Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: First Light Sources at the End of the Dark Ages: Direct Observations of
  Population III Stars, Proto-Galaxies, and Supernovae During the Reionization
  Epoch   The cosmic dark ages are the mysterious epoch during which the pristine gas
began to condense and ultimately form the first stars. Although these
beginnings have long been a topic of theoretical interest, technology has only
recently allowed the beginnings of observational insight into this epoch. Many
questions surround the formation of stars in metal-free gas and the history of
the build-up of metals in the intergalactic medium: (1) What were the
properties of the first stellar and galactic sources to form in pristine
(metal-free) gas? (2) When did the epoch of Population III (metal-free) star
formation take place and how long did it last? (3) Was the stellar initial mass
function dramatically different for the first stars and galaxies? These
questions are all active areas of theoretical research. However, new
observational constraints via the direct detection of Population III star
formation are vital to making progress in answering the broader questions
surrounding how galaxies formed and how the cosmological properties of the
universe have affected the objects it contains.

26
The categories of this paper are: bayes-an
16
The categories of this paper are: stat
18
The categories of this paper are: econ
30
The categories of this paper are: q-alg
21
The categories of this paper are: adap-org
4
The categories of this paper are: cond-mat
8
The categories of this paper are: hep-ex
10
The categories of this paper are: q-bio
22
The categories of this paper are: chao-dyn
2
The categories of this paper are: math
31
The categories of this paper are: ao-sci
28
The categories of this paper are: alg-geom
11
The categories of this paper are: hep-lat
20
The categories of this paper are: acc-phys
17
The categories of this paper are: q-fin
3
The categories of this paper are: physics