Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Constraining Extragalactic Background Light From TeV Blazars   Our goal is to research the upper limits on the extragalactic background
light (EBL). The upper limits on the extragalactic background light (EBL),
using the Fermi and very high energy (VHE) spectra recently observed in TeV
blazars, are presented. We use an assumption that the VHE intrinsic photon
index cannot be harder than the Fermi index measured by the Fermi-LAT. Totally,
these upper limits on the EBL are compatible with ones given by most of EBL
models. However, the models of high EBL density are denied by TeV blazars.

32
The categories of this paper are: atom-ph
20
The categories of this paper are: acc-phys
26
The categories of this paper are: bayes-an
0
The categories of this paper are: hep-ph
4
The categories of this paper are: cond-mat
9
The categories of this paper are: nlin
16
The categories of this paper are: stat
27
The categories of this paper are: comp-gas
31
The categories of this paper are: ao-sci
13
The categories of this paper are: quant-ph
2
The categories of this paper are: math
3
The categories of this paper are: physics
5
The categories of this paper are: gr-qc
11
The categories of this paper are: hep-lat
21
The categories of this paper are: adap-org
12
The categories of this paper are: nucl-th