Lack of time dilation in type 1a supernova

[wolram]

Here is one for every one to pull apart, it goes beyond every thing I have learnt.

arXiv:1804.10274 [pdf, other]
Lack of time dilation in type Ia supernovae and Gamma-Ray Bursts
David F. Crawford
Comments: 4 pages, 2 figures and 1 table
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

A fundamental property of any expanding universe is that any time dependent characteristics of distant objects must appear to scale by the factor (1+z). This is called time dilation. Light curves of type Ia supernovae and the duration of Gamma-Ray Bursts (GRB) are the only observations that can directly measure time dilation over a wide range of redshifts. An analysis of raw observations of type Ia supernovae light curves shows that their widths are proportional to (1+z)(0.088±0.036). Analysis of the duration of GRB show that they are proportional to (1+z)(0.25±0.16). Both are consistent with no time dilation and inconsistent with a factor of (1+z) which implies that the universe is static. In addition it is shown that the standard method for calibrating the type Ia supernovae light curves (SALT2) is flawed, which explains why this lack of time dilation has not been previously observed.

 

[kurros]

I'm not a cosmologist, but my gut reaction from that abstract is that it is a load of garbage, especially that "this implies the universe is static" line. It seems implausible that people would have missed something like that until now, given that an awful lot of people have studied type Ia supernovae to death. I call BS :).

 

[kurros]

It seems like this guy has been on a bit of crusade to prove that the universe is static:

http://inspirehep.net/author/profile/D.F.Crawford.1

Doesn't look like he has many friends in that quest though. I also found this paper which makes the opposite conclusion to the OP, with a few famous names attached https://arxiv.org/abs/astro-ph/0504481. Not that science is about authority, but you know, people don't get famous in science by doing shoddy work.

 

[kimbyd]

Here is one for every one to pull apart, it goes beyond every thing I have learnt.

arXiv:1804.10274 [pdf, other]
Lack of time dilation in type Ia supernovae and Gamma-Ray Bursts
David F. Crawford
Comments: 4 pages, 2 figures and 1 table
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

A fundamental property of any expanding universe is that any time dependent characteristics of distant objects must appear to scale by the factor (1+z). This is called time dilation. Light curves of type Ia supernovae and the duration of Gamma-Ray Bursts (GRB) are the only observations that can directly measure time dilation over a wide range of redshifts. An analysis of raw observations of type Ia supernovae light curves shows that their widths are proportional to (1+z)(0.088±0.036). Analysis of the duration of GRB show that they are proportional to (1+z)(0.25±0.16). Both are consistent with no time dilation and inconsistent with a factor of (1+z) which implies that the universe is static. In addition it is shown that the standard method for calibrating the type Ia supernovae light curves (SALT2) is flawed, which explains why this lack of time dilation has not been previously observed.

I'd have to spend a fair amount of time to determine if this is true or not, but my initial guess is that they used measurements of light curves which already corrected for the time dilation. Naturally you wouldn't expect to see any time dilation after they had already corrected for it.

I haven't yet verified if this is the case, though.

 

[kimbyd]

Indeed this is his problem. For the SALT2 method, the light curve fitting is described here:
https://www.aanda.org/articles/aa/full/2007/16/aa6930-06/aa6930-06.html

Note the statement immediately following Eq (1): "where p is the rest-frame time since the date of maximum luminosity in B-band (the phase)".

That statement is all we need to know: the time is rest-frame time. Time dilation is already factored out. So Crawford's result is the result of a supremely basic misunderstanding of the data.