#6 Cosmic blasts. Several discoveries that GRBs conf ine their fiercest jets into nar. soon. NASAS Swin stlite, set for launch i this year lifted veils that had row beams, perhaps just I to 5 angular de-i mid-2004, should catch GRBs at five times grees across. Only some of these flares hap- the rate of any previous mission. It will tackle plosions in the universe: titanic blasts of en-i pen to point toward Earth, making them far ergy called gamma ray bursts (GRBs). Most more common in the universe than the num- the field's biggest remaining riddle: the ori- notably.In March, astronomers confirmed ber of sightings would suggest. One observa- gins of GRBs that last mere fractions of a the connection between GRBs and super- tion sowed some dissent, however: A claimed second. Today 's model with the most cachet novas the death throes of massive stars- detection of a polarized beam from a GRB involves the merger of two neutron stars when they spotted the unmistakable imprints sparked debate about whether the jets consist of a supernova in the glow of a bright GRB. almost entirely of highly organized electro- magnetic radiation, rather than a blast of par- 1. GRB 030329-SN 2003dh; More solid were the conclusions by sev- 2. High polarization of eral teams that an enigmatic set of lower- GRB021206 energy bursts, called x-ray flashes, streams from the same kinds of stellar catastrophes 3 X-ray flashes; that produce GRBs. Theorists think that4. Dark bursts GRBs Seen from the side. Other recent cok 5. Short bursts in the Swift i lapsing stars appeared to churn out narrow era cones of x-rays and wider sprays of matter that produced optical light and torrents of radio waves, but no gamma rays Teamwork was the key to these a vances. NASAs High Energy Transient Ex 200世界10 plorer overcame technical challenges to spot dozens of GRBs and x-ray flashes and beam their locations to ast roomers on the 大科敦成就 jets of gamma rays and fatter sprays seen in ground where a global network of robotic X-rays, optical light, and radio waves and traditional telescopes swung into action i This rapid detective work showed that a mysterious class of"dark"GRBs was visi- Astrophysicists now believe that the burst's ble in optical light after all, but only within ts of energy spewed into space when a star's minutes of the explosion core imploded, forming a black hole or-in a minority view-a rapidly spinning neutron star with a crushing magnetic field 2003. Science.302.2042-20432003, Science, 302, 2042-2043 1. GRB 030329 - SN 2003dh; 2. High polarization of GRB 021206; 3. X-ray flashes; 4. Dark bursts; 5. Short bursts in the Swift era. 2003年世界10 大科技成就