Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: How to Distinguish between Cloudy Mini-Neptunes and
  Water/Volatile-Dominated Super-Earths   One of the most profound questions about the newly discovered class of
low-density super-Earths is whether these exoplanets are predominately
H2-dominated mini-Neptunes or volatile-rich worlds with gas envelopes dominated
by H2O, CO2, CO, CH4, or N2. Transit observations of the super-Earth GJ 1214b
rule out a cloud-free H2-dominated atmosphere, but are not able to determine
whether the lack of deep spectral features is due to high-altitude clouds or
the presence of a high mean molecular mass atmosphere. Here, we demonstrate
that one can unambiguously distinguish between cloudy mini-Neptunes and
volatile-dominated worlds based on the differences in the wing steepness and
relative depths of water absorption features in moderate-resolution NIR
transmission spectra (R~100). In a numerical retrieval study, we show for GJ
1214b that an unambiguous distinction between a cloudy H2-dominated atmosphere
and cloud-free H2 atmosphere will be possible if the uncertainties in the
spectral transit depth measurements can be reduced by a factor of ~3 compared
to the published HST WFC3 and VLT transit observations. We argue that the
required precision for the distinction may be achievable with currently
available instrumentation by stacking 10-15 transit observations. We provide a
scaling law that scales our quantitative results to other transiting
super-Earths and Neptunes such as HD 97658b, 55 Cnc e, and GJ 436b. The
analysis is performed using an improved version of our Bayesian atmospheric
retrieval framework. The new framework not only constrains the gas composition
and cloud/haze parameters, but also determines our confidence in having
detected molecules and cloud/haze species through Bayesian model comparison.
Using the Bayesian tool, we demonstrate quantitatively that the subtle transit
depth variation in the Berta et al. (2012) data is not sufficient to claim the
detection of water absorption.

4
The categories of this paper are: cond-mat
3
The categories of this paper are: physics
2
The categories of this paper are: math
13
The categories of this paper are: quant-ph
11
The categories of this paper are: hep-lat
21
The categories of this paper are: adap-org
9
The categories of this paper are: nlin
20
The categories of this paper are: acc-phys
7
The categories of this paper are: hep-th
12
The categories of this paper are: nucl-th
34
The categories of this paper are: chem-ph
1
The categories of this paper are: cs
27
The categories of this paper are: comp-gas
10
The categories of this paper are: q-bio
28
The categories of this paper are: alg-geom
5
The categories of this paper are: gr-qc