The redshift and the blueshift of spectral lines and the motion of mass-points in gravitational fields of photon stars

The redshift and the blueshift of spectral lines in gravitational fields of photon stars are studied when the observing and emitting points of the spectral lines locate at different positions. And the motion of masspoints is also studied. The studies show that the redshift and the blueshift of spectral lines in gravitational fields of photon stars can he arbitrarily positive, and the motion of mass-points in gravitational fields of photon stars can be used to determine the mass of photon stars.

Butterfly distribution of Earth＇s radiation belt relativistic electrons induced by dayside chorus

Previous theoretical studies have shown that dayside chorus can produce butterfly distribution of energetic electrons in the Earth＇s radiation belts by preferentially accelerating medium pitch angle electrons, but this requires the further confirmation from high- resolution satellite observation. Here, we report correlated Van Allen Probes data on wave and particle during the 1 I-13 April, 2014 geomagnetic storm. We find that a butterfly pitch angle distribution of relativistic electrons is formed around the location L = 4.52, corresponding to the presence of enhanced dayside chorus. Using a Gaussian distribution fit to the observed chorus spectra, we calculate the bounce-averaged diffusion rates and solve two-dimensional Fokker-Planck equation. Numerical results demonstrate that acceleration by dayside chorus can yield the electron flux evolution both in the energy and butterfly pitch angle distribution comparable to the observation, providing a further evidence for the formation of butterfly distribution of relativistic electrons driven by very low frequency （VLF） plasma waves.

Explanations of the DAMPE high energy electron/positron spectrum in the dark matter annihilation and pulsar scenarios

Many studies have shown that either the nearby astrophysical source or dark matter （DM） annihilation/decay can be used to explain the excess of high energy cosmic ray （CR） e^±which is detected by many experiments, such as PAMELA and AMS-02. Recently, the dark matter particle explorer （DAMPE） collaboration has reported its first result of the total CR e^± spectrum from 25 GeV to 4.6TeV with high precision. In this work, we study the DM annihilation and pulsar interpretations of this result. We show that the leptonic DM annihilation channels to r＋＇/＂-, 4p, 4＂/＇, and mixed charged lepton final states can well explain the DAMPE e^± spectrum. We also find that the mixed charged leptons channel would lead to a sharp drop structure at - TeV. However, the ordinary DM explanations have been almost excluded by the constraints from the observations of gamma-ray and CMB, unless some exotic DM models are introduced. In the pulsar scenario, we analyze 21 nearby known pulsars and assume that one of them dominantly contributes to the high energy CR e^± spectrum. Involving the constraint from the Fermi-LAT observation of the e^± anisotropy, we find that two pulsars could explain the DAMPE e^± spectrum. Our results show that it is difficult to discriminate between the DM annihilation and single pulsar explanations of high energy e^± with the current DAMPE result.

Can FSRQs produce the Ice Cube detected diffuse neutrino emission?

IceCube has reported the detection of a diffuse TeV-PeV neutrino emission, for which the flat spectrum radio quasars （FSRQs） have been proposed to be the candidate sources. Here we assume that the neutrino flux from FSRQs is proportional to their gamma-ray ones, and obtain the gamma-ray/neutrino flux ratio by the diffuse gamma-ray flux from Fermi-LAT measurement of FSRQs and the diffuse neutrino flux detected by IceCube. We apply this ratio to individual FSRQs and hence predict their neutrino flux. We find that a large fraction of candidate FSRQs from the northern sky in the IceCube point source search has predicted neutrino flux above the IceCube upper limit; and for the sample of stacking search for neutrinos by IceCube, the predicted stacked flux is even larger than the upper limit of stacked flux by orders of magnitude. Therefore the IceCube limit from stacking searches, combined with the Fermi-LAT observations, already rejects FSRQs as the main sources of IceCube-detected diffuse neutrinos： FSRQs can only account for 〈 10% 〈 4%） of the IceCube-detected diffuse neutrino flux, according to the stacking searches from the whole （northern） sky. The derived small neutrino/gamma-ray flux ratio also implies that the gamma-ray emission from FSRQs cannot be produced by the secondary le^tons and photons from the Non nroduction nrocesses. The caveat in the assumntions is discussed.

Synthesis and photovoltaic properties of a star-shaped molecule based on a triphenylamine core and branched terthiophene end groups

A new star-shaped donor-acceptor molecule has been synthesized for application as the donor material in solution-processed bulk-heterojunction organic solar cells (OSCs). The molecule consists of a triphenylamine (TPA) unit as the core and a donor unit with three arms containing benzo[1,2,5]thiadiazole (BT) acceptor units and 5,5''-dihexyl-2,2′:3′,2″-terthiophene (tTh) end groups. The molecule, denoted S(TPA-BT-tTh), exhibits a broad absorption band in the wavelength range 300-650 nm and high hole mobility of 1.1×10 -4 cm2 V -1 s 1 . An OSC device based on S(TPA-BT-tTh) as donor and [6,6]-phenyl C71 -butyric acid methyl ester (PC 70 BM) as the acceptor (1:3, w/w) exhibited a power conversion efficiency of 2.28% with a short circuit current density of 6.39 mA/cm2 under illumination of AM.1.5, 100 mW/cm2 .