1,604 research outputs found
Unveiling GRB hard X-ray afterglow emission with Simbol-X
Despite the enormous progress occurred in the last 10 years, the Gamma-Ray
Bursts (GRB) phenomenon is still far to be fully understood. One of the most
important open issues that have still to be settled is the afterglow emission
above 10 keV, which is almost completely unexplored. This is due to the lack of
sensitive enough detectors operating in this energy band. The only detection,
by the BeppoSAX/PDS instrument (15-200 keV), of hard X-ray emission from a GRB
(the very bright GRB 990123), combined with optical and radio observations,
seriously challenged the standard scenario in which the dominant mechanism is
synchrotron radiation produced in the shock of a ultra-relativistic fireball
with the ISM, showing the need of a substantial revision of present models. In
this respect, thanks to its unprecedented sensitivity in the 10-80 keV energy
band, Simbol-X, through follow-up observations of bright GRBs detected and
localized by GRB dedicated experiments that will fly in the >2010 time frame,
will provide an important breakthrough in the GRB field.Comment: 4 pages, 2 figures. Paper presented at "Simbol-X: the hard X-ray
universe in focus", held in Bologna, Italy, on 14-16 May 2007. To be
published in Memorie della Societa' Astronomica Italian
The X-ray afterglow of GRB980519
Over a total of 20 gamma-ray bursts localized with arcmin accuracies,
GRB980519 represents the 13th detected by the BeppoSAX Wide Field Cameras. An
X-ray TOO observation performed by the BeppoSAX Narrow Field Instruments,
starting about 9.5 hours after the high energy event, revealed X-ray afterglow
emission in the 0.1--10 keV energy range. The flux decay was particularly fast
with a power-law index of ~ 1.8. This is the fastest decay so far measured.
Signs of bursting activity are evident. The power-law spectral index of 2.8
(+0.6, -0.5) is quite soft but not unique among GRB afterglows.Comment: 2 pages; 3 EPS figures; requires aa.cls, psfig.sty; accepted for
publication on A&AS (Proc. of ``Gamma-Ray Bursts in the Afterglow Era'', Rome
3-6 Nov. 1998.
A Family History of Lethal Prostate Cancer and Risk of Aggressive Prostate Cancer in Patients Undergoing Radical Prostatectomy.
We investigated whether a family history of lethal prostate cancer (PCa) was associated with high-risk disease or biochemical recurrence in patients undergoing radical prostatectomy. A cohort of radical prostatectomy patients was stratified into men with no family history of PCa (NFH); a first-degree relative with PCa (FH); and those with a first-degree relative who had died of PCa (FHD). Demographic, operative and pathologic outcomes were analyzed. Freedom from biochemical recurrence was examined using Kaplan-Meier log rank. A multivariate Cox logistic regression analysis was also performed. We analyzed 471 men who underwent radical prostatectomy at our institution with known family history. The three groups had: 355 patients (75%) in NFH; 97 patients (21%) in FH; and 19 patients (4%) in FHD. The prevalence of a Gleason score ≥8, higher pathologic T stage, and biochemical recurrence (BCR) rates did not significantly differ between groups. On Kaplan-Meier analysis there were no differences in short-term BCR rates (p = 0.212). In this cohort of patients undergoing radical prostatectomy, those with first-degree relatives who died of PCa did not have an increased likelihood of high-risk or aggressive PCa or shorter-term risk of BCR than those who did not
- …