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The hierarchical mergers that form the haloes of dark matter surrounding galaxies, groups and clusters are not entirely efficient, leaving substantial amounts of dense substructure, in the form of stripped halo cores or `subhaloes',…

Astrophysics · Physics 2009-11-07 James E. Taylor , Arif Babul

The observed correlation between global low cloud amount and the flux of high energy cosmic rays supports the idea that ionization plays a crucial role in tropospheric cloud formation. We explore this idea quantitatively with a simple model…

Atmospheric and Oceanic Physics · Physics 2009-11-07 David Marsden , Richard E. Lingenfelter

To complement the optical absorption-line survey of diffuse molecular gas in Paper I, we obtained and analyzed far ultraviolet H$_2$ and CO data on lines of sight toward stars in Cep OB2 and Cep OB3. Possible correlations between column…

Astrophysics · Physics 2009-11-13 K. Pan , S. R. Federman , Y. Sheffer , B. -G. Andersson

The influence of solar variability on climate is currently uncertain. Recent observations have indicated a possible mechanism via the influence of solar modulated cosmic rays on global cloud cover. Surprisingly the influence of solar…

Atmospheric and Oceanic Physics · Physics 2011-09-06 Nigel D Marsh , Henrik Svensmark

In cold dark matter cosmological models, structures form and grow by merging of smaller units. Numerical simulations have shown that such merging is incomplete; the inner cores of halos survive and orbit as "subhalos" within their hosts.…

Astrophysics · Physics 2010-04-06 J. Diemand , M. Kuhlen , P. Madau , M. Zemp , B. Moore , D. Potter , J. Stadel

We investigate ionization and heating of gas in the dense, shielded clumps/cores of molecular clouds bathed by an influx of energetic, charged cosmic rays (CRs). These molecular clouds have complex structures, with substantial variation in…

Astrophysics of Galaxies · Physics 2021-06-02 Ellis R. Owen , Alvina Y. L. On , Shih-Ping Lai , Kinwah Wu

Clouds are often considered a highly uncertain barrier for detecting biosignatures on exoplanets, especially given intuition gained from transit surveys. However, for direct imaging reflected light observations, clouds could increase the…

Earth and Planetary Astrophysics · Physics 2025-05-13 Huanzhou Yang , Michelle Hu , Dorian S. Abbot

When a $\gamma$-ray interacts in a semiconductor detector, the resulting electron-hole charge clouds drift towards their respective electrodes for signal collection. These charge clouds will expand over time due to both thermal diffusion…

Instrumentation and Methods for Astrophysics · Physics 2023-04-20 Steven E. Boggs

Various aspects of the connection between cloud cover (CC) and cosmic rays (CR) are analysed. Many features of this connection indicate that there is no direct causal connection between low cloud cover (LCC) and CR in spite of the evident…

Earth and Planetary Astrophysics · Physics 2015-05-13 A. D. Erlykin , G. Gyalai , K. Kudela , T. Sloan , A. W. Wolfendale

We used CO (2-1) and CO (1-0) data cubes to identify molecular clouds and study their kinematics and dynamics in three nearby galaxies and the inner Milky Way. When observed at similar spatial and velocity resolutions, molecular clouds in…

Astrophysics of Galaxies · Physics 2025-11-03 J. W. Zhou , Sami Dib

High-resolution X-ray observations have revealed cavities and `cold fronts' with sharp edges in temperature, density, and metallicity within galaxy clusters. Their presence poses a puzzle since these features are not expected to be…

Astrophysics · Physics 2009-11-13 L. J. Dursi , C. Pfrommer

We study the impact of merger events on the strong lensing properties of galaxy clusters. Previous lensing simulations were not able to resolve dynamical time scales of cluster lenses, which arise on time scales which are of order a Gyr. In…

The fraction of substructures required to account for anomalous flux ratios in gravitational lens systems appears to be higher than that predicted in the standard cold dark matter cosmology. We present a possible alternative route to…

Astrophysics · Physics 2009-11-10 Masamune Oguri

We expand our study on the dispersion of polarization angles in molecular clouds. We show how the effect of signal integration through the thickness of the cloud as well as across the area subtended by the telescope beam inherent to dust…

Astrophysics of Galaxies · Physics 2014-11-20 Martin Houde , John E. Vaillancourt , Roger H. Hildebrand , Shadi Chitsazzadeh , Larry Kirby

A planet's spectrum is dynamic and only represents a time-dependent snapshot of its properties. Changing atmospheric conditions due to climate and weather patterns, particularly variation in cloud cover, can significantly affect the…

Earth and Planetary Astrophysics · Physics 2025-03-13 Soumil Kelkar , Prabal Saxena , Ravi Kopparapu , Joy Monteiro

We investigate the uncertainties affecting the temperature profiles of dense cores of interstellar clouds. In regions shielded from external ultraviolet radiation, the problem is reduced to the balance between cosmic ray heating, line…

Astrophysics of Galaxies · Physics 2015-05-30 M. Juvela , N. Ysard

Diffuse, extended radio emission in galaxy clusters, commonly referred to as radio halos, indicate the presence of high energy cosmic ray (CR) electrons and cluster-wide magnetic fields. We can predict from theory the expected surface…

High Energy Astrophysical Phenomena · Physics 2017-11-29 Joshua Wiener , Ellen G. Zweibel , S. Peng Oh

We use ray-tracing through the Millennium simulation to study how secondary matter structures along the line-of-sight and the stellar mass in galaxies affect strong cluster lensing, in particular the cross-section for giant arcs.…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 Ewald Puchwein , Stefan Hilbert

Throughout the passage within the Galactic halo, high-velocity clouds (HVCs) sweep up ambient magnetic fields and form stretched and draped configurations of magnetic fields around them. Many earlier numerical studies adopt spherically…

Astrophysics of Galaxies · Physics 2023-05-03 Seoyoung Lyla Jung , Asger Grønnow , Naomi McClure-Griffiths

Cold atomic clouds are promising platforms for generating correlated photons, but multiple scattering and associated Doppler broadening limit their temporal coherence. Here we demonstrate that cloud geometry provides a powerful means to…