of-sight velocity dispersion $\sigma_\star$…

Cosmology and Nongalactic Astrophysics · Physics 2020-11-11 Andrej Obuljen , Will J. Percival , Neal Dalal