635 research outputs found
The unique rapid variabilities of the iron K line profiles in NGC 4151
We present a detailed analysis of the iron K line variabilities in
NGC 4151 by using long ASCA observation data obtained in May 1995. Despite the
relatively small amplitude variations in the continuum flux, the iron K
line flux and profile show dramatic variations. Particularly, the line profile
changes from single peak to seeming double peaks and back in time scales of a
few 10 sec. The seemingly double-peaked profiles can be well interpreted as
line emission from a Keplerian ring around a massive black hole. An absorption
line at around 5.9 keV is also marginnaly detected. We discussed current Fe K
line models, but none of them can well explain the observed line and continuum
variations.Comment: 18 pages, latex, 3 figures, ApJ accepte
(3R*)-Methyl 3-[(2S*)-4,6-dimethoxy-2-(4-methoxyphenyl)-3-oxo-2,3-dihydro-1-benzofuran-2-yl]-2-methoxycarbonyl-3-phenylpropionate
The title compound, C29H28O9, was isolated from the reaction of 4,6-dimethoxy-2-(4-methoxyphenyl)-3-benzofuran and α-methoxycarbonylcinnaminate. The two aromatic rings form a dihedral angle of 22.7 (1)°. One methoxycarbonyl group is disordered between two orientations in a 0.612 (4):0.388 (4) ratio. The crystal structure exhibits no significantly short intermolecular contacts
Evidence for a population of beamed radio intermediate quasars
Whether radio intermediate quasars possess relativistic jets as radio-loud
quasars is an important issue in the understanding of the origin of radio
emission in quasars. In this letter, using the two-epoch radio data obtained
during Faint Image of Radio Sky at Twenty centimeter sky (FIRST) and NOAO VLA
Sky Survey (NVSS), we identify 89 radio variable sources in the Sloan Digital
Sky Survey. Among them, more than half are radio intermediate quasars
(RL=f2cm/f2500A<250). For all objects with available multiple band radio
observations, the radio spectra are either flat or inverted. The brightness
temperature inferred from the variability is larger than the synchrotron-self
Compton limit for a stationary source in 87 objects, indicating of relativistic
beaming. Considering the sample selection and viewing angle effect, we conclude
that relativistic jets probably exist in a substantianl fraction of radio
intermediate quasars.Comment: 15 pages, 4 figures, 1 table, Accepted to the Astrophysical Journa
Enhancement of baryon-to-meson ratios around jets as a signature of medium response
We present a unique signal of jet-induced medium excitations: the enhancement
of baryon-to-meson ratios around the quenched jets. To illustrate this, we
study jet-particle correlations and the distributions of jet-induced identified
particles with respect to the jet direction in Pb+Pb collisions at the LHC via
a multi-phase transport model. We find a strong enhancement of baryon-to-meson
ratios for associated particles at intermediate transverse momentum around the
triggered jets in Pb+Pb collisions relative to p+p collisions, due to the
coalescence of jet-excited medium partons. Since the lost energy from jets can
diffuse to large angles, such baryon-to-meson-ratio enhancement is more
pronounced for larger relative distance from the jet axis. We argue that the
experimental confirmation of the enhancement of jet-induced baryon-to-meson
ratios around the jets will provide an unambiguous evidence for the medium
response to jet quenching in heavy-ion collisions.Comment: 6 pages, 3 figure
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