Nucleosynthesis in Core-Collapse Supernovae and GRB--Metal-Poor Star Connection

We review the nucleosynthesis yields of core-collapse supernovae (SNe) for various stellar masses, explosion energies, and metallicities. Comparison with the abundance patterns of metal-poor stars provides excellent opportunities to test the explosion models and their nucleosynthesis. We show that the abundance patterns of extremely metal-poor (EMP) stars, e.g., the excess of C, Co, Zn relative to Fe, are in better agreement with the yields of hyper-energetic explosions (Hypernovae, HNe) rather than normal supernovae. We note that the variation of the abundance patterns of EMP stars are related to the diversity of the Supernova-GRB connection. We summarize the diverse properties of (1) GRB-SNe, (2) Non-GRB HNe/SNe, (3) XRF-SN, and (4) Non-SN GRB. In particular, the Non-SN GRBs (dark hypernovae) have been predicted in order to explain the origin of C-rich EMP stars. We show that these variations and the connection can be modeled in a unified manner with the explosions induced by relativistic jets. Finally, we examine whether the most luminous supernova 2006gy can be consistently explained with the pair-instability supernova model.Comment: 15 pages, 9 figures. To appear in "Supernova 1987A: 20 Years After: Supernovae and Gamma-Ray Bursters", eds. S. Immler, K. Weiler, & R. McCray (American Institute of Physics) (2007

Detection of Pre-Shock Dense Circumstellar Material of SN 1978K

The supernova SN 1978K has been noted for its lack of emission lines broader than a few thousand km/s since its discovery in 1990. Modeling of the radio spectrum of the peculiar SN 1978K indicates the existence of HII absorption along the line of sight. To determine the nature of this absorbing region, we have obtained a high-dispersion spectrum of SN 1978K at the wavelength range 6530--6610 \AA. The spectrum shows not only the moderately broad H-alpha emission of the supernova ejecta but also narrow nebular H-alpha and [N II] emission. The high [N II]6583/H-alpha ratio, 0.8-1.3, suggests that this radio absorbing region is a stellar ejecta nebula. The expansion velocity and emission measure of the nebula are consistent with those seen in ejecta nebulae of luminous blue variables. Previous low-dispersion spectra have detected a strong [N II]5755 line, indicating an electron density of 3-12x10^5 cm^{-3}. We argue that this stellar ejecta nebula is probably part of the pre-shock dense circumstellar envelope of SN 1978K. We further suggest that SN 1997ab may represent a young version of SN 1978K.Comment: 12 pages, 1 figure, accepted for publication in the ApJ Letter

Radio Spectral Index and Expansion of 3C58

We present new observations of the plerionic supernova remnant 3C58 with the VLA at 74 and 327 MHz. In addition, we re-reduced earlier observations at 1.4 and 4.9 GHz taken in 1973 and 1984. Comparing these various images, we find that: 1. the remnant has a flat and relatively uniform spectral index distribution, 2. any expansion of the remnant with time is significantly less than that expected for uniform, undecelerated expansion since the generally accepted explosion date in 1181 A.D., and 3. there is no evidence for a non-thermal synchrotron emission shell generated by a supernova shock wave, with any such emission having a surface brightness of <1 x 10^(-21) W / (m^2 Hz sr) at 327 MHz.Comment: 18 pages, 7 Figures, Latex, Accepted for publication in the Astrophysical Journa

VLBI observations of SN 2008iz: I. Expansion velocity and limits on anisotropic expansion

We present observations of the recently discovered supernova 2008iz in M82 with the VLBI High Sensitivity Array at 22 GHz, the Very Large Array at frequencies of 1.4, 4.8, 8.4, 22 and 43 GHz, and the Chandra X-ray observatory. The supernova was clearly detected on two VLBI images, separated by 11 months. The source shows a ring-like morphology and expands with a velocity of ~23000 km/s. The most likely explosion date is in mid February 2008. The measured expansion speed is a factor of ~2 higher than expected under the assumption that synchrotron self-absorption dominates the light curve at the peak, indicating that this absorption mechanism may not be important for the radio emission. We find no evidence for an asymmetric explosion. The VLA spectrum shows a broken power law, indicating that the source was still optically thick at 1.4 GHz in April 2009. Finally, we report upper limits on the X-ray emission from SN 2008iz and a second radio transient recently discovered by MERLIN observations.Comment: accepted Astronomy & Astrophysics, 9 pages, 8 figures, also available at http://www.mpifr-bonn.mpg.de/staff/abrunthaler/pub.shtm

