Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Uses and limitations of relativistic jet proper motions: lessons from
  galactic microquasars   It is shown that the two-sided jet proper motions observed from the galactic
microquasars GRS 1915+105 and GRO J1655-40 in practice only allow us to place
lower limits on the Lorentz factors of the outflows. As a consequence, it is
not possible to rule out the possibility that jets from X-ray binaries are just
as relativistic as those from active galactic nuclei (AGN). This results from
the fact that distance estimates place the sources, within uncertainties, at
the maximum distance d(max) which corresponds to an intrinsic velocity v=c. The
general case is explored, for a range of intrinsic Lorentz factors and angles
to the line of sight, and it is shown that a source of significantly
relativistic jets will nearly always be observed close to d(max) and as a
result it is unlikely that we will ever be able to measure with any accuracy
the Lorentz factor of a jet from two-sided proper motions. We will generally
not be able to do more than place a lower limit on the Lorentz factor of the
flow, and this limit is naturally even lower in the cases where we only observe
the approaching jet. On the other hand, under the assumption that any two-sided
jets we see are intrinsically relativistic, we can confidently place the source
at a distance d ~ d(max). As a result, observations of two-sided proper motions
in relativistic jets from AGN would be extremely important for calibration of
the cosmological distance scale. (ABRIDGED).

19
The categories of this paper are: eess
27
The categories of this paper are: comp-gas
4
The categories of this paper are: cond-mat
21
The categories of this paper are: adap-org
26
The categories of this paper are: bayes-an
31
The categories of this paper are: ao-sci
34
The categories of this paper are: chem-ph
14
The categories of this paper are: math-ph
20
The categories of this paper are: acc-phys
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The categories of this paper are: solv-int
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The categories of this paper are: chao-dyn
0
The categories of this paper are: hep-ph
9
The categories of this paper are: nlin
12
The categories of this paper are: nucl-th
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The categories of this paper are: econ
10
The categories of this paper are: q-bio