Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Gravitational radiation from collisions at the speed of light: a
  massless particle falling into a Schwarzschild black hole   We compute spectra, waveforms, angular distribution and total gravitational
energy of the gravitiational radiation emitted during the radial infall of a
massless particle into a Schwarzschild black hole. Our fully relativistic
approach shows that (i) less than 50% of the total energy radiated to infinity
is carried by quadrupole waves, (ii) the spectra is flat, and (iii) the zero
frequency limit agrees extremely well with a prediction by Smarr. This process
may be looked at as the limiting case of collisions between massive particles
traveling at nearly the speed of light, by identifying the energy $E$ of the
massless particle with $m_0 \gamma$, $m_0$ being the mass of the test particle
and $\gamma$ the Lorentz boost parameter. We comment on the implications for
the two black hole collision at nearly the speed of light process, where we
obtain a 13.3% wave generation efficiency, and compare our results with
previous results by D'Eath and Payne.

19
The categories of this paper are: eess
13
The categories of this paper are: quant-ph
37
The categories of this paper are: supr-con
26
The categories of this paper are: bayes-an
33
The categories of this paper are: plasm-ph
4
The categories of this paper are: cond-mat
36
The categories of this paper are: cmp-lg
15
The categories of this paper are: nucl-ex
11
The categories of this paper are: hep-lat
21
The categories of this paper are: adap-org
17
The categories of this paper are: q-fin
9
The categories of this paper are: nlin
35
The categories of this paper are: mtrl-th
8
The categories of this paper are: hep-ex
3
The categories of this paper are: physics
18
The categories of this paper are: econ