928 research outputs found
Reaction cross sections of the deformed halo nucleus 31Ne
Using the Glauber theory, we calculate reaction cross sections for the
deformed halo nucleus Ne. To this end, we assume that the Ne
nucleus takes the Ne + structure. In order to take into account the
rotational excitation of the core nucleus Ne, we employ the
particle-rotor model (PRM). We compare the results to those in the adiabatic
limit of PRM, that is, the Nilsson model, and show that the Nilsson model works
reasonably well for the reaction cross sections of Ne. We also
investigate the dependence of the reaction cross sections on the ground state
properties of Ne, such as the deformation parameter and the p-wave
component in the ground state wave function.Comment: 7 pages, 6 eps figure
Kiso observations for 20 GRBs in HETE-2 era
We have established a GRB follow-up observation system at Kiso observatory
(Japan) in 2001. Since the east Asian area had been blank for the GRB follow-up
observational network, this observational system is very important in studying
the temporal and spectral evolution of early afterglows. Using this system, we
have performed quick observations for optical afterglows from early phase based
on HETE-2 and INTEGRAL alerts. Thanks to the quick follow-up observation
system, we have been able to use the Kiso observatory in 20 events, and conduct
their follow-up observations in optical and near infrared wavelengths.Comment: 5 pages, 4 figure. Accepted for publication into "il nuovo cimento".
Proceeding of the 4th Rome GRB conference, eds. L. Piro, L. Amati, S. Covino,
B. Gendr
Very early multi-color observations of the plateau phase of GRB 041006 afterglow
Observations of the optical afterglow of GRB 041006 with the Kiso Observatory
1.05 m Schmidt telescope, the Lulin Observatory 1.0 m telescope and the
Xinglong Observatory 0.6 m telescope. Three-bands (B, V and R) of photometric
data points were obtained on 2004 October 6, 0.025-0.329 days after the burst.
These very early multi band light curves imply the existence of a color
dependent plateau phase. The B-band light curve shows a clear plateau at around
0.03 days after the burst. The R band light curve shows the hint of a plateau,
or a possible slope change, at around 0.1 days after the burst. The overall
behavior of these multi-band light curves may be interpreted in terms of the
sum of two separate components, one showing a monotonic decay the other
exhibiting a rising and a falling phase, as described by the standard afterglow
model.Comment: 11 pages, 2 figures, Accepted to ApJ Letter
The GRB 071112C: A Case Study of Different Mechanisms in X-ray and Optical Temporal Evolution
We present the study on GRB 071112C X-ray and optical light curves. In these
two wavelength ranges, we have found different temporal properties. The R-band
light curve showed an initial rise followed by a single power-law decay, while
the X-ray light curve was described by a single power-law decay plus a
flare-like feature. Our analysis shows that the observed temporal evolution
cannot be described by the external shock model in which the X-ray and optical
emission are produced by the same emission mechanism. No significant color
changes in multi-band light curves and a reasonable value of the initial
Lorentz factor ({\Gamma}0 = 275 \pm 20) in a uniform ISM support the afterglow
onset scenario as the correct interpretation for the early R-band rise. The
result suggests the optical flux is dominated by afterglow. Our further
investigations show that the X-ray flux could be created by an additional
feature related to energy injection and X-ray afterglow. Different theoretical
interpretations indicate the additional feature in X-ray can be explained by
either late internal dissipation or local inverse-Compton scattering in the
external shock.Comment: 20 pages, 3 figures, accepted for publication in Ap
- …