61 citations · 337 across the 40 of their papers we have counts for
30 papers · 1 filter
Resolving dense photodissociation regions: the structure of photochemical fronts in three-dimensional gas distributions
Brandt A. L. Gaches, Thomas G. Bisbas, Lothar Brendel +1
For decades, the Orion Bar has been the prototypical photodissociation region. Viewed nearly edge-on, it offers a unique window into the stratified chemical structure of the atomic…
Can diffuse X-rays be important in driving photoionisation in molecular clouds?
E. I. Makarenko, A. V. Ivlev, S. Bialy +5
The ionisation balance in molecular clouds is regulated by several ionising sources, including cosmic rays, X-rays, and ultraviolet radiation. Their relative importance depends on…
JWST Whirlpool Galaxy Treasury: Mid-Infrared Emission in M51 and its Relation to Gas Column and Star Formation
Mansi Padave, Karin M. Sandstrom, Daniel A. Dale +25
Using JWST/MIRI imaging of M51 in eight broadband filters, we investigate correlations of mid-infrared emission from polycyclic aromatic hydrocarbons (PAHs) and dust continuum with…
A HINSA view of cosmic-ray ionization in IC 348 and NGC 1333: evidence for a strong low-energy cosmic-ray disparity
Gan Luo, Marco Padovani, Daniele Galli +5
The cosmic-ray ionization rate (CRIR) is one of the fundamental parameters influencing the chemical and dynamical evolution of molecular clouds. Although observations in recent yea…
Complex organic molecules and cosmic ray ionisation rate towards the massive protostar Cepheus A HW2
Emma W. Nielsen, Anna Punanova, Eva Wirström +5
Cosmic rays (CRs) are important drivers for molecular chemistry in star-forming regions, and laboratory experiments have shown that CRs can stimulate the release of complex organic…
The impact of attenuation on cosmic-ray chemistry: I. Abundances and chemical calibrators in molecular clouds
Arghyadeb Roy, Brandt A. L. Gaches, Jonathan C. Tan
The chemistry of shielded molecular gas is primarily driven by energetic, charged particles dubbed cosmic rays (CRs), in particular those with energies under 1 GeV. CRs ionize mole…
High-energy astrochemistry in the molecular interstellar medium
Brandt A. L. Gaches, Serena Viti
In the past decade, there has been a significant shift in astrochemistry with a renewed focus on the role of non-thermal processes on the molecular interstellar medium, in particul…
JWST observations of cosmic-ray-excited H in Barnard 68: spatial variations and constraints on cosmic-ray attenuation
David A. Neufeld, Kedron Silsbee, Alexei V. Ivlev +9
We present James Webb Space Telescope (JWST) NIRSpec observations of the starless dark cloud Barnard 68 that reveal the spatially-resolved signature of cosmic-ray excited molecular…
The Colors of Ices: Measuring ice column density through photometry
Adam Ginsburg, Savannah R. Gramze, Matthew L. N. Ashby +8
Ices imprint strong absorption features in the near- and mid-infrared, but until recently they have been studied almost exclusively with spectroscopy toward small samples of bright…
Mapping CO Ice in a Star-Forming Filament in the 3 kpc Arm with JWST
Savannah Gramze, Adam Ginsburg, Nazar Budaiev +14
CO gas emission is a fundamental tool for measuring column density, but in cold, dark clouds, much of the CO is locked away in ice. We present JWST results from observations of a s…
The first detection of cosmic-ray excited H in interstellar space
Shmuel Bialy, Amit Chemke, David A. Neufeld +12
Stars and planets form within cold, dark molecular clouds. In these dense regions, where starlight cannot penetrate, cosmic rays (CRs) are the dominant source of ionization -- driv…
An analytic formalism to describe the - relationship in molecular clouds
Brandt A. L. Gaches
Context. Astrochemical modeling requires, as input, the effective column density of gas (or extinction) that attenuates an external, isotropic, far-ultraviolet radiation field. In…
