Spherical Harmonic Analysis of the Angular Distribution of Gamma-Ray Bursts

We compute the angular power spectrum C_l of the BATSE 3B catalog, and find no evidence for clustering on any scale. These constraints bridge the entire range from small scales, probing source clustering and repetition, to large scales constraining possible Galactic anisotropies, or those from nearby cosmological large scale structures.Comment: 5 page conf. proceedings, with one figure included. Postscript. More detailed version at http://astro.berkeley.edu/~max/bursts.html (faster from the US), from http://www.mpa-garching.mpg.de/~max/bursts.html (faster from Europe) or from [email protected]

Improved limits on gamma ray burst repetition

We tighten previous upper limits on gamma ray burst repetition by analyzing the angular power spectrum of the BATSE 3B catalog of 1122 bursts. At 95% confidence, we find that no more than 2% of all observed bursts can be labeled as repeaters, even if no sources are observed to repeat more than once. If a fraction f of all observed bursts can be labeled as repeaters that are observed to burst v times each, then all models with (v-1)f>0.05 are ruled out at 99% confidence, as compared to the best previous 99% limit (v-1)f>0.27. At 95% confidence, our new limit is (v-1)f>0.02. Thus even a cluster of 6 events from a single source would have caused excess power above that present in the 3B catalog. We conclude that the current BATSE data are consistent with no repetition of classical gamma ray bursts, and that any repeater model is severely constrained by the near perfect isotropy of their angular distribution.Comment: 18 pages, with 2 figures included. Postscript. Submitted to ApJL. Latest version at http://astro.berkeley.edu/~max/repeaters.html (faster from the US), from http://www.mpa-garching.mpg.de/~max/repeaters.html (faster from Europe) or from [email protected]

The Angular Power Spectrum of BATSE 3B Gamma-Ray Burst

We compute the angular power spectrum C_l from the BATSE 3B catalog of 1122 gamma-ray bursts, and find no evidence for clustering on any scale. These constraints bridge the entire range from small scales (which probe source clustering and burst repetition) to the largest scales (which constrain possible anisotropies from the Galactic halo or from nearby cosmological large scale structures). We develop an analysis technique that takes the angular position errors into account, which enables us to place tight upper limits on the clustering down to scales l\approx 60, corresponding to a few degrees on the sky. The minimum-variance burst weighting that we employ is graphically visualized as an all-sky map where each burst is smeared out by an amount corresponding to its position uncertainty. We also present separate band-pass filtered sky maps for the quadrupole term and for the multipole-ranges l=3-10 and l=11-30, so that the fluctuations on different angular scales can be separately inspected for visual features such as localized ``hot spots" or structures aligned with the Galactic plane. These filtered maps reveal no apparent deviations from isotropy.Comment: 31 pages, with 10 figures included. Postscript. Submitted to ApJ. Latest version (and color figures) at http://astro.berkeley.edu/~max/bursts.html (faster from the US), from http://www.mpa-garching.mpg.de/~max/bursts.html (faster from Europe) or from [email protected]

The Angular Power Spectrum of BATSE 3B Gamma-Ray Bursts

We compute the angular power spectrum C(sub l) from the BATSE 3B catalog of 1122 gamma-ray bursts and find no evidence for clustering on any scale. These constraints bridge the entire range from small scales (which probe source clustering and burst repetition) to the largest scales (which constrain possible anisotropics from the Galactic halo or from nearby cosmological large-scale structures). We develop an analysis technique that takes the angular position errors into account. For specific clustering or repetition models, strong upper limits can be obtained down to scales l approx. equal to 30, corresponding to a couple of degrees on the sky. The minimum-variance burst weighting that we employ is visualized graphically as an all-sky map in which each burst is smeared out by an amount corresponding to its position uncertainty. We also present separate bandpass-filtered sky maps for the quadrupole term and for the multipole ranges l = 3-10 and l = 11-30, so that the fluctuations on different angular scales can be inspected separately for visual features such as localized 'hot spots' or structures aligned with the Galactic plane. These filtered maps reveal no apparent deviations from isotropy

The Angular Power Spectrum of BATSE 3B Gamma-Ray Bursts

We compute the angular power spectrum C1 from the BATSE 3B catalog of 1122 gamma-ray burts and find no evidence of clustering on any scale. These constraints bridge the entire range from samall scales (which probe source clustering and burst repetition) to the largest scales (which constrain possible anisotropies from the Galactic hal or from nearby cosmological large-scale structures). We develop an analysis tecnique that takes the angular position errors into account. For specific clustering or repetition models, strong upper limits can be obtained down to scales l ~ 30, corresponding to abou couple of degrees on the sky. The minimum-variance burst weighting that we employ to visulaized graphically as an all-sky map in which each burts is smeared out by an amount correponding to its position uncertainity. We also present separate bandpas-filtered sky maps for the quadrupole term and for the multipole ranges l = 3-10 and l - 11-30, so that the fluctuations on different angular scales can be inspected separately for visual features such as localized hot spots or structures aligned wit the Galactic plane. These filtered maps reveal no apparent deviations from isotropy

