Large scale electric fields have never been observed in astrophysics AFAIK. The issue of magnetic fields was dealt with in a 2001 paper on systematic effects and the statements made were uncontroversial then. The magnetic field strength in the strong absorbers has been inferred from Faraday...
How do you explain the fact that the host galaxies of the quasar absorbers can be identified in many cases?
e.g. http://adsabs.harvard.edu/abs/2008A%26A...487..583B
Also, this does also does nothing to explain the Lyman-alpha forest -- the dense series of Lyman alpha transitions along the...
Large scale electric fields cannot build up in the plasma; the electric field gradient would rapidly cause mixing of charges.
Magnetic fields in galaxy clusters typically have strength of ~ microGauss, which is roughly 9 orders of magnitude below the strength required to cause significant...
The program has been thoroughly tested with rounds of simulations on synthetic spectra over many years. In all cases, the input value of da/a is recovered with the expected statistical errors.
da/a of 10^(-5) corresponds to shifts of between ~100 and ~230 m/s for the Fe II lines of interest...
q depends on the value of the fine structure constant in the atom. From the formula above, you can see that it is given by d omega / d x, where x = [(alpha_z - alpha_0)/alpha_0]^2.
To the best of my knowledge, the q values can only be calculated, not measured. In principle, if you could go to...
The absorbers are at cosmological redshifts from the quasar. The exact distribution of absorbers isn't uniform, due to galaxy evolution, GR angular size effects (which relates to the chance of getting line of sight intersections), but to a very very rough first approximation absorbers are...
We perform high resolution (R ~ 50,000) spectroscopy on quasar absorbers. The precise origin of the absorption is unknown, but thought to be gas clouds of size ~10 to ~100 pc that are found in both the disk of the galaxy and the halo. The transitions we analyse arise from: Mg I, Mg II, Fe II...
Whilst this might be true if the absorbers were in the galactic cores, many of the absorbers have optical depths much less than unity and appear to be located in the galaxy halo.
You might like to note that estimates of the quasar absorbers sizes range from ~ 10 to ~100 parsecs...
In regions where the continuum fit does not appear good, we allow for a variable continuum. The error from this propagates into the error on each da/a measurement. You can show that in the case where the continuum fit is good, and you do this, that the impact on da/a is negligible (typically any...
Hello all :)
This is Julian from the PRL paper. I'm not willing to debate many of the points here, because the paper is under peer review. Having said that, I'm glad to see that our work has brought much excitement to you over the last few weeks :). The discussion in this thread has been...
I should also point out that Wikipedia gives the moments of inertia for an ellpsoid, of which the oblate spheroid is a restricted case
http://en.wikipedia.org/wiki/Ellipsoid
Gauss law is only really tractable analytically for charged cases about three cases (spherical symmetry, infinite line of charge, infinite plane of charge). Nevertheless, it's always true. if there's no charge inside your region, the surface integral over your gaussian surface is zero.
Mean free path in space should be enormous, not nanometres.
Check out wikipedia: mean free path for maxwellian particles (low T) is given by (sqrt(2) n sigma)^(-1), where n is the number density, and sigma is the effective cross section. The cross section is just given by ~ pi r^2 (classical...