English
 
Help Privacy Policy Disclaimer
  Advanced SearchBrowse

Item

ITEM ACTIONSEXPORT

Released

Journal Article

Covariant decomposition of the non-linear galaxy number counts and their monopole

MPS-Authors
/persons/resource/persons133110

Schmidt,  Fabian
High Energy Astrophysics, MPI for Astrophysics, Max Planck Society;

External Resource
No external resources are shared
Fulltext (restricted access)
There are currently no full texts shared for your IP range.
Fulltext (public)
There are no public fulltexts stored in PuRe
Supplementary Material (public)
There is no public supplementary material available
Citation

Ginat, Y. B., Desjacques, V., Jeong, D., & Schmidt, F. (2021). Covariant decomposition of the non-linear galaxy number counts and their monopole. Journal of Cosmology and Astroparticle Physics, 2021(12): 031. doi:10.1088/1475-7516/2021/12/031.


Cite as: https://hdl.handle.net/21.11116/0000-0009-F7F1-0
Abstract
We present a fully non-linear and relativistically covariant expression for the observed galaxy density contrast. Building on a null tetrad tailored to the cosmological observer's past light cone, we find a decomposition of the non-linear galaxy over-density into manifestly gauge-invariant quantities, each of which has a clear physical interpretation as a cosmological observable. This ensures that the monopole of the galaxy over-density field (the mean galaxy density as a function of observed redshift) is properly accounted for. We anticipate that this decomposition will be useful for future work on non-linearities in galaxy number counts, for example, deriving the relativistic expression for the galaxy bispectrum. We then specialise our results to conformal Newtonian gauge, with a Hubble parameter either defined globally or measured locally, illustrating the significance of the different contributions to the observed monopole of the galaxy density.