Qiu-He Peng

The physics of strong magnetic fields in neutron stars

In this paper we present a new result, namely that the primal magnetic field of the collapsed core during a supernova explosion will, as a result of the conservation of magnetic flux, receive a massive boost to more than 90 times its original value by the Pauli paramagnetization of the highly degenerate relativistic electron gas just after the formation of the neutron star. Thus, the observed super-strong magnetic field of neutron stars may originate from the induced Pauli paramagnetization of the highly degenerate relativistic electron gas in the interior of the neutron star. We therefore have an apparently natural explanation for the surface magnetic field of a neutron star.

Magnetic field decay of magnetars in supernova remnants

In this paper, we modify our previous research carefully, derive a new expression of electron energy density in superhigh magnetic fields. Based on our improved model, we re-compute the electron capture rates and the magnetic fields’ evolutionary timescales t of magnetars. According to the calculated results, the superhigh magnetic fields may evolve on timescales ∼ (106−107) yrs for common magnetars, and the maximum timescale of the field decay, t ≈ 2.9507× 10 yrs, corresponding to an initial internal magnetic field B0 = 3.0×1015 G and an initial temperature T0 = 2.6×108 K. Motivated by the results of the neutron star-supernova remnant(SNR) association of Zhang & Xie(2011), we calculate the maximum B0 of magnetar progenitors, Bmax ∼ (2.0×1014−2.93×1015) G when T0 = 2.6×108 K. When T0 ∼ 2.75×108− 1.75×108 K, the maximum B0 will also be in the range of ∼ 10 − 10 G, not exceeding the upper limit of magnetic field of a mag-

New Estimates of the Inclination, Position Angle, Pitch Angle, and Scale Height of the Whirlpool Galaxy

The inclination (i) and position angle (PA) of the Whirlpool galaxy (M51) are critical to modeling and interpreting observations. Here we make improved estimates of these parameters by fitting logarithmic spirals to the main arms. From separate fits to each major arm, we obtain i = 203 ± 28 and PA = 120 ± 25. We then use Poissons equation for the logarithmic perturbation of the density to estimate the mean vertical scale height (H) of M51 to be 95-178 pc.

Determination of the Thickness of Non-Edge-on Disk Galaxies

We propose a method to determine the thickness of non-edge-on disk galaxies from their observed structure of spiral arms, based on the solution of the truly three-dimensional Poissons equation for a logarithmic disturbance of density and under the condition where the self-consistency of the density wave theory is no longer valid. From their measured number of arms, pitch angle and location of the innermost point of the spiral arms, we derive and present the thicknesses of 34 spiral galaxies.

The Origin of Magnetars?The Role of Anisotropic neutron superfluid of Neutron Stars

We estimate the strength of the induced magnetic field due to the Pauli paramagnetic moment of the 3P2 Cooper pairs for the anisotropic (3P2) neutron superfluid under the applied magnetic field (B0) in neutron stars. The induced magnetic field of the anisotropic (3P2) neutron superfluid is as follows. B(in)?(1.9/T7)?B0 (T7 denotes the interior temperature of the neutron star in unit of 107 K), ? = (m(3P2)/0.1?M?)RNS,6?3. The induced magnetic field will gradually increase with the temperature of the neutron star decreasing in their late evolutionary stage. A magnetar may appear in a condition when T7<<?. The upper limit of the magnetic field for the magnetars is Bmax(in)(3P2)?2.02?1014?.

Elliptical Galaxies with Emission Lines from the Sloan Digital Sky Survey

As part of a study of star formation history along the Hubble sequence, we present here the results for 11 elliptical galaxies with strong nebular emission lines. After removing the dilution from the underlying old stellar populations by use of stellar population synthesis model, we derive the accurate fluxes of all the emission lines in these objects, which are then classified, using emission line ratios, into one Seyfert 2, six LINERs and four HII galaxies. We also identify one HII galaxy (A1216+04) as a hitherto unknown Wolf-Rayet galaxy from the presence of the Wolf-Rayet broad bump at 4650 A. We propose that the star-forming activities in elliptical galaxies are triggered by either galaxy-galaxy interaction or the merging of a small satellite/a massive star cluster, as has been suggested by recent numerical simulations.

Photometry and Spectroscopy of KS Ursae Majoris during Superoutburst

We report photometric and spectroscopic observations of the SU UMa - type dwarf nova KS Ursae Majoris during its 2003 February superoutburst. Modulations with a period of 0. 07017 +/- 0. 00021 days, which is 3.3% larger than the orbital period, have been found during the superoutburst and may be positive superhumps. A maximum trough- to-peak amplitude of around 0.3 mag is determined for this superhump. The spectra show broad absorption- line profiles. The lines display blue and red troughs that alternate in depth. The radial velocity curve of the absorption wings of H beta has an amplitude of 40 +/- 11 km s (-1) and a phase offset of 0. 12 +/- 0. 03. The gamma- velocity of the binary is 3 +/- 9 km s (-1) and varies on the order of 50 km s (-1) from day to day. From other clear evidence for a precessing eccentric disk, we obtain a solution to an eccentric outer disk consistent with theoretical works, which demonstrates the validity of the relation between superhumps and tidal effects. The inner part of the disk is also eccentric, as evidenced by asymmetric and symmetric wings in the lines. Therefore, the whole disk is eccentric, and the variation of the gamma- velocity and the evolutionary asymmetric line profiles could be criteria for a precessing eccentric accretion disk.

Superhumps behavior during normal outbursts in ER Ursae Majoris: Spectroscopy and photometry

We undertook a 4-day spectroscopic observation and conducted a 13-day photometric study of an SU UMa-type dwarf nova, ER Ursae Majoris. The mean K-amplitude for the emission lines is 54 +/- 8 kms(-1) and the gamma velocity is 8 +/- 4 km s(-1) based on our spectroscopic results. A phase shift of 0.22 was also obtained. Our photometric observation confirms superhumps in normal outbursts of ER UMa. and reconciles contradictory observational results obtained by different authors. We find that superhumps possibly develop near each normal outburst maximum and fade out before the next Outburst maximum. If the observed humps were not late superhunips, but ordinary superhumps, much more theoretical work should be done to explain the new phenomena.

The Origin of Glitches in Pulsars — Phase Oscillation between Anisotropic Superfluid and Normal State of Neutrons in Neutron Stars

Considering neutron star heating by magnetic dipole radiation from 3PF2 superfluid neutron vortices inside the star, we propose a neutron phase oscillation model between the normal neutron Fermi fluid and the 3PF2 superfluid neutron vortices at the transition temperature of Ttrans = (2−3)×108 K. With this model we can qualitatively explain most of the observations on pulsar glitches up to date.

Is the energy generation rate of nuclear reactions in hot accretion flows important

The temperature of hot accretion flows around black holes is sufficiently high for the ignition of nuclear reactions. This is potentially an important nucleosynthesis mechanism in the universe. As the first step in studying this problem, we need to measure physical quantities such as density and temperature of the accretion flow. In usual studies of the hot accretion flow, viscous dissipation is considered to be the only heating mechanism, while the heating caused by nuclear reactions is not considered. In this paper, we investigate whether the energy generation rate of nuclear reaction is important compared to the viscous heating. Our calculation indicates that the former is at most one percent of the latter and thus is not important. The dynamics of accretion flow can be therefore calculated in the usual way, without the need to consider heating due to nuclear reactions.