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We discuss a new technique of studying magnetic fields in diffuse astrophysical media, e.g. interstellar and intergalactic gas/plasma. This technique is based on the angular momentum alignment of atoms and ions in their ground or metastable…

Astrophysics · Physics 2008-06-24 Huirong Yan , A. Lazarian

Observational studies of magnetic fields are vital as magnetic fields play a crucial role in various astrophysical processes, including star formation, accretion of matter, transport processes (e.g., transport of heat), and cosmic rays. We…

Astrophysics of Galaxies · Physics 2015-06-04 Huirong Yan , A. Lazarian

We show that atomic alignment presents a reliable way to study topology of astrophysical magnetic fields. The effect of atomic alignment arises from modulation of the relative population of the sublevels of atomic ground state pumped by…

Astrophysics · Physics 2008-11-26 Huirong Yan , A. Lazarian

Observational studies of magnetic fields are crucial. We introduce a process "ground state alignment" as a new way to determine the magnetic field direction in diffuse medium. The alignment is due to anisotropic radiation impinging on the…

Astrophysics of Galaxies · Physics 2013-02-15 Huirong Yan , A. Lazarian

Population of levels of the hyperfine and fine split ground state of an atom is affected by radiative transitions induced by anisotropic radiation flux. Such aligned atoms precess in the external magnetic field and this affects properties…

Astrophysics · Physics 2007-05-23 Huirong Yan , A. Lazarian

This article presents an introduction to optical pumping, atomic polarization and the Hanle effect in weakly magnetized stellar atmospheres. Although the physical processes and the theoretical framework described here are of interest for…

Astrophysics · Physics 2007-05-23 Javier Trujillo-Bueno

Magnetic fields play important roles in many astrophysical processes. However, there is no universal diagnostic for the magnetic fields in the interstellar medium (ISM) and each magnetic tracer has its limitation. Any new detection method…

Astrophysics of Galaxies · Physics 2017-12-19 Heshou Zhang , Huirong Yan

In this paper I will discuss new magnetic field diagnostics and instrumentation for an area of astrophysics where magnetic field observations have been difficult - circumstellar material. Such diagnostics would be particularly relevant to…

Astrophysics · Physics 2007-05-23 K. H. Nordsieck

The relative population of the fine structure sublevels of an atom's ground state is affected by radiative transitions induced by an anisotropic radiation flux. This causes the alignment of atomic angular momentum. In terms of observational…

Astrophysics · Physics 2008-11-26 Huirong Yan , A. Lazarian

Spectroscopic observations play essential roles in astrophysics. They are crucial for determining physical parameters in the universe, providing information about the chemistry of various astronomical environments. The proper execution of…

Astrophysics of Galaxies · Physics 2018-07-10 Heshou Zhang , Huirong Yan , Philipp Richter

Yan and Lazarian have proposed a new technique through which the magnetic field geometry in the diffuse interstellar medium, or in circumstellar matter, could be determined from the linear polarization of interstellar absorption or…

Astrophysics · Physics 2008-09-24 Kenneth Nordsieck

Spectroscopic observations play a fundamental role in astrophysics. They are crutial to determine important physical parameters, provide information about the composition of various objects in the universe, as well as depict motions in the…

Instrumentation and Methods for Astrophysics · Physics 2018-06-21 Heshou Zhang , Huirong Yan , Philipp Richter

The polarization of radiation by scattering on an atom embedded in combined external quadrupole electric and uniform magnetic fields is studied theoretically. Limiting cases of scattering under Zeeman effect and Hanle effect in weak…

Astrophysics · Physics 2015-06-24 Yee Yee Oo , M. Sampoorna , K. N. Nagendra , Sharath Ananthamurthy , G. Ramachandran

The polarization of radiation by scattering on an atom embedded in combined external quadrupole electric and uniform magnetic fields is studied theoretically. Analytic formulae are derived for the scattering phase matrix. Limiting cases of…

Astrophysics · Physics 2007-05-23 Yee Yee Oo , K. N. Nagendra , Sharath Ananthamurthy , G. Ramachandran

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

Magnetic fields play a role in the dynamics of many astrophysical processes, but they are hard to detect. In a partially ionized plasma, a magnetic field works directly on the ionized medium but not on the neutral medium, which gives rise…

Solar and Stellar Astrophysics · Physics 2020-06-24 Boy Lankhaar , Wouter Vlemmings

Atomic magnetometers are highly sensitive detectors of magnetic fields that monitor the evolution of the macroscopic magnetic moment of atomic vapors, and opening new applications in biological, physical, and chemical science. However, the…

Quantum Physics · Physics 2022-03-01 Min Jiang , Wenjie Xu , Qing Li , Ze Wu , Dieter Suter , Xinhua Peng

Atomic polarization phenomena impinge upon a number of areas and processes in physics. The dielectric constant and refractive index of any gas are examples of macroscopic properties that are largely determined by the dipole polarizability.…

Atomic Physics · Physics 2015-05-18 J. Mitroy , M. S. Safronova , Charles W. Clark

Polarized emission from polycyclic aromatic hydrocarbons (PAHs) potentially provides a new way to test basic physics of the alignment of ultrasmall grains. In this paper, we present a new model of polarized PAH emission that takes into…

Astrophysics of Galaxies · Physics 2017-04-12 Thiem Hoang

The alignment of interstellar dust grains with magnetic fields provides a key method for measuring the strength and morphology of the fields. In turn, this provides a means to study the role of magnetic fields from diffuse gas to dense…

Astrophysics of Galaxies · Physics 2016-02-09 John E. Vaillancourt , B-G Andersson
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