118440519
A systematic study on energy dependence of quasi-periodic oscillation frequency in GRS 1915+105
Systematically studying all the RXTE/PCA observations for GRS 1915+105 before November 2010, we have discovered three additional patterns in the relation between Quasi-Periodic Oscillation (QPO) frequency and photon energy, extending earlier outcomes reported by Qu et al. (Astrophys. J. 710:836, 2010). We have confirmed that as QPO frequency increases, the relation evolves from the negative correlation to positive one. The newly discovered patterns provide new constraints on the QPO models.
16433217
The afterglows of ultraluminous quasars
Quasars represent a brief phase in the life cycle of most massive galaxies, but the evolutionary connection between central black holes and their host galaxies remains unclear. While quasars are active and shining brighter than the Compton-limit luminosity, their radiation heats the surrounding medium to the Compton temperature, forming Compton spheres extending to the Stromgren radius of Fe26+/He2+. After the quasars shut off, their "afterglow" can be detected through three signatures: (1) an extended X-ray envelope, with a characteristic temperature of ~3 × 107 K, (2) Lyα and Lyβ lines and the K edge of Fe26+, and (3) nebulosity from hydrogen and helium recombination emission lines. We discuss the possibility of detecting these signatures using Chandra, the planned X-Ray Evolving Universe Spectroscopy mission, and ground-based optical telescopes. The luminosity and size of quasar afterglows can be used to constrain the lifetime of quasars.
17396076
INTEGRAL and RXTE/ASM observations on IGR J17098−3628
To probe further the possible nature of the unidentified source IGR J17098-3628, we have carried out a detailed analysis of its long-term time variability as monitored by RXTE/ASM, and of its hard X-ray properties as observed by INTEGRAL. INTEGRAL has monitored this sky region over years and significantly detected IGR J17098-3628 only when the source was in this dubbed active state. In particular, at $\ge$ 20 keV, IBIS/ISGRI caught an outburst in March 2005, lasting for $\sim$5 days with detection significance of 73$\sigma$ (20-40 keV) and with the emission at $ $20 keV) outburst by $\sim$2 days. This resembles the behavior of X-ray novae like XN 1124-683, hence it further suggests a LMXB nature for IGR J17098-3628. While the quality of the ASM data prevents us from drawing any definite conclusions, these discoveries are important clues that, coupled with future observations, will help to resolve the as yet unknown nature of IGR J17098-3628.
119102309
Possible hard X-ray shortages in bursts from KS 1731-260 and 4U 1705-44
Aims. A hard X-ray shortage, implying the cooling of the corona, was observed during bursts of IGR J17473-272, 4U 1636-536, Aql X-1, and GS 1826-238. Apart from these four sources, we investigate here an atoll sample, in which the number of bursts for each source is larger than 5, to explore the possible additional hard X-ray shortage during Rossi X-ray timing explorer (RXTE) era. Methods. According to the source catalog that shows type-I bursts, we analyzed all the available pointing observations of these sources carried out by the RXTE proportional counter array. We grouped and combined the bursts according to their outburst states and searched for the possible hard X-ray shortage while bursting. Results. We found that the island states of KS 1731-260 and 4U 1705-44 show a hard X-ray shortage at significant levels of 4.5 and 4.7σ and a systematic time lag of 0.9 ± 2.1 s and 2.5 ± 2.0 s with respect to the soft X-rays, respectively. While in their banana branches and other sources, we did not find any consistent shortage.
17406200
EVOLUTION OF GASEOUS DISK VISCOSITY DRIVEN BY SUPERNOVA EXPLOSIONS IN STAR-FORMING GALAXIES AT HIGH REDSHIFT
Motivated by Genzel et al.'s observations of high-redshift star-forming galaxies, containing clumpy and turbulent rings or disks, we build a set of equations describing the dynamical evolution of gaseous disks with inclusion of star formation and its feedback. Transport of angular momentum is due to "turbulent" viscosity induced by supernova explosions in the star formation region. Analytical solutions of the equations are found for the initial cases of a gaseous ring and the integrated form for a gaseous disk, respectively. For a ring with enough low viscosity, it evolves in a slow process of gaseous diffusion and star formation near the initial radius. For a high viscosity, the ring rapidly diffuses in the early phase. The diffusion drives the ring into a region with a low viscosity and starts the second phase undergoing pile-up of gas at a radius following the decreased viscosity torque. The third is a sharply decreasing phase because of star formation consumption of gas and efficient transportation of gas inward forming a stellar disk. We apply the model to two z similar to 2 galaxies BX 482 and BzK 6004, and find that they are undergoing a decline in their star formation activity.
