5,331 research outputs found
Aspherical supernova explosions and formation of compact black hole low-mass X-ray binaries
It has been suggested that black-hole low-mass X-ray binaries (BHLMXBs) with
short orbital periods may have evolved from BH binaries with an
intermediate-mass secondary, but the donor star seems to always have higher
effective temperatures than measured in BHLMXBs (Justham, Rappaport &
Podsiadlowski 2006). Here we suggest that the secondary star is originally an
intermediate-mass (\sim 2-5 M_{\sun}) star, which loses a large fraction of
its mass due to the ejecta impact during the aspherical SN explosion that
produced the BH. The resulted secondary star could be of low-mass (\la 1
M_{\sun}). Magnetic braking would shrink the binary orbit, drive mass transfer
between the donor and the BH, producing a compact BHLMXB.Comment: 4 pages, accepted for publication in MNRAS Letter
Pulse-shape discrimination between electron and nuclear recoils in a NaI(Tl) crystal
We report on the response of a high light-output NaI(Tl) crystal to nuclear
recoils induced by neutrons from an Am-Be source and compare the results with
the response to electron recoils produced by Compton scattered 662 keV
-rays from a Cs source. The measured pulse-shape discrimination
(PSD) power of the NaI(Tl) crystal is found to be significantly improved
because of the high light output of the NaI(Tl) detector. We quantify the PSD
power with a quality factor and estimate the sensitivity to the interaction
rate for weakly interacting massive particles (WIMPs) with nucleons, and the
result is compared with the annual modulation amplitude observed by the
DAMA/LIBRA experiment. The sensitivity to spin-independent WIMP-nucleon
interactions based on 100 kgyear of data from NaI detectors is estimated
with simulated experiments, using the standard halo model.Comment: 11page
Optical and infrared observations of the Type IIP SN2002hh from day 3 to 397
We present optical and infrared (IR) observations of the type IIP SN2002hh
from 3 to 397 days after explosion. The optical spectroscopic (4-397d) and
photometric (3-278d) data are complemented by spectroscopic (137-381d) and
photometric (137-314d) data acquired at IR wavelengths. This is the first time
L-band spectra have ever been successfully obtained for a supernova at a
distance beyond the Local Group. The VRI light curves in the first 40 days
reveal SN2002hh to be a SN IIP (plateau) - the most common of all core-collapse
supernovae. SN2002hh is one of the most highly extinguished supernovae ever
investigated. To provide a good match between its early-time spectrum and a
coeval spectrum of the Type IIP SN1999em, as well as maintaining consistency
with KI interstellar absorption, we invoke a 2-component extinction model. One
component is due to the combined effect of the interstellar medium of our Milky
Way Galaxy and the SN host galaxy, while the other component is due to a "dust
pocket" where the grains have a mean size smaller than in the interstellar
medium. The early-time optical light curves of SNe 1999em and 2002hh are
generally well-matched, as are the radioactive tails of these two SNe and
SN1987A. The late-time similarity of the SN2002hh optical light curves to those
of SN1987A, together with measurements of the optical/IR luminosity and [FeII]
1.257mu emission indicate that 0.07 +- 0.02 Msun of Ni 56 was ejected by
SN2002hh. [... ABRIDGED...] From the [OI] 6300,6364 A doublet luminosity we
infer a 16-18 Msun main-sequence progenitor star. The progenitor of SN2002hh
was probably a red supergiant with a substantial, dusty wind.Comment: 32 pages, 30 figures, accepted for publication in MNRA
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