Galaxy Rotation

Disk galaxy rotation curves and dark matter distribution

After explaining the motivation for this article, we briefly recapitulate the methods used to determine somewhat coarsely the rotation curves of our Milky Way Galaxy and other spiral galaxies, especially in their outer parts, and the results of applying these methods. Recent observations and models of the very inner central parts of galaxian rotation curves are only briefly described. We then present the essential Newtonian theory of (disk) galaxy rotation curves. The next two sections present two numerical simulation schemes and brief results. Application of modified Newtonian dynamics to the outer parts of disk galaxies is then described. Finally, attempts to apply Einsteinian general relativity to the dynamics are summarized. The article ends with a summary and prospects for further work in this area

Galaxy Zoo

Galaxy Zoo: The large-scale spin statistics of spiral galaxies in the Sloan Digital Sky Survey

We re-examine the evidence for a violation of large-scale statistical isotropy in the distribution of projected spin vectors of spiral galaxies. We have a sample of $\sim 37,000$ spiral galaxies from the Sloan Digital Sky Survey, with their line of sight spin direction confidently classified by members of the public through the online project Galaxy Zoo. After establishing and correcting for a certain level of bias in our handedness results we find the winding sense of the galaxies to be consistent with statistical isotropy. In particular we find no significant dipole signal, and thus no evidence for overall preferred handedness of the Universe. We compare this result to those of other authors and conclude that these may also be affected and explained by a bias effect.

Nature's Brightest Explostion

Observations of the Naked-Eye GRB 080319B: Implications of Nature's Brightest Explosion

The first gamma-ray burst (GRB) confirmed to be bright enough to be seen with the naked eye, GRB 080319B, allowed for exquisite follow-up across the electromagnetic spectrum. We present our detailed optical and infrared observations of the afterglow, consisting of over 5000 images starting 122 s after the GRB trigger, in concert with our own analysis of the Swift UVOT, BAT, and XRT data. The event is extreme not only in observed properties but intrinsically: it was the most luminous ever recorded at optical wavelengths and had an exceedingly high isotropic-equivalent energy release in gamma-rays

The French

There's a charming article about the French in the New York Times A Guide to the French. Handle With Care

“Every man has two countries, his own and France,” says a character in a play by the 19th- century poet and playwright Henri de Bornier.

“The most beautiful makeup for a woman is passion,” Yves Saint Laurent once said. “But cosmetics are easier to buy.”