15715110
Suppressed star formation in circumnuclear regions in seyfert galaxies
Feedback from black hole activity is widely believed to play a key role in regulating star formation and black hole growth. A long-standing issue is the relation between star formation and the fueling of the supermassive black holes in active galactic nuclei (AGNs). We compile a sample of 57 Seyfert galaxies to tackle this issue. We estimate the surface densities of gas and star formation rates in circumnuclear regions (CNRs). Comparing them with the well-known Kennicutt-Schmidt (K-S) law, we find that the star formation rates (SFRs) in the CNRs of most Seyfert galaxies are suppressed in this sample. Feedback is suggested to explain the suppressed SFRs.
119220684
Search for the Signal of Monotop Production at the Early LHC
The main tasks of the LHC are to answer the fundamental questions in particle physics: whether the Higgs boson exist or not; are there new physics beyond the SM such as supersymmetry (SUSY), extra dimension, etc., at the TeV scale? The first stage of the LHC has discovered a scalar resonance closely resembling the SM Higgs boson, but provides no clue on the new physics beyond the SM.
122859923
Spectral relation between X-rays and gamma rays for blazar high-energy emission
We collect 10 active galactic nuclei with both X-ray and gamma-ray spectral data. A correlation is found between X-ray and gamma-ray spectral indices. Possible constraints on existing models for gamma-ray emission are discussed. A new model involving inverse-Compton scattering of beamed relativistic electrons in the full cross section is outlined to account for this spectral relation.
119204233
Search for new physics in events with same-sign dileptons and b-tagged jets in pp collisions at $ \sqrt {s} = 7 $ TeV
A bstractA search for new physics is performed using isolated same-sign dileptons with at least two b-quark jets in the final state. Results are based on a 4.98 fb−1 sample of proton-proton collisions at a centre-of-mass energy of 7 TeV collected by the CMS detector. No excess above the standard model background is observed. Upper limits at 95% confidence level are set on the number of events from non-standard-model sources. These limits are used to set constraints on a number of new physics models. Information on acceptance and efficiencies are also provided so that the results can be used to confront additional models in an approximate way.
110044657
Development of the X-band RF power source for JLC
In this paper, we summarize our activities on X-band RF power source development for the Japan Linear Collider (JLC) project. First, we have designed and tested a solenoid-focused klystron at 11.424 GHz with a pulse length of 1.5 /spl mu/s and with an efficiency of 47%. A periodic permanent magnet (PPM) klystron, the first in that kind at KEK, is also under development. In parallel to this activity, another PPM klystron has been developed and remodeled in collaboration with BINP. Second, a new RF window with 100-MW power-handling capability has been designed and tested. It utilizes the TW mixed mode (TE11 and TM11 modes) to reduce the surface field at the brazing edge of the ceramic. The cold model test shows a low electric field at the brazing point as predicted by HFSS calculations. The high power model is now in manufacturing and the testing will start soon. Third, the Blumlein modulator was upgraded to produce a pulse with 2 /spl mu/s flat top and 200 ns rise time at 550 kV output voltage. Fourth, the multi-mode 2/spl times/2 DLDS (Delay Line Distribution System) pulse compression system has been designed, and its basic unit was manufactured and tested for proof of the principle. The measurement results show that the system works well with a high power distribution efficiency. The so-called mode stability experiment is also under preparation in the ATF linac tunnel in collaboration with SLAC. This experiment is aimed for examination of the stability of linearly polarized TE12 mode in a 55 m long waveguide, a key issue in the present configuration of multi-mode DLDS. Details of these developments and measurement results are presented.
122789554
Observation of B ---> D(*) K- K0(*) decays
Abstract The B→D (∗) K − K (∗)0 decays have been observed for the first time. The branching fractions of the B→D (∗) K − K (∗)0 decay modes are measured. Significant signals are found for the B→D (∗) K − K ∗0 and B−→D0K−K0S decay modes. The invariant mass and polarization distributions for the K − K ∗0 and K−K0S subsystems have been studied. For the K − K ∗0 sybsystem these distributions agree well with those expected for two-body B→D (∗) a 1 − (1260) decays, with a 1 − (1260)→K − K ∗0 . The analysis was done using 29.4 fb−1 of data collected with the Belle detector at the e+e− asymmetric collider KEKB.