Evaluating the quality of selective emitter structures by imaging the emitter saturation current density

A method to derive the emitter saturation current density J0e with lateral resolution is applied to investigate selective emitter structures. The method uses PL lifetime imaging at several injection densities to laterally evaluate J0e by applying the method of Kane and Swanson [1] pixel by pixel. Samples with two-sided diffused emitters on lowlydoped Cz wafers were used to produce selective emitter structures by laser doping of the phosphorus-rich glass (LDSE). By comparison of experimental and numerical simulation results of J0e linescans, a limited resolution of a feature size of an inhomogeneous emitter is determined to be theoretically between 0.5-1.0 mm and experimentally about 2 mm. The method was successfully applied to investigate the dependence of J0e on the laser power of a selective emitter structure. The expected behaviour of a maximum J0e for medium laser intensities is observed. The method is suitable to evaluate the selective emitter process and its optimization.BMU/032520

Chandra and ASCA X-ray Observations of the Radio Supernova SN1979C IN NGC 4321

We report on the X-ray observation of the radio selected supernova SN1979C carried out with ASCA in 1997 December and serendipitously available from a Chandra Guaranteed Time Observation in 1999 November. The supernova, of type SN II-Linear (SN IIL), was first observed in the optical and occurred in the weakly barred, almost face on spiral galaxy NGC 4321 (M100). The galaxy, a member of the Virgo S cluster, is at a distance of 17.1 Mpc, and contains at least three other supernovae discovered in this century. The useful exposure time was ~25 ks for the Solid-State Imaging Spectrometer (SIS), ~28 ks for the Gas Scintillation Imaging Spectrometer (GIS), and ~2.5 ks for Chandra's Advanced CCD Imaging Spectrometer (ACIS). No point source was detected at the radio position of SN1979C in a 3' diameter half power response circle in the ASCA data. The background and galaxy subtracted SN signal had a 3sigma upper limit to the flux of 6.3x10^-14 ergs/s/cm^-2 in the full ASCA SIS band (0.4-10.0 keV) and a 3sigma upper limit of <3-4x10^-14 erg/s/cm^2 in the 2-10 keV band. In the Chandra data, a source at the position of SN1979C is marginally detected at energies below 2 keV at a flux consistent with the ROSAT HRI detection in 1995. At energies above 2 keV, no source is detected with an upper limit of ~3x10^-14 erg/s/cm^-2. These measurements give the first ever x-ray flux limit of a Type IIL SN above 2 keV which is an important diagnostic of the outgoing shock wave ploughing through the circumstellar medium.Comment: 8 pages, 2 figures, accepted A

Extrapolation of Galactic Dust Emission at 100 Microns to CMBR Frequencies Using FIRAS

We present predicted full-sky maps of submillimeter and microwave emission from the diffuse interstellar dust in the Galaxy. These maps are extrapolated from the 100 micron emission and 100/240 micron flux ratio maps that Schlegel, Finkbeiner, & Davis (1998; SFD98) generated from IRAS and COBE/DIRBE data. Results are presented for a number of physically plausible emissivity models. We find that no power law emissivity function fits the FIRAS data from 200 - 2100 GHz. In this paper we provide a formalism for a multi-component model for the dust emission. A two-component model with a mixture of silicate and carbon-dominated grains (motivated by Pollack et al., 1994}) provides a fit to an accuracy of about 15% to all the FIRAS data over the entire high-latitude sky. Small systematic differences are found between the atomic and molecular phases of the ISM. Our predictions for the thermal (vibrational) emission from Galactic dust at \nu < 3000 GHz are available for general use. These full-sky predictions can be made at the DIRBE resolution of 40' or at the higher resolution of 6.1 arcmin from the SFD98 DIRBE-corrected IRAS maps.Comment: 48 pages, AAS LaTeX, 6 figures, ApJ (accepted). Data described in the text, as well as 4 additional figures, are available at http://astro.berkeley.edu/dus

Blue horizontal branch stars in the Sloan Digital Sky Survey: II. Kinematics of the Galactic halo

