QUASI-PERIODIC VARIATIONS IN X-RAY EMISSION AND LONG-TERM RADIO OBSERVATIONS: EVIDENCE FOR A TWO-COMPONENT JET IN Sw J1644+57

The continued observations of Sw J1644+57 in X-ray and radio bands accumulated a rich data set to study the relativistic jet launched in this tidal disruption event. The X-ray light curve of Sw J1644+57 from 5-30 days presents two kinds of quasi=periodic variations: a 200 s quasi=periodic oscillation (QPO) and a 2.7 day quasi=periodic variation. The latter has been interpreted by a precessing jet launched near the Bardeen-Petterson radius of a warped disk. Here we suggest that the similar to 200 s QPO could be associated with a second, narrower jet sweeping the observer line-of-sight periodically, which is launched from a spinning black hole in the misaligned direction with respect to the black hole's angular momentum. In addition, we show that this two-component jet model can interpret the radio light curve of the event, especially the re-brightening feature starting similar to 100 days after the trigger. From the data we infer that inner jet may have a Lorentz factor of Gamma(j) similar to 5.5 and a kinetic energy of E-k,E-iso similar to 3.0 x 10(52) erg, while the outer jet may have a Lorentz factor of Gamma(j) similar to 2.5 and a kinetic energy of E-k,E-iso similar to 3.0 x 10(53) erg.Astronomy & AstrophysicsSCI(E)3ARTICLEleiwh@hust.edu.cn; dxwang@hust.edu.cn; zouyc@hust.edu.cn; zhang@physics.unlv.edu1null78