Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Axial gravitational waves in FLRW cosmology and memory effects   We show initial data for gravitational axial waves, that are twice
differentiable but which are not $C^{2}$. They generate wave pulses that
interact with matter in the radiation cosmological era. This forces the
radiation matter to rotate. This rotation is permanent - it persists after the
passage of the gravitational pulse. The observed inhomogeneities of the cosmic
microwave background radiation put a bound onto discontinuities of superhorizon
metric perturbations. We explicitly show that a class of smooth initial metrics
that are at least $C^{2}$ gives rise to gravitational wave pulses that do not
interact with the background during the radiation epoch.

23
The categories of this paper are: solv-int
2
The categories of this paper are: math
29
The categories of this paper are: funct-an
25
The categories of this paper are: patt-sol
10
The categories of this paper are: q-bio
31
The categories of this paper are: ao-sci
13
The categories of this paper are: quant-ph
37
The categories of this paper are: supr-con
15
The categories of this paper are: nucl-ex
28
The categories of this paper are: alg-geom
1
The categories of this paper are: cs
14
The categories of this paper are: math-ph
11
The categories of this paper are: hep-lat
22
The categories of this paper are: chao-dyn
8
The categories of this paper are: hep-ex
0
The categories of this paper are: hep-ph