Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: New Detections of Galactic Molecular Absorption Systems toward ALMA
  Calibrator Sources   We report on Atacama Large Millimeter/submillimeter Array (ALMA) detections
of molecular absorption lines in Bands 3, 6 and 7 toward four radio-loud
quasars, which were observed as the bandpass and complex gain calibrators. The
absorption systems, three of which are newly detected, are found to be Galactic
origin. Moreover, HCO absorption lines toward two objects are detected, which
almost doubles the number of HCO absorption samples in the Galactic diffuse
medium. In addition, high HCO to H13CO+ column density ratios are found,
suggesting that the interstellar media (ISM) observed toward the two
calibrators are in photodissociation regions, which observationally illustrates
the chemistry of diffuse ISM driven by ultraviolet (UV) radiation. These
results demonstrate that calibrators in the ALMA Archive are potential sources
for the quest for new absorption systems and for detailed investigation of the
nature of the ISM.

27
The categories of this paper are: comp-gas
3
The categories of this paper are: physics
11
The categories of this paper are: hep-lat
26
The categories of this paper are: bayes-an
1
The categories of this paper are: cs
18
The categories of this paper are: econ
17
The categories of this paper are: q-fin
14
The categories of this paper are: math-ph
36
The categories of this paper are: cmp-lg
29
The categories of this paper are: funct-an
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The categories of this paper are: q-alg
28
The categories of this paper are: alg-geom
31
The categories of this paper are: ao-sci
12
The categories of this paper are: nucl-th
2
The categories of this paper are: math
25
The categories of this paper are: patt-sol