Nonlinear correlations of daily temperature records over land

International audienceWe present a near global statistics on the correlation properties of daily temperature records. Data from terrestrial meteorological stations in the Global Daily Climatology Network are analyzed by means of detrended fluctuation analysis. Long-range temporal correlations extending up to several years are detected for each station. In order to reveal nonlinearity, we evaluated the magnitude of daily temperature changes (volatility) by the same method. The results clearly indicate the presence of nonlinearities in temperature time series, furthemore the geographic distribution of correlation exponents exhibits well defined clustering

Ancestral Spin Information in Gravitational Waves from Black Hole Mergers

The heaviest black holes discovered through gravitational waves have masses that are difficult to explain with current standard stellar models. This discrepancy may be due to a series of hierarchical mergers, where the observed black holes are themselves the products of previous mergers. Here we present a method to estimate the masses and spins of previous generations of black holes based on the masses and spins of black holes in a binary. Examining the merger GW190521, we find that assuming black hole spins that are consistent with those of merger remnants will alter the reconstructed ancestral spins when compared to results with uninformed priors. At the same time, the inclusion of black hole spins does not significantly affect the mass distributions of the ancestral black holes.Comment: 4 pages, 2 figure

A Population of Short-Period Variable Quasars from PTF as Supermassive Black Hole Binary Candidates

Supermassive black hole binaries (SMBHBs) at sub-parsec separations should be common in galactic nuclei, as a result of frequent galaxy mergers. Hydrodynamical simulations of circumbinary discs predict strong periodic modulation of the mass accretion rate on time-scales comparable to the orbital period of the binary. As a result, SMBHBs may be recognized by the periodic modulation of their brightness. We conducted a statistical search for periodic variability in a sample of 35,383 spectroscopically confirmed quasars in the photometric database of the Palomar Transient Factory (PTF). We analysed Lomb-Scargle periodograms and assessed the significance of our findings by modeling each individual quasar's variability as a damped random walk (DRW). We identified 50 quasars with significant periodicity beyond the DRW model, typically with short periods of a few hundred days. We find 33 of these to remain significant after a re-analysis of their periodograms including additional optical data from the intermediate-PTF and the Catalina Real-Time Transient Survey (CRTS). Assuming that the observed periods correspond to the redshifted orbital periods of SMBHBs, we conclude that our findings are consistent with a population of unequal-mass SMBHBs, with a typical mass ratio as low as q = M2/M1 ~ 0.01.Comment: MNRAS (accepted), new section 4.

IS900 Restriction Fragment Length Polymorphism (RFLP) Analysis of Mycobacterium avium subsp. paratuberculosis Isolates from Goats and Cattle in Norway

In Norway, paratuberculosis has been frequently diagnosed in goats, while cattle have been almost free of the infection. This difference in prevalence between goats and cattle has led to speculations about the existence of a Mycobacterium avium subsp. paratuberculosis (M. a. paratuberculosis) isolate that is non-pathogenic for cattle. There is little information available on genotypic variation of M. a. paratuberculosis isolated from animals in Norway. In the present study, genotypic information on 51 isolates from goats and four isolates from cattle in Norway was obtained by use of IS900 restriction fragment length polymorphism (RFLP) analysis. All isolates from cattle and 84% of the isolates from goats had the same RFLP pattern (B-C1). Five RFLP patterns not previously detected were found. No genotypic variation that could explain a difference in host origin was found between the isolates from cattle and the majority of the Norwegian goat isolates. This lack of difference indicates that the most common M. a. paratuberculosis isolates in Norway may infect both cattle and goats