Related papers: Testing Isotropy in the Local Universe
Three methods for detecting and characterizing structure in point data, such as that generated by redshift surveys, are described: classification using self-organizing maps, segmentation using Bayesian blocks, and density estimation using…
Morphological classification conveys abundant information on the formation, evolution, and environment of galaxies. In this work, we refine the two-step galaxy morphological classification framework ({\tt\string USmorph}), which employs a…
Recent cosmological modeling efforts have shown that a local underdensity on scales of a few hundred Mpc (out to z ~ 0.1), could produce the apparent acceleration of the expansion of the universe observed via type Ia supernovae. Several…
Two new luminosity functions of galaxies can be built starting from three and four parameter generalized gamma distributions. In the astrophysical conversion, the number of parameters increases by one, due to the addition of the overall…
In this study we investigate potential large-angle anisotropies in the angular distribution of the cosmological parameters $H_0$ (the Hubble constant) and $\Omega_m$ (the matter density) in the flat-$\Lambda$CDM framework, using the…
We investigate the weak lensing shear due to dark matter galaxy halos whose mass distributions, as projected on the sky, are nearly elliptical. The shear pattern due to these halos is anisotropic about the lens centers and we quantify the…
We study a set of solar neighborhood ($d < 3$ kpc) stars from Gaia Data Release 2 to determine azimuthal star count differences, i.e., left and right of the line from the Galactic center through the sun - and compare these differences north…
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…
The determination of the density parameter $\Omega_0$ from the large-scale distribution of galaxies is one of the major goals of modern cosmology. However, if galaxies are biased tracers of the underlying mass distribution, linear…
We present a new maximum likelihood method for the calculation of galaxy luminosity functions from multi-band photometric surveys without spectroscopic data. The method evaluates the likelihood of a trial luminosity function by directly…
Using the stellar photometry catalogue based on the latest data release (DR4) of the Sloan Digital Sky Survey (SDSS), a study of the Galactic structure using star counts is carried out for selected areas of the sky. The sample areas are…
The assumption that the universe is homogeneous and isotropic on large scales is one of the fundamental postulates of cosmology. We have tested the large scale homogeneity of the galaxy distribution in the Sloan Digital Sky Survey Data…
We present density split statistics, a framework that studies lensing and counts-in-cells as a function of foreground galaxy density, thereby providing a large-scale measurement of both 2-point and 3-point statistics. Our method extends our…
The luminosity functions of galaxies and quasars provide invaluable information about galaxy and quasar formation. Estimating the luminosity function from magnitude limited samples is relatively straightforward, provided that the distances…
We introduce a new method for testing departure from isotropy of points on a sphere based on an enhanced form of the two-point correlation function that we named 2pt+. This method uses information from the two extra variables that define…
We exploit observations at 1.25 mm with the ESO-SEST telescope of a southern galaxy sample, selected from the IRAS PSC and complete to $S_{60}=2 Jy$, to derive the FIR and mm luminosity functions and the conditional probability…
The Telescope Array (TA) experiment is located in the western desert of Utah, USA, and observes ultra high energy cosmic rays (UHECRs) in the Northern hemisphere. At the highest energies, $E>10$~EeV, the shape of cosmic ray energy spectrum…
The distribution of satellite galaxies relative to isolated host galaxies in the Sloan Digital Sky Survey (SDSS) is investigated. Host-satellite systems are selected using three different methods, yielding samples of ~3300, ~1600, and \~950…
We measure the non-axisymmetry in the luminosity distribution in the inner few kpc of the remnants of advanced mergers of galaxies with a view to understand the relaxation in the central regions. For this, we analyze the images from the…
We introduce a new mathematical tool (a direction-dependent probe) to analyse the randomness of purported isotropic Gaussian random fields on the sphere. We apply the probe to assess the full-sky cosmic microwave background (CMB)…