Dear all,
In a recent talk, I have heard that speed of gravitational waves is non-dispersive.
How is it proved "observationally" in LIGO detections that all the frequencies travel with the same speed, so one can say the speed is non-dispersive?
Dear all,
I am reading the paper "Cosmic dynamics in the era of Extremely Large Telescopes " by Liske et al. about redshift.
I get the physical meaning of redshift drift, but when it comes to the error bars, I am confused.
- Aren't the error bars given in equation (15) ?
- Isn't this function...
Hi!
Can anyone tell me what the radial BAO size method is?
how do people use it to get to the H(z)?
I am reading the paper "Constraints on the Dark Side of the Universe and Observational Hubble Parameter Data " by Zhang et al. and I think I am lost!
Can anyone tell me very simple, how they do...
So zero is not smack dab in the middle of the range, but it is -0.01. right?
do they conclude the variation is zero because of -0.01 is a small number near 0?
But how this "null result" given in this number? $\Delta \alpha/ \alpha = (-0.01\pm0.26) \times 10^{-5}$ which is for instance given in CONSTRAINING THE VARIATION OF THE FINE-STRUCTURE CONSTANT WITH OBSERVATIONS OF NARROW QUASAR ABSORPTION LINES" by Songaila et. al ?
I mean, how is 0 at the...
Thanks a lot for the clear reply.
I'd like to ask two other questions:
- About this variation, in recent papers like " High-precision limit on variation in the fine-structure constant from a single quasar absorption system " by Kotus et. al mention that the measured variation for alpha is...
Hi everyone,
I am new to observations and observational terms!
I am reading the paper "constraining the time variation of the fine-structure constant" by Srianand et. al
in the section "constraining alpha with QSO absorption lines" there is a sentence saying "... rest wavelengths of MG II ...
Dear Chiro,
So you mean I can change the shape of the distribution to a nomal one?
but is it a right thing to do?
I mean if there are observational points, then doesn't this change the data completely?!
I think it means that the mean is 2. and as the distribution is normal, the \begin{equation} \mu^2=0.1\end{equation}
However if the distribution is not normal, then \begin{equation} \mu^2\end{equation} would be different from left and right side of the mean.
yes, it means it can go from 1.9 to 2.9.
But until now, I have used Chi squared test only for normal distributions, which are for instance:
\begin{equation}f_i = 2_{0.1}^{0.1}\end{equation}
i.e. error in both sides are the same.
Hi everyone.
I am totally new to statistics so my question may or may not be simple!
I know that for the data fitting we can do a chi squared test like:
\begin{equation} \chi^2 = \Sigma \frac{(f_{data}-f_{model})^2}{(error_{data})^2}\end{equation}
So I have been doing this for a while, but now...
Dear all,
I am looking for observational data for the number count of galaxy mass function:
\begin{equation} dn/dM\end{equation} in terms of redshift and also mass, to compare with theories.
I know that I can use HIPASS data (most probably), but as I am new to the field, I have to idea:
1-...
Hi everyone,
I am looking for the correct form of the growth factor in large scale structure.
I have found two different equations which I think are not consistent! Can anyone please tell me why it is like this?
The first one if from the book "formation of the structure in the universe" Edited...