Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Scattering analysis of LOFAR pulsar observations   We measure the effects of interstellar scattering on average pulse profiles
from 13 radio pulsars with simple pulse shapes. We use data from the LOFAR High
Band Antennas, at frequencies between 110 and 190~MHz. We apply a forward
fitting technique, and simultaneously determine the intrinsic pulse shape,
assuming single Gaussian component profiles. We find that the constant $\tau$,
associated with scattering by a single thin screen, has a power-law dependence
on frequency $\tau \propto \nu^{-\alpha}$, with indices ranging from $\alpha =
1.50$ to $4.0$, despite simplest theoretical models predicting $\alpha = 4.0$
or $4.4$. Modelling the screen as an isotropic or extremely anisotropic
scatterer, we find anisotropic scattering fits lead to larger power-law
indices, often in better agreement with theoretically expected values. We
compare the scattering models based on the inferred, frequency dependent
parameters of the intrinsic pulse, and the resulting correction to the
dispersion measure (DM). We highlight the cases in which fits of extreme
anisotropic scattering are appealing, while stressing that the data do not
strictly favour either model for any of the 13 pulsars. The pulsars show
anomalous scattering properties that are consistent with finite scattering
screens and/or anisotropy, but these data alone do not provide the means for an
unambiguous characterization of the screens. We revisit the empirical $\tau$
versus DM relation and consider how our results support a frequency dependence
of $\alpha$. Very long baseline interferometry, and observations of the
scattering and scintillation properties of these sources at higher frequencies,
will provide further evidence.

0
The categories of this paper are: hep-ph
16
The categories of this paper are: stat
15
The categories of this paper are: nucl-ex
9
The categories of this paper are: nlin
36
The categories of this paper are: cmp-lg
14
The categories of this paper are: math-ph
2
The categories of this paper are: math
7
The categories of this paper are: hep-th
27
The categories of this paper are: comp-gas
28
The categories of this paper are: alg-geom
20
The categories of this paper are: acc-phys
21
The categories of this paper are: adap-org
13
The categories of this paper are: quant-ph
35
The categories of this paper are: mtrl-th
24
The categories of this paper are: dg-ga
19
The categories of this paper are: eess