scholarly journals Model-independent distance measurements from gamma-ray bursts and constraints on dark energy

2008 ◽  
Vol 78 (12) ◽  
Author(s):  
Yun Wang
Keyword(s):  
Dark Energy ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Distance Measurements ◽  
Model Independent

scholarly journals Model-independent calibrations of gamma-ray bursts using machine learning

2021 ◽  
Vol 503 (3) ◽  
pp. 4581-4600
Author(s):  
Orlando Luongo ◽  
Marco Muccino
Keyword(s):  
Machine Learning ◽  
Dark Energy ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Bayesian Regression ◽  
Machine Learning Techniques ◽  
Acoustic Oscillations ◽  
Chi Square ◽  
Model Independent ◽  
Chi Square Analysis

ABSTRACT We alleviate the circularity problem, whereby gamma-ray bursts are not perfect distance indicators, by means of a new model-independent technique based on Bézier polynomials. We use the well consolidate Amati and Combo correlations. We consider improved calibrated catalogues of mock data from differential Hubble rate points. To get our mock data, we use those machine learning scenarios that well adapt to gamma-ray bursts, discussing in detail how we handle small amounts of data from our machine learning techniques. We explore only three machine learning treatments, i.e. linear regression, neural network, and random forest, emphasizing quantitative statistical motivations behind these choices. Our calibration strategy consists in taking Hubble’s data, creating the mock compilation using machine learning and calibrating the aforementioned correlations through Bézier polynomials with a standard chi-square analysis first and then by means of a hierarchical Bayesian regression procedure. The corresponding catalogues, built up from the two correlations, have been used to constrain dark energy scenarios. We thus employ Markov chain Monte Carlo numerical analyses based on the most recent Pantheon supernova data, baryonic acoustic oscillations, and our gamma-ray burst data. We test the standard ΛCDM model and the Chevallier–Polarski–Linder parametrization. We discuss the recent H0 tension in view of our results. Moreover, we highlight a further severe tension over Ωm and we conclude that a slight evolving dark energy model is possible.

scholarly journals DESAlert: Enabling Real-Time Transient Follow-Up with Dark Energy Survey Data

2016 ◽  
Vol 33 ◽  
Author(s):  
A. Poci ◽  
K. Kuehn ◽  
T. Abbott ◽  
F. B. Abdalla ◽  
S. Allam ◽  
...  
Keyword(s):  
Dark Energy ◽  
Real Time ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Host Galaxies ◽  
Gamma Ray Burst ◽  
Dark Energy Survey ◽  
Data Products ◽  
Energy Survey

AbstractThe Dark Energy Survey is undertaking an observational programme imaging 1/4 of the southern hemisphere sky with unprecedented photometric accuracy. In the process of observing millions of faint stars and galaxies to constrain the parameters of the dark energy equation of state, the Dark Energy Survey will obtain pre-discovery images of the regions surrounding an estimated 100 gamma-ray bursts over 5 yr. Once gamma-ray bursts are detected by, e.g., the Swift satellite, the DES data will be extremely useful for follow-up observations by the transient astronomy community. We describe a recently-commissioned suite of software that listens continuously for automated notices of gamma-ray burst activity, collates information from archival DES data, and disseminates relevant data products back to the community in near-real-time. Of particular importance are the opportunities that non-public DES data provide for relative photometry of the optical counterparts of gamma-ray bursts, as well as for identifying key characteristics (e.g., photometric redshifts) of potential gamma-ray burst host galaxies. We provide the functional details of the DESAlert software, and its data products, and we show sample results from the application of DESAlert to numerous previously detected gamma-ray bursts, including the possible identification of several heretofore unknown gamma-ray burst hosts.

Gamma-ray bursts and cosmology

2007 ◽  
Vol 365 (1854) ◽  
pp. 1363-1376 ◽  
Author(s):  
D.Q Lamb
Keyword(s):  
Dark Energy ◽  
Early Universe ◽  
Gamma Ray ◽  
High Redshift ◽  
Gamma Ray Bursts ◽  
Current Status ◽  
Scientific Results ◽  
Short Grbs ◽  
Very High

I review the current status of the use of gamma-ray bursts (GRBs) as probes of the early Universe and cosmology. I describe the promise of long GRBs as probes of the high redshift ( z >4) and very high redshift ( z >5) Universe, and several key scientific results that have come from observations made possible by accurate, rapid localizations of these bursts by Swift. I then estimate the fraction of long GRBs that lie at very high redshifts and discuss ways in which it may be possible to rapidly identify—and therefore study—a larger number of these bursts. Finally, I discuss the ways in which both long and short GRBs can be made ‘standard candles’ and used to constrain the properties of dark energy.

scholarly journals Master Robotic Net

2010 ◽  
Vol 2010 ◽  
pp. 1-6 ◽  
Author(s):  
Vladimir Lipunov ◽  
Victor Kornilov ◽  
Evgeny Gorbovskoy ◽  
Nikolaj Shatskij ◽  
Dmitry Kuvshinov ◽  
...  
Keyword(s):  
Dark Energy ◽  
Solar System ◽  
Gamma Ray ◽  
Optical Emission ◽  
Gamma Ray Bursts ◽  
Sky Survey ◽  
Single Night

The main goal of the MASTER-Net project is to produce a unique fast sky survey with all sky observed over a single night down to a limiting magnitude of 19-20. Such a survey will make it possible to address a number of fundamental problems: search for dark energy via the discovery and photometry of supernovae (including SNIa), search for exoplanets, microlensing effects, discovery of minor bodies in the Solar System, and space-junk monitoring. All MASTER telescopes can be guided by alerts, and we plan to observe prompt optical emission from gamma-ray bursts synchronously in several filters and in several polarization planes.

scholarly journals Constraints onw0andwaof dark energy from high-redshift gamma-ray bursts

2009 ◽  
Vol 394 (1) ◽  
pp. L31-L35 ◽  
Author(s):  
Ryo Tsutsui ◽  
Takashi Nakamura ◽  
Daisuke Yonetoku ◽  
Toshio Murakami ◽  
Sachiko Tanabe ◽  
...  
Keyword(s):  
Dark Energy ◽  
Gamma Ray ◽  
High Redshift ◽  
Gamma Ray Bursts
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