29 research outputs found
Neutrino emissions in all flavors up to the pre-bounce of massive stars and the possibility of their detections
This paper is a sequel to our previous one (Kato et al.2015), which
calculated the luminosities and spectra of electron-type anti-neutrinos
('s) from the progenitors of core-collapse supernovae. Expecting
that a capability to detect electron-type neutrinos ('s) will increase
dramatically with the emergence of liquid-argon detectors such as DUNE, we
broaden the scope in this study to include all-flavors of neutrinos emitted
from the pre-bounce phase. We pick up three progenitor models of an electron
capture supernova (ECSN) and iron-core collapse supernovae (FeCCSNe). We find
that the number luminosities reach and
at maximum for and ,
respectively. We also estimate the numbers of detection events at terrestrial
neutrino detectors including DUNE, taking flavor oscillations into account and
assuming the distance to the progenitors to be 200 pc. It is demonstrated that
's from the ECSN-progenitor will be undetected at almost all
detectors, whereas we will be able to observe 15900 's at DUNE
for the inverted mass hierarchy. From the FeCCSN-progenitors, the number of
events will be largest for JUNO, 200-900 's,
depending on the mass hierarchy whereas the number of events at DUNE is
2100 for the inverted mass hierarchy. These results imply that the
detection of 's is useful to distinguish FeCCSN- from
ECSN-progenitors, while 's will provide us with detailed information on
the collapse phase regardless of the type and mass of progenitor.Comment: 22 pages, 14 figures, 4 tables, accepted to Ap
Pulsational Pair-instability Supernovae. II. Neutrino Signals from Pulsations and Their Detection by Terrestrial Neutrino Detectors
A Pulsational Pair-instability supernova (PPISN) evolves from a massive star with a mass ~80–140 M⊙ that develops electron–positron pair-instability after hydrostatic He-burning in the core has finished. In Leung et al. (Paper I), we examined the evolutionary tracks and the pulsational mass-loss history of this class of stars. In this paper, we analyze the thermodynamical history to explore the neutrino observables of PPISNe. We compute the neutrino light curves and spectra during pulsation. We then study the detailed neutrino emission profiles of these stars and estimate the expected neutrino detection count for different terrestrial neutrino detectors, including, e.g., KamLAND and Super-Kamiokande. Finally, we compare the neutrino pattern of PPISN with other types of supernovae based on a canonical 10 kt detector. The predicted neutrino signals can provide an early warning for telescopes to trace for the early time optical signals. The implications of neutrino physics on the expected detection are also discussed
Upper Limit on Gravitational Wave Backgrounds at 0.2 Hz with Torsion-bar Antenna
We present the first upper limit on gravitational wave (GW) backgrounds at an
unexplored frequency of 0.2 Hz using a torsion-bar antenna (TOBA). A TOBA was
proposed to search for low-frequency GWs. We have developed a small-scaled TOBA
and successfully found {\Omega}gw(f) < 4.3 \times 1017 at 0.2 Hz as
demonstration of the TOBA's capabilities, where {\Omega}gw (f) is the GW energy
density per logarithmic frequency interval in units of the closure density. Our
result is the first nonintegrated limit to bridge the gap between the LIGO band
(around 100 Hz) and the Cassini band (10-6 - 10-4 Hz).Comment: 4 pages, 5 figure