We carry out a maximum-likelihood kinematic analysis of a sample of 1170 blue horizontal branch (BHB) stars from the Sloan Digital Sky Survey presented in Sirko et al. (2003) (Paper I). Monte Carlo simulations and resampling show that the results are robust to distance and velocity errors at least as large as the estimated errors from Paper I. The best-fit velocities of the Sun (circular) and halo (rotational) are 245.9 +/- 13.5 km/s and 23.8 +/- 20.1 km/s but are strongly covariant, so that v_0 - v_halo = 222.1 +/- 7.7 km/s. If one adopts standard values for the local standard of rest and solar motion, then the halo scarcely rotates. The velocity ellipsoid inferred for our sample is much more isotropic [(sigma_r,sigma_theta,sigma_phi) = (101.4 +/- 2.8, 97.7 +/- 16.4, 107.4 +/- 16.6) km/s] than that of halo stars in the solar neighborhood, in agreement with a recent study of the distant halo by Sommer-Larsen et al. (1997). The line-of-sight velocity distribution of the entire sample, corrected for the Sun's motion, is accurately gaussian with a dispersion of 101.6 +/- 3.0 km/s.Comment: 23 pages including 4 figures, 1 color; submitted to A

What Produced the Ultraluminous Supernova Remnant in NGC 6946?

The ultraluminous supernova remnant (SNR) in NGC 6946 is the brightest known SNR in X-rays, ~1000 times brighter than Cas A. To probe the nature of this remnant and its progenitor, we have obtained high-dispersion optical echelle spectra. The echelle spectra detect H-alpha, [N II], and [O III] lines, and resolve these lines into a narrow (FWHM ~20--40 km/s) component from un-shocked material and a broad (FWHM ~250 km/s) component from shocked material. Both narrow and broad components have unusually high [N II]/H-alpha ratios, ~1. Using the echelle observation, archival HST images, and archival ROSAT X-ray observations, we conclude that the SNR was produced by a normal supernova, whose progenitor was a massive star, either a WN star or a luminous blue variable. The high luminosity of the remnant is caused by the supernova ejecta expanding into a dense, nitrogen-rich circumstellar nebula created by the progenitor.Comment: 20 pages, 5 figures. To be published in The Astronomical Journal, March 200

Digital Deblurring of CMB Maps II: Asymmetric Point Spread Function

In this second paper in a series dedicated to developing efficient numerical techniques for the deblurring Cosmic Microwave Background (CMB) maps, we consider the case of asymmetric point spread functions (PSF). Although conceptually this problem is not different from the symmetric case, there are important differences from the computational point of view because it is no longer possible to use some of the efficient numerical techniques that work with symmetric PSFs. We present procedures that permit the use of efficient techniques even when this condition is not met. In particular, two methods are considered: a procedure based on a Kronecker approximation technique that can be implemented with the numerical methods used with symmetric PSFs but that has the limitation of requiring only mildly asymmetric PSFs. The second is a variant of the classic Tikhonov technique that works even with very asymmetric PSFs but that requires discarding the edges of the maps. We provide details for efficient implementations of the algorithms. Their performance is tested on simulated CMB maps.Comment: 9 pages, 13 Figure

A Deep ROSAT HRI Observation of NGC 1313

We describe a series of observations of NGC 1313 using the ROSAT HRI with a combined exposure time of 183.5 ksec. The observations span an interval between 1992 and 1998; the purpose of observations since 1994 was to monitor the X-ray flux of SN1978K, one of several luminous sources in the galaxy. No diffuse emission is detected in the galaxy to a level of ~1-2x10^37 ergs/s/arcmin^-2. A total of eight sources are detected in the summed image within the D_25 diameter of the galaxy. The luminosities of five of the eight range from \~6x10^37 to ~6x10^38 erg/s; these sources are most likely accreting X-ray binaries, similar to sources obseved in M31 and M33. The remaining three sources all emit above 10^39 erg/s. We present light curves of the five brightest sources. Variability is detected at the 99.9% level from four of these. We identify one of the sources as an NGC 1313 counterpart of a Galactic X-ray source. The light curve, though crudely sampled, most closely resembles that of a Galactic black hole candidate such as GX339-4, but with considerably higher peak X-ray luminosity. An additional seven sources lie outside of the D_25 diameter and are either foreground stars or background AGN.Comment: 18 pages, 9 figures; accepted AJ, scheduled for November 200