Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The simultaneous spectrum of Sgr A* from 20cm to 1mm and the nature of
  the mm-excess   We report results from a multiwavelength campaign to measure the simultaneous
spectrum of the super-massive black hole candidate Sgr A* in the Galactic
Center from cm to mm-wavelengths using the VLA, BIMA, the Nobeyama 45m, and the
IRAM 30m telescopes. The observations confirm that the previously detected
mm-excess is an intrinsic feature of the spectrum of Sgr A*. The excess can be
interpreted as due to the presence of an ultra-compact component of
relativistic plasma with a size of a few Schwarzschild radii near the black
hole. If so, Sgr A* might offer the unique possibility to image the putative
black hole against the background of this component with future mm-VLBI
experiments.

33
The categories of this paper are: plasm-ph
7
The categories of this paper are: hep-th
24
The categories of this paper are: dg-ga
10
The categories of this paper are: q-bio
17
The categories of this paper are: q-fin
22
The categories of this paper are: chao-dyn
16
The categories of this paper are: stat
32
The categories of this paper are: atom-ph
9
The categories of this paper are: nlin
30
The categories of this paper are: q-alg
3
The categories of this paper are: physics
2
The categories of this paper are: math
14
The categories of this paper are: math-ph
29
The categories of this paper are: funct-an
13
The categories of this paper are: quant-ph
0
The categories of this paper are: hep-ph