11 papers · 1 filter
Bending instabilities at the origin of persistent warps
Y. Revaz, D. Pfenniger
Based on N-body simulations, we show that realistic galactic disks are subject to bending instabilities of fire-hose type when the disks are substantially self-gravitating, that is…
Fragmentation in Kinematically Cold Disks
Daniel Huber, Daniel Pfenniger
Gravity is scale free. Thus gravity may form similar structures in self-gravitating systems on different scales. Indeed, observations of the interstellar medium, spiral disks and c…
N-body simulations of warped galaxies
Yves Revaz, Daniel Pfenniger
Two methods generating warped galaxies with N-body simulations are presented. One uses an external potential as a disturber while the other is based on material accretion. The resu…
Maximum Galactic Disks vs. Hot Dark Halos
Daniel Pfenniger
A series of arguments is presented for heavy galaxy disks not only in the optical regions, but also in the dark matter dominated regions of spirals. We are testing this possibility…
Which thermal physics for gravitationally unstable media?
Daniel Pfenniger
We remind that the assumptions almost universally adopted among astronomers concerning the physics to use to describe rarefied cosmic gases remain often without justifications, mai…
Clumpuscule Formation at High Redshift
F. Combes, D. Pfenniger
Over the last two decades, realistic studies have often concluded that the first bound objects to form can be very small, much smaller than a solar mass. After recombination, the J…