Determination of absolute neutrino masses from Z-bursts

Ultrahigh energy neutrinos (UHE\nu) scatter on relic neutrinos (R\nu) producing Z bosons, which can decay hadronically producing protons (Z-burst). We compare the predicted proton spectrum with the observed ultrahigh energy cosmic ray (UHECR) spectrum and determine the mass of the heaviest R\nu via a maximum likelihood analysis. Our prediction depends on the origin of the power-like part of the UHECR spectrum: m_\nu=2.75^{+1.28}_{-0.97} eV for Galactic halo and 0.26^{+0.20}_{-0.14} eV for extragalactic (EG) origin. The necessary UHE\nu flux should be detected in the near future.Comment: slight rewording, revised neutrino fluxes, conclusions unchanged, version to appear in Phys. Rev. Let

Higgs-Boson Decay to Four Fermions Including a Single Top Quark Below ttˉt \bar t Threshold

The rare decay modes Higgs $\rightarrow$ four light fermions, and Higgs $\rightarrow$ single top-quark + three light fermions for $m_t<M_H<2m_t$, are presented, and phenomenologically interpreted. The angular correlation between fermion planes is presented as a test of the spin and intrinsic parity of the Higgs particle. In Higgs decay to single top, two tree-level graphs contribute in the standard model (SM); one couples the Higgs to $W^+W^-(\sim gM_W)$, and one to t\bar t(\sim g_{top\;yukawa}=m_t/246\GeV). The large Yukawa coupling for m_t>100\GeV makes the second amplitude competitive or dominant for most $M_H,m_t$ values. Thus the Higgs decay rate to single top directly probes the SM universal mechanism generating both gauge boson and fermion masses, and offers a means to infer the Higgs-$t \bar t$ Yukawa coupling when $H\rightarrow t \bar t$ is kinematically disallowed. We find that the modes $pp\rightarrow Xt\bar t(H\rightarrow t\bar b W^{(*)})$ at the SSC, and $e^+ e^-\rightarrow Z\,or\,\nu\bar{\nu} + (H\rightarrow t\bar b W^{(*)})$ at future high energy, high luminosity colliders, may be measureable if $2m_t$ is not too far above $M_H$. We classify non-standard Higgses as gaugeo-phobic, fermio-phobic or fermio-philic, and discuss the Higgs$\rightarrow$ single top rates for these classes.Comment: 30 pages, 6 figures (figures available upon request); VAND-TH-93/

Clustering in Highest Energy Cosmic Rays: Physics or Statistics?

Directional clustering can be expected in cosmic ray observations due to purely statistical fluctuations for sources distributed randomly in the sky. We develop an analytic approach to estimate the probability of random cluster configurations, and use these results to study the strong potential of the HiRes, Auger, Telescope Array and EUSO/OWL/AirWatch facilities for deciding whether any observed clustering is most likely due to non-random sources.Comment: 19 pages, LaTeX, 3 figure

Dust observations of Comet 9P/Tempel 1 at the time of the Deep Impact

On 4 July 2005 at 05:52 UT, the impactor of NASA's Deep Impact (DI) mission crashed into comet 9P/Tempel 1 with a velocity of about 10 km/s. The material ejected by the impact expanded into the normal coma, produced by ordinary cometary activity. The characteristics of the non-impact coma and cloud produced by the impact were studied by observations in the visible wavelengths and in the near-IR. The scattering characteristics of the "normal" coma of solid particles were studied by comparing images in various spectral regions, from the UV to the near-IR. For the non-impact coma, a proxy of the dust production has been measured in various spectral regions. The presence of sublimating grains has been detected. Their lifetime was found to be about 11 hours. Regarding the cloud produced by the impact, the total geometric cross section multiplied by the albedo was measured as a function of the color and time. The projected velocity appeared to obey a Gaussian distribution with the average velocity of the order of 115 m/s. By comparing the observations taken about 3 hours after the impact, we have found a strong decrease in the cross section in J filter, while that in Ks remained almost constant. This is interpreted as the result of sublimation of grains dominated by particles of sizes of the order of some microns.Comment: Accepted by A&

Cyclotron resonance of the quasi-two-dimensional electron gas at Hg1-xCdxTe grain boundaries

The magnetotransmission of a p-type Hg0.766Cd0.234Te bicrystal containing a single grain boundary with an inversion layer has been investigated in the submillimetre wavelength range. For the first time the cyclotron resonance lines belonging to the various electric subbands of a quasi-two-dimensional carrier system at a grain boundary could be detected. The measured cyclotron masses and the subband densities determined from Shubnikov-de Haas experiments are compared with theoretical predictions and it is found that the data can be explained very well within the framework of a triangular well approximation model which allows for non-parabolic effects