Detection of Deuterated Hydrocarbon Nanoparticles in the Whirlpool Galaxy, M51
B. T. Draine, Karin Sandstrom, Daniel A. Dale +29
Deuteration of hydrocarbon material, including polycyclic aromatic hydrocarbons (PAHs), has been proposed to account for the low gas-phase abundances of D in the interstellar mediu…
An Investigation of Disk Thickness in M51 from H-alpha, Pa-alpha, and Mid-Infrared Power Spectra
Bruce G. Elmegreen, Daniela Calzetti, Angela Adamo +27
Power spectra (PS) of high-resolution images of M51 (NGC 5194) taken with the Hubble Space Telescope and the James Webb Space Telescope have been examined for evidence of disk thic…
The Resolved Structure of a Low Metallicity Photodissociation Region
Ilyse Y. Clark, Karin Sandstrom, Mark Wolfire +14
Photodissociation Regions (PDRs) are key to understanding the feedback processes that shape interstellar matter in galaxies. One important type of PDR is the interface between HII…
A Probabilistic Model to Estimate Number Densities from Column Densities in Molecular Clouds
Brandt A. L. Gaches, Michael Y. Grudić
Constraining the physical and chemical evolution of molecular clouds is essential to our understanding of star formation. These investigations often necessitate knowledge of some l…
A new analytic approach to infer the cosmic-ray ionization rate in hot molecular cores from HCO, NH, and CO observations
Gan Luo, Thomas G. Bisbas, Marco Padovani +1
The cosmic-ray ionization rate () is one of the key parameters in star formation, since it regulates the chemical and dynamical evolution of molecular clouds by ionizing molec…
Atacama Large Aperture Submillimeter Telescope (AtLAST) Science: Our Galaxy
Pamela Klaassen, Alessio Traficante, Maria T. Beltrán +38
As we learn more about the multi-scale interstellar medium (ISM) of our Galaxy, we develop a greater understanding for the complex relationships between the large-scale diffuse gas…
The Astrochemistry Low-energy Electron Cross-Section (ALeCS) database I. Semi-empirical electron-impact ionization cross-section calculations and ionization rates
Brandt A. L. Gaches, Tommaso Grassi, Stefan Vogt-Geisse +6
(Abridged) Electron-molecule interaction is a fundamental process in radiation-driven chemistry in space, from the interstellar medium to comets. Therefore, knowledge of interactio…
GMC Collisions As Triggers of Star Formation. IX. Chemical Evolution
Chia-Jung Hsu, Jonathan C. Tan, Jonathan Holdship +5
Collisions between giant molecular clouds (GMCs) have been proposed as a mechanism to trigger massive star and star cluster formation. To investigate the astrochemical signatures o…
The evolution of HCO in molecular clouds using a novel chemical post-processing algorithm
M. Panessa, D. Seifried, S. Walch +4
Modeling the chemistry of molecular clouds is critical to accurately simulating their evolution. To reduce computational cost, 3D simulations generally restrict their chemistry to…
Cosmic-ray-induced H line emission: Astrochemical modeling and implications for JWST observations
Brandt A. L. Gaches, Shmuel Bialy, Thomas G. Bisbas +3
Context: It has been proposed that H near-infrared lines may be excited by cosmic rays and allow for a determination of the cosmic-ray ionization rate in dense gas. One-dimensi…
The impact of cosmic-ray attenuation on the carbon cycle emission in molecular clouds
Brandt A. L. Gaches, Thomas G. Bisbas, Shmuel Bialy
Observations of the emission of the carbon cycle species (C, C+ CO) are commonly used to diagnose gas properties in the interstellar medium but are significantly sensitive to the c…
TIMES II: Investigating the Relation Between Turbulence and Star-forming Environments in Molecular Clouds
Hyeong-Sik Yun, Jeong-Eun Lee, Neal J. Evans +14
We investigate the effect of star formation on turbulence in the Orion A and Ophiuchus clouds using principal component analysis (PCA). We measure the properties of turbulence by a…