Using shattering explosions to measure the universe.
A multinational team of 23 scientists, led by Maria Dainotti, assistant professor at the National Astronomical Observatory of Japan (NAOJ), has analyzed archival data of massive cosmic explosions produced by the death of stars and discovered a new method to measure distances in the most distant limits of the Universe.
It’s hard to get a sense of depth in space since there are no landmarks. One method used by astronomers is to look for “standard candles,” objects or events whose absolute brightness (what you would see if you were standing next to it) is determined by the underlying physics to be constant.
This makes it possible to estimate the distance to the standard candle and, by extension, to other objects in the same region by comparing the predicted absolute brightness with the apparent brightness (what is actually seen from Earth). The scarcity of standard candles bright enough to be seen from more than 11 billion light-years away has hampered research into the distant Universe. Gamma-ray bursts (GRBs), bursts of radiation caused by the demise of massive stars, are visible, although their brightness depends on the characteristics of the explosion.
Facing the challenge of using these bright events as standard candles, the team examined archival data for visible-light observations of 500 GRBs taken by world-class telescopes such as the Subaru Telescope (owned and operated by NAOJ) , RATIR and satellites such as the Neil Gehrels Swift Observatory.
Scientists found a class of 179 GRBs with common features and likely caused by similar events by studying the light curve pattern of how the GRB brightens and dims over time. The team was able to determine a unique brightness and distance for each GRB based on the characteristics of the light curves, which could be used as a cosmological tool.
These findings will provide new insights into the mechanics behind this class of GRBs and provide a new standard candle for observing the distant Universe. Lead author Dainotti had previously found a similar pattern in X-ray observations of GRBs, but visible-light observations have been revealed to be more accurate in determining cosmological parameters.
Reference: “Two-dimensional and three-dimensional optical fundamental plane correlations for nearly 180 gamma-ray afterglows with Swift/UVOT, RATIR, and the Subaru Telescope” by MG Dainotti, S. Young, L. Li, D. Levine, KK Kalinowski , DA Kann, B. Tran, L. Zambrano-Tapia, A. Zambrano-Tapia, SB Cenko, M. Fuentes, EG Sánchez-Vázquez, SR Oates, N. Fraija, RL Becerra, AM Watson, NR Butler, JJ González , AS Kutyrev, WH Lee, JX Prochaska, E. Ramirez-Ruiz, MG Richer, and S. Zola, 21 Jul 2022, The Astrophysical Journal Supplement Series.
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