Bruno Leibundgut

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We present constraints on the dark energy equation-of-state parameter, w = P/(ρc 2), using 60 Type Ia supernovae (SNe Ia) from the ESSENCE su-pernova survey. We derive a set of constraints on the nature of the dark energy assuming a flat Universe. By including constraints on (Ω M , w) from baryon acoustic oscillations, we obtain a value for a static(More)
The first cosmological results from the ESSENCE supernova survey (Wood-Vasey et al. 2007) are extended to a wider range of cosmological models including dynamical dark energy and non-standard cosmological models. We fold in a greater number of external data sets such as the recent Higher-z release of high-redshift supernovae (Riess et al. 2007) as well as(More)
Type Ia Supernovae hold great promise to measure the cosmic deceleration. The diversity observed among these explosions, however , complicates their ability to measure cosmological parameters considerably. The comparison of near and distant objects depends critically on the global properties of the samples. Systematic errors are introduced in cases where(More)
We report results of a systematic radial velocity survey for double degenerate (DD) binaries as potential progenitors of type Ia supernovae: SPY (ESO Supernovae Ia Progenitor surveY). More than 1000 white dwarfs (WDs) and pre-white dwarfs were observed with the VLT. The aim of SPY is to perform a statistically significant test of the DD scenario. We give an(More)
Between 1983 and 1985, 257 infertile men were examined for any present varicocele by means of the Doppler sonography, telethermography and palpation. Based on these findings, the spermiogram and the infertility history, high ligation of the spermatic vein was indicated in 89 patients with varicocele and a median duration of infertility of 36 months (6-88(More)
The High-z Supernova Search Team has discovered and observed 8 new supernovae in the redshift interval z = 0.3–1.2. These independent observations, analyzed by similar but distinct methods, confirm the result of Riess et al. (1998a) and Perlmutter et al. (1999) that supernova luminosity distances imply an accelerating universe. More importantly, they extend(More)
Immunological deposits in the testis and circulating antibodies to spermatozoa are presented as a possible explanation for infertility in man. Testicular biopsy specimens from infertile patients (N = 52) as well as from fertile controls (N = 6) were analyzed immunohistochemically by using semithin sections. Immunoglobulin deposits were found in the testes(More)
We have started a large survey for radial velocity variations in white dwarfs (PI R. Napiwotzki) with the aim of finding close double degenerates, which could be precursor systems for SNe Ia. The UVES spectrograph at the ESO VLT is used to obtain high resolution spectra with good S/N. During this project 1500 white dwarfs will be observed. This unique data(More)
We present photometric and spectroscopic observations of 23 high redshift supernovae spanning a range of z = 0.34 − 1.03, 9 of which are unambiguously classified as Type Ia. These supernovae were discovered during the IfA Deep Survey, which began in September 2001 and observed a total of 2.5 square degrees to a depth of approximately m ≈ 25 − 26 in RIZ over(More)