Testing Isotropic Universe Using the Gamma-Ray Burst Data of Fermi / GBM

Abstract

The sky distribution of Gamma-Ray Bursts (GRBs) has been intensively studied by various groups for more than two decades. Most of these studies test the isotropy of GRBs based on their sky number density distribution. In this work we propose an approach to test the isotropy of the Universe through inspecting the isotropy of the properties of GRBs such as their duration, fluences and peak fluxes at various energy bands and different time scales. We apply this method on the {\em Fermi} / Gamma-ray Burst Monitor (GBM) data sample containing 1591 GRBs. The most noticeable feature we found is near the Galactic coordinates $l\approx 30^{\circ }$, $b\approx 15^{\circ }$ and radius $r\approx 20^{\circ }-40^{\circ }$. The inferred probability for the occurrence of such an anisotropic signal (in a random isotropic sample) is derived to be less than a percent in some of the tests while the other tests give results consistent with isotropy. These are based on the comparison of the results from the real data with the randomly shuffled data samples. Considering large number of statistics we used in this work (which some of them are correlated to each other) we can anticipate that the detected feature could be result of statistical fluctuations. Moreover, we noticed a considerably low number of GRBs in this particular patch which might be due to some instrumentation or observational effects that can consequently affect our statistics through some systematics. Further investigation is highly desirable in order clarify about this result, e.g. utilizing a larger future {\em Fermi} / GBM data sample as well as data samples of other GRB missions and also looking for possible systematics.

arXiv comment17 pages, 10 figures, 4 tables, accepted for publication in The Astrophysical Journal

References in corpus (62)

• The Fermi Gamma-Ray Burst Monitor
• The Physics of Gamma-Ray Bursts and Relativistic Jets
• Planck 2013 results. XXIII. Isotropy and statistics of the CMB
• Planck 2015 results. XVI. Isotropy and statistics of the CMB
• The Fermi GBM Gamma-Ray Burst Spectral Catalog: Four Years Of Data
• A Map of the Universe
• Three types of gamma-ray bursts
• Cosmic homogeneity demonstrated with luminous red galaxies
• The 2nd Fermi GBM Gamma-Ray Burst Catalog: The First Four Years
• The 3rd Fermi GBM Gamma-Ray Burst Catalog: The First Six Years
• The WiggleZ Dark Energy Survey: the transition to large-scale cosmic homogeneity
• Probing the anisotropic local universe and beyond with SNe Ia data
• 2-Point Correlations in the COBE DMR 4-Year Anisotropy Maps
• Extragalactic Radio Sources and the WMAP Cold Spot
• A 3rd Class of Gamma Ray Bursts?
• BATSE Observations of the Large-Scale Isotropy of Gamma-Ray Bursts
• Power asymmetry in WMAP and Planck temperature sky maps as measured by a local variance estimator
• A structure in the early universe at z ~ 1.3 that exceeds the homogeneity scale of the R-W concordance cosmology
• Probing the isotropy of cosmic acceleration traced by Type Ia supernovae
• Measuring cosmic bulk flows with Type Ia Supernovae from the Nearby Supernova Factory
• Detailed Classification of Swift's Gamma-Ray Bursts
• Further Study of the Gamma-Ray Bursts Duration Distribution
• Possible structure in the GRB sky distribution at redshift two
• Classification of Swift's gamma-ray bursts
• Seeing patterns in noise: Gigaparsec-scale `structures' that do not violate homogeneity
• A giant ring-like structure at 0.78<z<0.86 displayed by GRBs
• New data support the existence of the Hercules-Corona Borealis Great Wall
• Reclassification of gamma-ray bursts
• A Remarkable Angular Distribution of the Intermediate Subclass of Gamma-Ray Bursts
• Statistical Study of Observed and Intrinsic Durations among BATSE and Swift/BAT GRBs
• Classification of Gamma-Ray Burst durations using robust model-comparison techniques
• Testing the Randomness in the Sky-Distribution of Gamma-Ray Bursts
• A comparison of the gamma-ray bursts detected by BATSE and Swift
• Evidence for anisotropy in the distribution of short-lived gamma-ray bursts
• Anisotropic dark energy and ellipsoidal universe
• Crossing Statistic: Reconstructing the Expansion History of the Universe
• Classification of BeppoSAX's Gamma-Ray Bursts
• Probing bulk flow with nearby SNe Ia data
• A distinct peak-flux distribution of the third class of gamma-ray bursts: A possible signature of X-ray flashes?
• The Angular Power Spectrum of BATSE 3B Gamma-Ray Burst
• Anisotropy in the all-sky distribution of galaxy morphological types
• Searching for a dipole modulation in the large-scale structure of the Universe
• Searching for differences in Swift's intermediate GRBs
• Testing Isotropy in the Local Universe
• The duration distribution of Swift Gamma-Ray Bursts
• Search for Gamma-Ray Burst Classes with the RHESSI Satellite
• An intrinsic anisotropy in the angular distribution of gamma-ray bursts
• 2MASS Constraints on the Local Large-Scale Structure: A Challenge to LCDM?
• On the Spectral Lags and Peak-Counts of the Gamma-Ray Bursts Detected by the RHESSI Satellite
• Crossing Statistic: Bayesian interpretation, model selection and resolving dark energy parametrization problem
• The Crossing Statistic: Dealing with Unknown Errors in the Dispersion of Type Ia Supernovae
• Investigation of Redshift- and Duration-Dependent Clustering of Gamma-ray Bursts
• Study of Very Short GRB: New Results from BATSE and KONUS
• On the large-scale angular distribution of short-Gamma ray bursts
• Testing the anisotropy in the angular distribution of $Fermi$/GBM gamma-ray bursts
• Testing the homogeneity of the Universe using gamma-ray bursts
• Searching for electromagnetic counterpart of LIGO gravitational waves in the Fermi GBM data with ADWO
• The 2MASS galaxy angular power spectrum: Probing the galaxy distribution to Gigaparsec scales
• Two Dimensional Classification of the Swift/BAT GRBs
• On the Connection of Gamma-Ray Bursts and X-Ray Flashes in the BATSE and RHESSI Databases
• Anisotropy in the angular distribution of the long gamma-ray bursts?
• Direction Dependent Background Fitting for the Fermi GBM Data

