Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A covariant and gauge-invariant analysis of cosmic microwave background
  anisotropies from scalar perturbations   We present a new, fully covariant and manifestly gauge-invariant expression
for the temperature anisotropy in the cosmic microwave background radiation
resulting from scalar perturbations. We pay particular attention to gauge
issues such as the definition of the temperature perturbation and the placing
of the last scattering surface. In the instantaneous recombination
approximation, the expression may be integrated up to a Rees-Sciama term for
arbitrary matter descriptions in flat, open and closed universes. We discuss
the interpretation of our result in the baryon-dominated limit using numerical
solutions for conditions on the last scattering surface, and confirm that for
adiabatic perturbations the dominant contribution to the anisotropy on
intermediate scales (the location of the Doppler peaks) may be understood in
terms of the spatial inhomogeneity of the radiation temperature in the baryon
rest frame. Finally, we show how this term enters the usual Sachs-Wolfe type
calculations (it is rarely seen in such analyses) when subtle gauge effects at
the last scattering surface are treated correctly.

7
The categories of this paper are: hep-th
23
The categories of this paper are: solv-int
25
The categories of this paper are: patt-sol
24
The categories of this paper are: dg-ga
26
The categories of this paper are: bayes-an
11
The categories of this paper are: hep-lat
22
The categories of this paper are: chao-dyn
35
The categories of this paper are: mtrl-th
1
The categories of this paper are: cs
4
The categories of this paper are: cond-mat
17
The categories of this paper are: q-fin
34
The categories of this paper are: chem-ph
19
The categories of this paper are: eess
21
The categories of this paper are: adap-org
37
The categories of this paper are: supr-con
31
The categories of this paper are: ao-sci