5,721 research outputs found
Color Behavior Of BL Lacertae Object OJ 287 During Optical Outburst
This paper aims to study the color behavior of the BL Lac object OJ 287
during optical outburst. According to the revisit of the data from the OJ-94
monitoring project and the analysis the data obtained with the 60/90 cm Schmidt
Telescope of NAOC, we found a bluer-when-brighter chromatism in this object.
The amplitude of variation tends to decrease with the decrease of frequency.
These results are consistent with the shock-in-jet model. We made some
simulations and confirmed that both amplitude difference and time delay between
variations at different wavelengths can result in the phenomenon of
bluer-when-brighter. Our observations confirmed that OJ 287 underwent a
double-peaked outburst after about 12 years from 1996, which provides further
evidence for the binary black hole model in this object.Comment: 25 pages, 13 figure
Associated production of the top-pions and single top at hadron colliders
In the context of topcolor assisted technicolor(TC2) models, we study the
production of the top-pions with single top quark via the
processes and ,
and discuss the possibility of detecting these new particles at Tevatron and
LHC. We find that it is very difficult to observe the signals of these
particles via these processes at Tevatron, while the neutral and charged
top-pions and can be detecting via considering
the same sign top pair event and the (or )
event at LHC, respectively.Comment: latex files,14 pages, 7 figures. Accepted for publication in Phys.
Rev.
Precision cosmology from future lensed gravitational wave and electromagnetic signals
The standard siren approach of gravitational wave cosmology appeals to the
direct luminosity distance estimation through the waveform signals from
inspiralling double compact binaries, especially those with electromagnetic
counterparts providing redshifts. It is limited by the calibration
uncertainties in strain amplitude and relies on the fine details of the
waveform. The Einstein Telescope is expected to produce
gravitational wave detections per year, of which will be lensed. Here
we report a waveform-independent strategy to achieve precise cosmography by
combining the accurately measured time delays from strongly lensed
gravitational wave signals with the images and redshifts observed in the
electromagnetic domain. We demonstrate that just 10 such systems can provide a
Hubble constant uncertainty of for a flat Lambda Cold Dark Matter
universe in the era of third generation ground-based detectors
- …