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We present a power spectrum analysis of the Herschel-SPIRE observations of the Polaris flare, a high Galactic latitude cirrus cloud midway between the diffuse and molecular phases. The SPIRE images of the Polaris flare reveal for the first…

We demonstrate the utility of the bispectrum, the Fourier three-point correlation function, for studying driving scales of magnetohydrodynamic (MHD) turbulence in the interstellar medium. We calculate the bispectrum by implementing a…

Astrophysics of Galaxies · Physics 2022-05-25 Michael J. O'Brien , Blakesley Burkhart , Michael J. Shelley

Magnetic turbulence is classified as weak or strong based on the relative amplitude of the magnetic field fluctuations compared to the mean field. These two classifications have different energy transport properties. This study analyzes…

Astrophysics of Galaxies · Physics 2024-11-13 Evangelia Ntormousi , Loukas Vlahos , Anna Konstantinou , Heinz Isliker

The Galactic interstellar turbulence affects the density distribution and star formation. We introduce a new method of measuring interstellar turbulent density spectra by using the dispersion measures (DMs) of a large sample of pulsars.…

Astrophysics of Galaxies · Physics 2021-01-06 Siyao Xu , Bing Zhang

It is shown that a number of key observations of the Galactic ISM can be understood, if it is treated as a highly compressible and turbulent medium energized predominantly by supernova explosions (and stellar winds). We have performed…

Astrophysics · Physics 2009-11-11 Dieter Breitschwerdt , Miguel A. de Avillez

We developed a mid-infrared optical frequency comb-based Fourier-transform spectrometer and performed a line-shape study of the fundamental vibrational band of CO perturbed by N${_2}$, which is crucial for atmospheric science and…

The circumgalactic medium (CGM) of nearby star-forming galaxies shows clear indications of OVI absorption accompanied by little to no detectable NV absorption. This unusual spectral signature, accompanied by highly non-uniform absorption…

Astrophysics of Galaxies · Physics 2020-07-01 Edward Buie , William J. Gray , Evan Scannapieco , Mohammadtaher Safarzadeh

The abundance of cold molecular gas plays a crucial role in models of galaxy evolution. While deep spectroscopic surveys of CO emission lines have been a primary tool for measuring this abundance, the difficulty of these observations has…

Astrophysics of Galaxies · Physics 2022-03-30 Ryan P. Keenan , Garrett K. Keating , Daniel P. Marrone

Informed by LES data and resolvent analysis of the mean flow, we examine the structure of turbulence in jets in the subsonic, transonic, and supersonic regimes. Spectral (frequency-space) proper orthogonal decomposition is used to extract…

Fluid Dynamics · Physics 2018-11-28 Oliver T. Schmidt , Aaron Towne , Georgios Rigas , Tim Colonius , Guillaume A. Brès

Fourier analysis and power spectrum estimation of the cosmic microwave background anisotropy on an incompletely sampled sky developed by Gorski (1994) has been applied to the high-latitude portion of the 4-year COBE DMR 31.5, 53 and 90 GHz…

Astrophysics · Physics 2009-10-28 K. M. Gorski , A. J. Banday , C. L. Bennett , G. Hinshaw , A. Kogut , G. F. Smoot , E. L. Wright

Measurements of the energy spectrum and of the vortex-density fluctuation spectrum in superfluid turbulence seem to contradict each other. Using a numerical model, we show that at each instance of time the total vortex line density can be…

Other Condensed Matter · Physics 2014-11-05 Andrew W. Baggaley , Jason Laurie , Carlo F. Barenghi

Normal thermal fluctuations of the cell membrane have been studied extensively using high resolution microscopy and focused light, particularly at the peripheral regions of a cell. We use a single probe particle attached non-specifically to…

Biological Physics · Physics 2020-04-16 Rahul Vaippully , Vaibavi Ramanujan , Manoj Gopalakrishnan , Saumendra Bajpai , Basudev Roy

The interaction of optically emitting clouds with warm X-ray gas and hot, tenuous radio plasma in radio jet cocoons is modelled by 2D compressible hydrodynamic simulations. The initial setup is the Kelvin-Helmholtz instability at a contact…

Astrophysics · Physics 2008-11-26 Martin Krause , Paul Alexander

We present a 1.1mm emission map of the OMC1 region observed with AzTEC, a new large-format array composed of 144 silicon-nitride micromesh bolometers, that was in use at the James Clerk Maxwell Telescope (JCMT). These AzTEC observations…

Astrophysics of Galaxies · Physics 2012-09-17 Soyoung Youn , Sungeun Kim

Optical beams propagating through atmospheric turbulence undergo spatiotemporal intensity fluctuations that deviate significantly from an ideal Gaussian profile. In this work, we present a unified theoretical and experimental framework for…

Optics · Physics 2026-03-10 Shouvik Sadhukhan , C. S. Narayanamurthy

Using a set of 28 high resolution, high signal to noise ratio (S/N) QSO Ly-alpha absorption spectra, we investigate the non-Gaussian features of the transmitted flux fluctuations, and their effect upon the power spectrum of this field. We…

Astrophysics · Physics 2009-11-07 Priya Jamkhedkar , Long-Long Feng , Wei Zheng , David Kirkman , David Tytler , Li-Zhi Fang

We study the observable properties of compressible MHD turbulence covering different turbulence regimes, based on synthetic synchrotron observations arising from 3D MHD numerical simulations. Using the synchrotron emissivity and intensity,…

High Energy Astrophysical Phenomena · Physics 2022-12-07 Ru-Yue Wang , Jian-Fu Zhang , Alex Lazarian , Hua-Ping Xiao , Fu-Yuan Xiang

The observed structure function (SF) of rotation measure (RM) varies as a broken power-law function of angular scales. The systematic shallowness of its spectral slope is inconsistent with the standard Kolmogorov scaling. This motivates us…

Astrophysics of Galaxies · Physics 2016-06-24 Siyao Xu , Bing Zhang

Measurements of the optical turbulence profile above Siding Spring Observatory were conducted during 2005 and 2006. This effort was largely motivated by the need to predict the statistical performance of adaptive optics at Siding Spring.…

Instrumentation and Methods for Astrophysics · Physics 2015-06-11 Michael Goodwin , Charles Jenkins , Andrew Lambert

In this paper we present a detailed analysis of the Faraday depth (FD) spectrum and its clean components obtained through the application of the commonly used technique of Faraday rotation measure synthesis to analyze spectro-polarimetric…

Astrophysics of Galaxies · Physics 2019-11-21 Aritra Basu , Andrew Fletcher , S. A. Mao , Blakesley Burkhart , Rainer Beck , Dominic Schnitzeler