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We report our efforts to constrain the form of the low-mass star and brown dwarf mass function via Bayesian inference. Recent surveys of M, L, and T dwarfs in the local solar neighborhood are an essential component of our study.…

Astrophysics · Physics 2009-11-10 P. R. Allen , D. W. Koerner , I. N. Reid , D. E. Trilling

The evolution of differential ages of passive galaxies at different redshifts (cosmic chronometers) has been proved to be a method potentially able to constrain the Hubble parameter in a cosmology-independent way, but the systematic…

Astrophysics of Galaxies · Physics 2022-01-24 Michele Moresco , Raul Jimenez , Licia Verde , Andrea Cimatti , Lucia Pozzetti

Gaussian process regression is a frequently used statistical method for flexible yet fully probabilistic non-linear regression modeling. A common obstacle is its computational complexity which scales poorly with the number of observations.…

Methodology · Statistics 2026-03-10 Adam Gorm Hoffmann , Claus Thorn Ekstrøm , Andreas Kryger Jensen

Gaussian processes are a fundamental statistical tool used in a wide range of applications. In the spatio-temporal setting, several families of covariance functions exist to accommodate a wide variety of dependence structures arising in…

Methodology · Statistics 2017-11-22 Henry R. Scharf , Mevin B. Hooten , Devin S. Johnson , John W. Durban

Multivariate point processes are widely applied to model event-type data such as natural disasters, online message exchanges, financial transactions or neuronal spike trains. One very popular point process model in which the probability of…

Statistics Theory · Mathematics 2023-01-27 Deborah Sulem , Vincent Rivoirard , Judith Rousseau

One of the most promising tracers of the Galactic potential in the halo region are stellar streams. However, individual stream fits can be limited by systematic biases. To study these individual stream systematics, we fit streams in Milky…

Astrophysics of Galaxies · Physics 2021-11-17 Stella Reino , Robyn E. Sanderson , Nondh Panithanpaisal , Elena M. Rossi , Konrad Kuijken

Existing stellar X-ray surveys suggest major problems in our understanding of the evolution of stellar magnetic activity in solar and late-type stars, reaching conflicting conclusions over the rate of decay of X-ray activity and the…

Solar and Stellar Astrophysics · Physics 2019-08-19 Nicholas J. Wright , Jeremy J. Drake , Francesca Civano

Quantitative understanding of human behaviors provides elementary comprehension of the complexity of many human-initiated systems. A basic assumption embedded in the previous analyses on human dynamics is that its temporal statistics are…

Physics and Society · Physics 2009-07-31 Tao Zhou , Xiaopu Han , Binghong Wang

The variability of H$\alpha$ chromospheric activity of solar-like stars is investigated by using the time-domain data of LAMOST Medium-Resolution Spectroscopic Survey (MRS). We use $R_\mathrm{H\alpha}$ index (ratio of H$\alpha$ luminosity…

Solar and Stellar Astrophysics · Physics 2025-12-10 Han He , Ali Luo , Haotong Zhang , Song Wang

Context. Solar activity cycles vary in amplitude and duration. The variations can be at least partly explained by fluctuations in dynamo parameters. Aims. We want to restrict uncertainty in fluctuating dynamo parameters and find out which…

Solar and Stellar Astrophysics · Physics 2018-07-18 L. L. Kitchatinov , A. V. Mordvinov , A. A. Nepomnyashchikh

It is known that the tilt angles of active regions increase with their latitude (Joy's law). It has never been checked before, however, whether the average tilt angles change from one cycle to another. Flux transport models show the…

Solar and Stellar Astrophysics · Physics 2015-05-18 Maria Dasi-Espuig , Sami K. Solanki , Natasha A. Krivova , Robert H. Cameron , Tania Peñuela

The length of the solar activity cycle fluctuates considerably. The temporal evolution of the corresponding cycle phase, that is, the deviation of the epochs of activity minima or maxima from strict periodicity, provides relevant…

Solar and Stellar Astrophysics · Physics 2023-03-15 E. Weisshaar , R. H. Cameron , M. Schüssler

We describe a model of dark matter halo abundances and clustering which combines the two most widely used approaches to this problem: that based on peaks and the other based on excursion sets. Our approach can be thought of as addressing…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 Aseem Paranjape , Ravi K. Sheth

Dynamical processes on time-varying complex networks are key to understanding and modeling a broad variety of processes in socio-technical systems. Here we focus on empirical temporal networks of human proximity and we aim at understanding…

Physics and Society · Physics 2013-11-01 Laetitia Gauvin , André Panisson , Ciro Cattuto , Alain Barrat

The application of the Wavelet analysis and Fourier analysis to the dataset of variations of radiation fluxes of solar-like stars and the Sun is examined. In case of the Sun the wavelet-analysis helped us to see a set of values of periods…

Solar and Stellar Astrophysics · Physics 2012-04-06 E. A. Bruevich , I. K. Rozgacheva

Two motions in the galactic plane have been detected and characterized, based on the determination of a common systematic component in Hipparcos catalogue proper motions. The procedure is based only on positions, proper motions and…

Astrophysics · Physics 2007-05-23 Carlos Abad , Katherine Vieira

We consider multi-task regression models where the observations are assumed to be a linear combination of several latent node functions and weight functions, which are both drawn from Gaussian process priors. Driven by the problem of…

Machine Learning · Statistics 2018-12-05 Astrid Dahl , Edwin V. Bonilla

This article introduces estimators of trend and seasonality for time series of point processes. We assume the point processes follow a temporal or spatial doubly-stochastic Poisson model with log-Gaussian intensity functions. The proposed…

Methodology · Statistics 2026-05-22 Daniel Gervini , Simon A. Kopischke

Several solar-like stars exhibit cyclic magnetic activity similar to the Sun as found in photospheric and chromospheric emission. We want to understand the physical mechanism involved in rotational dependence of these activity cycle…

Solar and Stellar Astrophysics · Physics 2018-08-22 Jörn Warnecke

We estimate the halo mass function (HMF) by applying the excursion set approach to the non-linear cosmic density field. Thereby, we account for the non-Gaussianity of today's density distribution and constrain the HMF independent of the…

Cosmology and Nongalactic Astrophysics · Physics 2020-02-25 Laila Linke , Johannes Schwinn , Matthias Bartelmann