Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: New Results from the X-ray and Optical Survey of the Chandra Deep Field
  South: The 300ks Exposure   We present results from 300 ks of X-ray observations of the Chandra Deep
Field South. The field of the four combined exposures is now 0.1035 deg^2 and
we reach a flux limit of 10^{-16} erg s^{-1} cm^{-2} in the 0.5-2 keV soft band
and 10^{-15} erg s^{-1} cm^{-2} in the 2-10 keV hard band, thus a factor 2
fainter than the previous 120 ks exposure. The total catalogue is composed of
197 sources including 22 sources detected only in the hard band, 51 only in the
soft band, and 124 detected in both bands. We have now the optical spectra for
86 optical counterparts. We compute the total contribution to the X-ray
background in the 2-10 keV band, which now amounts to (1.45\pm 0.15)*10^{-11}
erg cm^{-2} s^{-1} deg^{-2} (after the inclusion of the ASCA sources to account
for the bright end) to a flux limit of 10^{-15} erg s^{-1} cm^{-2}. This
corresponds to 60-90% of the unresolved hard X-ray background (XRB), given the
uncertainties on its actual value.[ABRIDGED]

13
The categories of this paper are: quant-ph
5
The categories of this paper are: gr-qc
11
The categories of this paper are: hep-lat
3
The categories of this paper are: physics
32
The categories of this paper are: atom-ph
17
The categories of this paper are: q-fin
8
The categories of this paper are: hep-ex
29
The categories of this paper are: funct-an
35
The categories of this paper are: mtrl-th
0
The categories of this paper are: hep-ph
28
The categories of this paper are: alg-geom
27
The categories of this paper are: comp-gas
33
The categories of this paper are: plasm-ph
20
The categories of this paper are: acc-phys
21
The categories of this paper are: adap-org
4
The categories of this paper are: cond-mat