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Partition functions of probability distributions are important quantities for model evaluation and comparisons. We present a new method to compute partition functions of complex and multimodal distributions. Such distributions are often…

Machine Learning · Statistics 2016-05-27 David Carlson , Patrick Stinson , Ari Pakman , Liam Paninski

We use the COMPLETE Survey's observations of the Perseus star-forming region to assess and intercompare three methods for measuring column density in molecular clouds: extinction mapping (NIR); thermal emission mapping (FIR); and mapping…

Astrophysics · Physics 2011-02-11 Alyssa A. Goodman , Jaime E. Pineda , Scott L. Schnee

Measuring the temperature and abundance patterns of clouds in the interstellar medium (ISM) provides an observational basis for models of the physical conditions within the clouds, which play an important role in studies of star and planet…

Astrophysics of Galaxies · Physics 2019-06-26 Nicholas Kruczek , Kevin France , Keri Hoadley , Brian Fleming , Nicholas Nell

In this review, I discuss recent detailed studies of individual molecular clouds in M33 in higher rotational transitions of CO, 13CO, and the fine structure line of atomic carbon. These data reveal that the temperature and density of the…

Astrophysics · Physics 2007-05-23 C. D. Wilson

The analysis of X-ray and Sunyaev-Zel\'dovich measurements of the intracluster medium (ICM) assumes that electrons are in thermal equilibrium with ions in the plasma. However, electron-ion equilibration timescales can be comparable to the…

Cosmology and Nongalactic Astrophysics · Physics 2015-08-20 Camille Avestruz , Daisuke Nagai , Erwin T. Lau , Kaylea Nelson

Aims: Our aim is to identify the dominant molecular cooling lines and characteristic emission features in the 1.3 mm window of distinct regions in the northern part of the Orion A molecular cloud. By defining and analysing template regions,…

Astrophysics of Galaxies · Physics 2020-04-15 N. Brinkmann , F. Wyrowski , J. Kauffmann , D. Colombo , K. M. Menten , X. D. Tang , R. Güsten

By including the most recent observations of HI 21-cm absorption through near-by galactic disks, we confirm our previous assertion that there is an anti-correlation between the abundance of cool neutral atomic gas and impact parameter.…

Astrophysics of Galaxies · Physics 2020-04-01 S. J. Curran

We present high resolution (R = 75,000-100,000) mid-infrared spectra of the high-mass embedded young star IRS 1 in the NGC 7538 star-forming region. Absorption lines from many rotational states of C2H2, 13C12CH2, CH3, CH4, NH3, HCN, HNCO,…

Astrophysics of Galaxies · Physics 2012-08-27 C. Knez , J. H. Lacy , N. J. Evans , II , E. F. van Dishoeck , M. J. Richter

This is the first in a series of three papers describing a project with the Cosmic Origins Spectrograph on the Hubble Space Telescope to measure abundances of the neutral interstellar medium (ISM) in a sample of 9 nearby star-forming…

Astrophysics of Galaxies · Physics 2015-06-22 Bethan L. James , Alessandra Aloisi , Timothy M. Heckman , Sangmo Tony Sohn , Michael A. Wolfe

Aims. The purpose of this study is to investigate the distributions of the isomeric molecules HCN and HNC and estimate their abundance ratio in the protostellar core Cha-MMS1 located in Chamaeleon {\sc i}. Methods. The core was mapped in…

Astrophysics · Physics 2009-11-11 P. P. Tennekes , J. Harju , M. Juvela , L. V. Toth

The charged component of the insterstellar medium consists of atomic and molecular ions, electrons, and charged dust grains, coupled to the local Galactic magnetic field. Collisions between neutral particles (mostly atomic or molecular…

Astrophysics · Physics 2009-11-13 Cecilia Pinto , Daniele Galli

Infrared dark clouds (IRDCs) are cold and dense reservoirs of gas potentially available to form stars. Many of these clouds are likely to be pristine structures representing the initial conditions for star formation. The study presented…

The 14N/15N ratio in molecules exhibits a large variation in star-forming regions, especially when measured from N2H+ isotopologues. However, there are only a few studies performed at high-angular resolution. We present the first…

Astrophysics of Galaxies · Physics 2021-03-31 F. Fontani , A. T. Barnes , P. Caselli , J. D. Henshaw , G. Cosentino , I. Jiménez-Serra , J. C. Tan , J. E. Pineda , C. Y. Law

We use spectra and maps of the $J=1-0$ and $J=2-1$ DCO$^{+}$, DCN, DNC, $\rm N_2D^+$ lines and $1_{11}-1_{01}$ ortho- and para-NH$_{2}$D lines, obtained with the IRAM-30m telescope, as well as observations of their hydrogenated…

Astrophysics of Galaxies · Physics 2023-10-03 A. G. Pazukhin , I. I. Zinchenko , E. A. Trofimova , C. Henkel , D. A. Semenov

Volume density is a key physical quantity controlling the evolution of the interstellar medium (ISM) and star formation, but it cannot be accessed directly by observations of molecular clouds. We aim at estimating the volume density…

Astrophysics of Galaxies · Physics 2025-05-15 Jan H. Orkisz , Jouni Kainulainen

Based on measurements with the Effelsberg 100-m telescope, a multi-line study of molecular species is presented toward the gravitational lens system PKS1830-211. Obtaining average radial velocities and performing Large Velocity Gradient…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 C. Henkel , K. M. Menten , M. T. Murphy , N. Jethava , V. V. Flambaum , J. A. Braatz , S. Muller , J. Ott , R. Q. Mao

We analyze circumgalactic medium (CGM) in a suite of high-resolution cosmological re-simulations of a Milky-Way size galaxy and show that CGM properties are quite sensitive to details of star formation--feedback loop modelling. The…

Astrophysics of Galaxies · Physics 2016-03-09 Cameron J. Liang , Andrey V. Kravtsov , Oscar Agertz

There is a robust polyatomic chemistry in diffuse, partially-molecular interstellar gas that is readily accessible in absorption at radio/mm/sub-mm wavelengths. Accurate column densities are derived owing to the weak internal excitation, so…

Astrophysics of Galaxies · Physics 2023-02-15 Harvey Liszt , Maryvonne Gerin

We use a high-temperature chemical network to derive the molecular abundances in axisymmetric accretion disk models around active galactic nuclei (AGNs) within 100 pc using simple radial and vertical density and temperature distributions…

Astrophysics of Galaxies · Physics 2015-06-12 Nanase Harada , Todd A. Thompson , Eric Herbst

Full $NVT$ quantum statistics of the H$_3^+$ ion is simulated at low densities using the path integral Monte Carlo approach. For the first time, the molecular total energy, partition function, free energy, entropy and heat capacity are…

Earth and Planetary Astrophysics · Physics 2011-03-22 Ilkka Kylänpää , Tapio T. Rantala