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Polarized infrared emission from polycyclic aromatic hydrocarbons (PAHs) is important for testing the basic physics of alignment of ultrasmall grains and potentially offers a new way to trace magnetic fields. In this paper, a new model of…

Astrophysics of Galaxies · Physics 2017-12-15 Thiem Hoang

We study the effect of anisotropic radiation illumination on the alignment of polycyclic aromatic hydrocarbons (PAHs) and report that cross-sectional mechanism of alignment earlier considered in terms of gas-grain interactions can also be…

Astrophysics of Galaxies · Physics 2018-07-11 Thiem Hoang , A. Lazarian

We study the polarized infrared emission by Polycyclic Aromatic Hydrocarbons (PAHs), when anisotropically illuminated by UV photons. PAH molecules are modeled as planar disks with in-plane and out-of-plane vibrational dipoles. As first…

Astrophysics of Galaxies · Physics 2011-02-11 Lorenzo Sironi , Bruce T. Draine

We present a new method to accurately describe the ionization fraction and the size distribution of polycyclic aromatic hydrocarbons (PAHs) within astrophysical sources. To this purpose, we have computed the mid-infrared emission spectra of…

Astrophysics of Galaxies · Physics 2020-03-18 A. Maragkoudakis , E. Peeters , A. Ricca

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in astrophysical environments, as revealed by their pronounced emission features at 3.3, 6.2, 7.7, 8.6, 11.3, and 12.7 $\mu$m commonly ascribed to the C--H and C--C vibrational modes.…

Astrophysics of Galaxies · Physics 2017-07-19 Han Zhang , Charles M. Telesco , Thiem Hoang , Aigen Li , Eric Pantin , Christopher M. Wright , Dan Li , Peter Barnes

Planck results have revealed that the electric dipole emission from polycyclic aromatic hydrocarbons (PAHs) is the most reliable explanation for anomalous microwave emission that interferes with cosmic microwave background (CMB) radiation…

Astrophysics of Galaxies · Physics 2015-06-15 Thiem Hoang , A. Lazarian , P. G. Martin

We present a charge distribution based model that computes the infrared spectrum of polycyclic aromatic hydrocarbon (PAH) molecules using recent measurements or quantum chemical calculations of specific PAHs. The model is applied to a…

Astrophysics of Galaxies · Physics 2022-06-15 Ameek Sidhu , A. G. G. M. Tielens , Els Peeters , Jan Cami

Polycyclic Aromatic Hydrocarbons (PAHs) are carbon-based molecules resulting from the union of aromatic rings and related species, which are likely responsible for strong infrared emission features (3.3, 6.2, 7.7, 8.6, 11.3 and 12.7…

Astrophysics of Galaxies · Physics 2021-11-05 I. García-Bernete , D. Rigopoulou , A. Alonso-Herrero , M. Pereira-Santaella , P. F. Roche , B. Kerkeni

[Abridged] The ionization of polycyclic aromatic hydrocarbons (PAHs), by ultraviolet (UV) photons from massive stars is expected to account for a large fraction of the heating of neutral gas in galaxies. Evaluation of this proposal,…

Astrophysics of Galaxies · Physics 2022-12-14 O. Berné , S. Foschino , F. Jalabert , C. Joblin

Magnetic dipole emission (MDE) from interstellar magnetic nanoparticles is an important Galactic foreground in the microwave frequencies, and its polarization level may pose great challenges for achieving reliable measurements of cosmic…

Astrophysics of Galaxies · Physics 2016-05-10 Thiem Hoang , A. Lazarian

Intensity ratios of aromatic emission features are widely used to diagnose the size and ionization state of polycyclic aromatic hydrocarbons (PAHs) in astronomical environments. However, PAHs are known to typically carry aliphatic side…

Astrophysics of Galaxies · Physics 2026-05-12 Zhuang Zhang , Yong Zhang

We present a novel method to measure the strength of interstellar magnetic fields based on ultraviolet (UV) polarization of starlight, which is in part produced by weakly aligned, small interstellar grains. We begin with calculating degrees…

Astrophysics of Galaxies · Physics 2016-05-10 Thiem Hoang , A. Lazarian , P. G. Martin

Polycyclic aromatic hydrocarbons (PAHs) are responsible for strong mid-IR emission features near star-forming regions. It is well known that low-metallicity environments exhibit weaker PAH emission, but it is not clear how the metallicity…

Astrophysics of Galaxies · Physics 2025-06-09 Congcong Zhang , Joelene Hales , Els Peeters , Jan Cami , Ameek Sidhu , Junfeng Zhen

Thermal dust polarization is a powerful tool to probe magnetic fields ($\textbf{B}$) and grain properties. However, a systematic study of the dependence of dust polarization on grain properties in protostellar environments is not yet…

Astrophysics of Galaxies · Physics 2024-03-14 Nguyen Chau Giang , Thiem Hoang

Our aim is to study the polarization of thermal dust emission to see if the alignment of grain by radiative torques could explain the observed relation between the degree of polarization and the intensity in dense cores. Predictions are…

Astrophysics · Physics 2009-11-11 V. -M. Pelkonen , M. Juvela , P. Padoan

Grain alignment by radiative torques (RATs) has been extensively studied for various environment conditions, including interstellar medium, dense molecular clouds, and accretion disks, thanks to significant progress in observational,…

Astrophysics of Galaxies · Physics 2015-06-22 Thiem Hoang , A. Lazarian

The structure of magnetic fields within protostellar disks may be studied via polarimetry provided that grains are aligned in respect to magnetic field within the disks. We explore alignment of dust grains by radiative torque in T Tauri…

Astrophysics · Physics 2009-11-11 Jungyeon Cho , A. Lazarian

We present a new method to decompose the emission features of polycyclic aromatic hydrocarbons (PAHs) from mid-infrared spectra using theoretical PAH templates in conjunction with modified blackbody components for the dust continuum and an…

Astrophysics of Galaxies · Physics 2018-06-26 Yanxia Xie , Luis C. Ho , Aigen Li , Jinyi Shangguan

We present a new methodology for simulating mid-infrared emission from polycyclic aromatic hydrocarbons (PAHs) in galaxy evolution simulations. To do this, we combine theoretical models of PAH emission features as they respond to varying…

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