CosmoCoffee Forum Index CosmoCoffee

 
 FAQFAQ   SearchSearch  MemberlistSmartFeed   MemberlistMemberlist    RegisterRegister 
   ProfileProfile   Log inLog in 
Arxiv New Filter | Bookmarks & clubs | Arxiv ref/author:

Using CosmoMC with PPF module and usew0wa=F
 
Post new topic   Reply to topic    CosmoCoffee Forum Index -> Computers and software
View previous topic :: View next topic  
Author Message
Sunny Vagnozzi



Joined: 15 Aug 2016
Posts: 38
Affiliation: Oskar Klein Centre, Stockholm University

PostPosted: March 23 2017  Reply with quote

Dear Antony,

apologies for what might be a trivial question...

I am trying to use CosmoMC to get constraints on cosmological parameters in the presence of dark energy with a certain equation of state evolving with redshift/scale factor w(a). So in camb/params.ini I set
usew0wa = F
and then supply a file wa.dat with 2 columns: a=1/(1+z), and w(a)

My question is whether CosmoMC supports this type of user-provided dark energy equation of state? I recall reading in this post http://cosmocoffee.info/viewtopic.php?t=2342&sid=85eefe8deb274285b423b21bfb015f9f that CosmoMC does not support tabulated w(a) so I was wondering how to get around this

Cheers,
Sunny
Back to top
View user's profile  
Antony Lewis



Joined: 23 Sep 2004
Posts: 1274
Affiliation: University of Sussex

PostPosted: March 23 2017  Reply with quote

Yes, that's not supported by default - you'd need to modify it to do that.
Back to top
View user's profile [ Hidden ] Visit poster's website
Sunny Vagnozzi



Joined: 15 Aug 2016
Posts: 38
Affiliation: Oskar Klein Centre, Stockholm University

PostPosted: March 24 2017  Reply with quote

Dear Antony,

thanks for your reply. I was wondering whether for implementing more complicated equations of state, assuming I have an analytical expression for w(z) which might or might not depend on other cosmological parameters as well (e.g. in models where neutrinos are playing a role in the late-time acceleration?), it is possible to modify lines 97−98 in camb/equations_ppf.f90, which read
if(.not. use_tabulated_w) then
w_de=w_lam+wa_ppf*(1._dl-a)


Assuming I want to implement a parametrization with more than two parameters, would I have to make additional changes to the code, and where?

Cheers,
Sunny
Back to top
View user's profile  
Antony Lewis



Joined: 23 Sep 2004
Posts: 1274
Affiliation: University of Sussex

PostPosted: March 24 2017  Reply with quote

Yes, something like that should work. If it's quintessence you might want to use equations.f90 rather than the ppf approximation.

For adding parameters see the FAQ answer:
http://cosmologist.info/cosmomc/readme.html#FAQ
Back to top
View user's profile [ Hidden ] Visit poster's website
Display posts from previous:   
Post new topic   Reply to topic    CosmoCoffee Forum Index -> Computers and software All times are GMT + 5 Hours
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group. Sponsored by WordWeb online dictionary and dictionary software.