Improved Limits on Gammy-Ray Burst Repetition from BATSE

We tighten previous upper limits on gamma-ray burst repetition by analyzing the angular power spectrum of the BATSE 3B catalog of 1122 bursts. At 95% confidence, we find that no more that 2% of all observed bursts can be labeled as repeaters, even if no sources are observed to repeat more than once. If a fraction f of all observed bursts can be labeled as repeaters that are observed to bursts v times each, then all models ( v - 1) f \u3e~ 0.05 are rules out as 99% confidence, as compares to the best previous 99% limit (v - 1) f \u3e~ 0.27. At 95% conficenc, our new limit is (v - 1) f \u3e~ 0.02. Thus, even a cluster of six events from a single source would have caused excess power above that present in the 3B catalog. We conclude that the current BATSE data are consistent with no repetition of classical gamma-ray burts and that any repeater model is severely constrained by the near-perfect isotropy of their angular distribution

Breed and Swine Lymphocyte Antigen Haplotype Differences in Agglutination Titers Following Vaccination with B. Bronchiseptica

Genetic differences in immune response to B. bronchiseptica after vaccination with a commercial B. bronchiseptica bacterin were investigated in 1,069 8-wk-old pigs. These pigs were from 65 litters born in the spring and 66 litters born in the fall of 1982 and were purebreds from the Chester White (n = 128), Duroc (n = 281), Hampshire (n = 143), Landrace (n = 309) and Yorkshire (n = 208) breeds. Each litter was raised separately. Individual pigs were vaccinated im at 4 and 6 wk of age with 2 ml of B. bronchiseptica bacterin. At 8 wk of age, 8 ml of blood were collected from each animal and serum prepared to determine agglutinating antibody titers against B. bronchiseptica bacterin by a bacterial agglutination method. In addition, lymphocytes were separated from 1 ml of heparinized blood and used to determine Swine Lymphocyte Antigen (SLA) haplotypes by using cytotoxic antibodies against the SLA complex. Antisera for 3 SLA haplotypes were made available by the National Institutes of Health. Results indicated that breed of pig (P\u3c.01) and dam of pig (P\u3c.01) affected the immune response of the pig after B. bronchiseptica vaccination. Higher immune response was also associated (P\u3c.05) with one of the SLA haplotypes tested. Heritability estimates for immune response following vaccination were .10 ± .12 (half-sib) and .42 ± .19 (full-sib). Results suggest that the relationship of the SLA complex to immune response in the pig and nonadditive genetic and maternal effects on immune response should be further investigated

Improved Limits on Gamma-Ray Burst Repetition from BATSE

We tighten previous upper limits on gamma-ray burst repetition by analyzing the angular power spectrum of the BATSE 3B catalog of 1122 bursts. At 95% confidence, we find that no more than 2% of all observed bursts can be labeled as repeaters, even if no sources are observed to repeat more than once. If a fraction f of all observed bursts can be labeled as repeaters that are observed to burst upsilon times each, then all models with (upsilon - 1)f greater than or equal to 0.05 are ruled out at 99% confidence, as compared to the best previous 99% limit (upsilon - 1)f greater than or equal to 0.27. At 95% confidence, our new limit is (upsilon - 1)f greater than or equal to 0.02. Thus, even a cluster of six events from a single source would have caused excess power above that present in the 3B catalog. We conclude that the current BATSE data are consistent with no repetition of classical gamma-ray bursts and that any repeater model is severely constrained by the near-perfect isotropy of their angular distribution

An Imaging and Spectroscopic Study of the z=3.38639 Damped Lyman Alpha System in Q0201+1120: Clues to Star Formation Rate at High Redshift

We present the results of a series of imaging and spectroscopic observations aimed at identifying and studying the galaxy responsible for the z = 3.38639 damped lya system in the z = 3.61 QSO Q0201+1120. We find that the DLA is part of a concentration of matter which includes at least four galaxies (probably many more) over linear comoving dimensions, greater than 5h^-1Mpc. The absorber may be a 0.7 L* galaxy at an impact parameter of 15 h^-1 kpc, but follow-up spectroscopy is still required for positive identification. The gas is turbulent, with many absorption components distributed over approximately 270 km/s and a large spin temperature, T_s greater than 4000K. The metallicity is relatively high for this redshift, Z(DLA) approximately 1/20 Z(solar). From consideration of the relative ratios of elements which have different nucleosynthetic timescales, it would appear that the last major episode of star formation in this DLA occurred at z greater than 4.3, more than approximately 500 Myr prior to the time when we observe it.Comment: Accepted for publication in Ap