Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: An extremely powerful long-lived superluminal ejection from the black
  hole MAXI J1820+070   Black holes in binary systems execute patterns of outburst activity where two
characteristic X-ray states are associated with different behaviours observed
at radio wavelengths. The hard state is associated with radio emission
indicative of a continuously replenished, collimated, relativistic jet, whereas
the soft state is rarely associated with radio emission, and never
continuously, implying the absence of a quasi-steady jet. Here we report radio
observations of the black hole transient MAXI J1820$+$070 during its 2018
outburst. As the black hole transitioned from the hard to soft state we
observed an isolated radio flare, which, using high angular resolution radio
observations, we connect with the launch of bi-polar relativistic ejecta. This
flare occurs as the radio emission of the core jet is suppressed by a factor of
over 800. We monitor the evolution of the ejecta over 200 days and to a maximum
separation of 10$''$, during which period it remains detectable due to in-situ
particle acceleration. Using simultaneous radio observations sensitive to
different angular scales we calculate an accurate estimate of energy content of
the approaching ejection. This energy estimate is far larger than that derived
from state transition radio flare, suggesting a systematic underestimate of jet
energetics.

12
The categories of this paper are: nucl-th
30
The categories of this paper are: q-alg
17
The categories of this paper are: q-fin
2
The categories of this paper are: math
32
The categories of this paper are: atom-ph
19
The categories of this paper are: eess
11
The categories of this paper are: hep-lat
35
The categories of this paper are: mtrl-th
3
The categories of this paper are: physics
14
The categories of this paper are: math-ph
31
The categories of this paper are: ao-sci
37
The categories of this paper are: supr-con
4
The categories of this paper are: cond-mat
1
The categories of this paper are: cs
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The categories of this paper are: hep-ex
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The categories of this paper are: hep-th