Dr. Tetsuya Hashimoto 橋本哲也 (NTNU)
"Recent three discoveries from NTHU cosmology group"
時間/地點: 2019-11-29 14:00 [S4-1013]
摘要:
I will present my recent papers on (i) the luminosity-duration
relation of fast radio bursts (FRBs), (ii) ALMA observations of
Gamma-Ray Burst (GRB) host galaxies, and (iii) a blue cluster in the
local Universe. Brief summaries of each paper are as follows.
(i) Luminosity-duration relation of fast radio bursts
We discovered an empirical correlation between luminosity and duration
of FRBs. We propose a new distance measure using the relation of FRBs,
which can reach more distant Universe than type Ia supernovae in
quantity. This method can potentially reveal the time variability of
the dark energy, which is one of the central foci of observational
cosmology.
(ii) SFRs of two GRB host galaxies at z~2 and a [CII] deficit observed
with ALMA
We discovered a new parameter to characterize GRB host galaxies, [CII]
deficit, by overcoming a serious dust-extinction problem of GRB host
galaxies. Possible parameters controlling the deficit include the
metallicity, initial mass function, and gas density.
(iii) A young galaxy cluster in the old Universe
We discovered a 'blue cluster', that is a local galaxy cluster with an
unprecedentedly high fraction of blue star-forming galaxies yet hosted
by a massive dark matter halo. The blue cluster challenges the current
standard understanding of galaxy formation under the Lambda CDM
Universe.