Swift Gamma-Ray Bursts: A 3D Step Toward Standard Candles

[bystander]

Swift Gamma-Ray Bursts: A 3D Step Toward Standard Candles
NASA | Goddard | Swift | 2016 June 20

[img3="A typical long (> 2 s) duration Gamma-Ray Burst that shows the peak luminosity, the plateau luminosity and the time at plateau end. The combination of these three parameters were found to work the best as distance indicators."]http://swift.gsfc.nasa.gov/news/2016/GRBanatomy.jpg[/img3][hr][/hr]

A new way to use the most powerful explosions in the Universe to calibrate its expansion has been developed by a team of researchers (Sergey Postnikov, Xavier Hernandez from Institute of Astronomy , UNAM, and Michal Ostrowski from the Astronomical Observatory of Jagiellonian University) led by Marie Curie Outgoing Fellow at Stanford University, Maria Dainotti. Dainotti recently presented the results of her team's work at a press conference at the 228th meeting of the American Astronomical Society. Dainotti's three-dimensional analysis shows that a specific population of gamma-ray bursts can be used to provide an independent measurement of the cosmic distance scale. Since gamma-ray bursts are even brighter than supernovae, this new technique has the potential to extend the cosmic ruler to greater distances than are currently possible.

Astronomers refer to these cosmic rulers as "standard candles" - objects with a known intrinsic luminosity. Once the absolute luminosity is known, the distance to that object can be calculated based on its measured brightness. For example, a 100 Watt lightbulb will appear four times dimmer when it is twice as far away.

"This 3D correlation, since it is the tightest among the prompt-afterglow ones so far in the literature, will offer the opportunity to estimate the cosmological parameters and then allows a direct investigation of the cosmological evolution of the Universe up to epoch of reionization", said Dr. Dainotti. ...

A fundamental plane for long gamma-ray bursts with X-ray plateaus - Maria Giovanna Dainotti et al

• arXiv.org > astro-ph > arXiv:1604.06840 > 23 Apr 2016 (v1), 04 Jun 2016 (v2)

[bystander]

A 3-D Step Toward Sorting Out the Gamma-Ray-Burst Zoo
Italian National Institute of Astrophysics | 2017 Oct 13

A powerful tool for characterizing and classifying gamma-ray bursts (GRBs) to allow their use as tracers of the expansion history of the universe has recently been presented by an international team of researchers led by Dr. Maria Dainotti, outgoing Marie Curie Fellow at INAF, Italy, and Stanford University, USA, and assistant professor at Jagiellonian University, Poland. The work, which has been published in the Astrophysical Journal, is a statistical analysis of the properties of the yet mysterious GRBs, aimed at determining a sub-group of GRBs and investigating the physical origin of these systems.

GRBs are the most powerful high energy events known, lasting anything between a few seconds to a few hours: during their short-lived phase of very high-energy gamma-ray emission (called the prompt), they emit the same amount of energy the Sun releases over its entire lifetime. Thus, they are detected out to distances such that their light has been travelling towards us since the universe was only a thousandth of its current size. Despite having been observed for decades, there is still precious little definitively known regarding the physical mechanisms which produce them. There is in fact no shortage of proposed origins, including the explosions of extremely massive stars, the merger of two neutron stars or the spin-down of magnetized massive stars.

Not only is the interest in GRB studies geared towards coaxing out their origins, but, as they can be detected out to much earlier epochs than supernovae, if astronomers could ascertain their detailed physical characteristics, in particular the intrinsic luminosity of each distinct observed GRB, they could be used to trace the expansion history of the universe out to significantly more remote cosmological times than currently possible. ...

A Study of the Gamma-Ray Burst Fundamental Plane - Maria Giovanna Dainotti et al

• arXiv.org > astro-ph > arXiv:1704.04908 > 17 Apr 2017 (v1), 04 Sep 2017 (v2)