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• Probing cosmic isotropy with a new X-ray galaxy cluster sample through the $L_{\text{X}}-T$ scaling relation
• Complexity and Isotropization based Extended Models in the context of Electromagnetic Field: An Implication of Minimal Gravitational Decoupling
• Study of Decoupled Cosmological Solutions in $f(\mathbb{R},\mathbb{T})$ Theory
• Cosmological Solutions through Gravitational Decoupling in $f(\mathcal{R},\mathcal{T},{\mathcal{R}}_{\mathrm{ab}}{\mathcal{T}}^{\mathrm{ab}})$ Gravity
• Large angular scale multipoles at redshift ~0.8
• Cosmology Intertwined: A Review of the Particle Physics, Astrophysics, and Cosmology Associated with the Cosmological Tensions and Anomalies
• The scale of homogeneity in the local Universe with the ALFALFA catalogue
• Revisiting the statistical isotropy of GRB sky distribution
• Role of Non-conserved Gravity Theory and Electric Charge in Constructing Complexity-free Stellar Models: A Novel Approach under Non-minimal Coupling
• Update on Testing the Isotropy of the Properties of Gamma-Ray Bursts
• Testing the Cosmological Principle in the radio sky
• An Oppositeness in the Cosmology: Distribution of the Gamma-Ray Bursts and the Cosmological Principle
• Evidence of isotropy at large-scale from polarizations of radio sources
• Extending Finch-Skea Isotropic Model to Anisotropic Domain in Modified $f(\mathcal{R},\mathcal{T})$ Gravity
• Space-time second-quantization effects and the quantum origin of cosmological constant in covariant quantum gravity
• Does the GRB Duration Depend on Redshift?
• Implications of Rastall Theory on Stellar Solutions admitting Vanishing Complexity: A New Perspective
• Examining the local Universe isotropy with galaxy cluster velocity dispersion scaling relations
• Dipolar fluence distribution of statistically isotropic FERMI gamma-ray bursts
• Physical Features of Geometrically Deformed Anisotropic Charged Three-dimensional BTZ Black Holes
• Scanning the Universe for Large-Scale Structures using Gamma-Ray Bursts
• Measuring cosmic dipole with the GRB luminosity-time relation
• Reanalysing large-scale structure using an updated gamma-ray burst spatial density approach
• Probing dipole and quadrupole anisotropy in Gamma-ray bursts from Swift dataset