2014A&A...566A...5I


C.D.S. - SIMBAD4 rel 1.7 - 2019.11.17CET20:11:43

2014A&A...566A...5I - Astronomy and Astrophysics, volume 566A, 5-5 (2014/6-1)

Galactic interstellar turbulence across the southern sky seen through spatial gradients of the polarization vector.

IACOBELLI M., BURKHART B., HAVERKORN M., LAZARIAN A., CARRETTI E., STAVELEY-SMITH L., GAENSLER B.M., BERNARDI G., KESTEVEN M.J. and POPPI S.

Abstract (from CDS):

Radio synchrotron polarization maps of the Galaxy can be used to infer the properties of interstellar turbulence in the diffuse magneto-ionic medium (MIM). In this paper, we investigate the normalized spatial gradient of linearly polarized synchrotron emission (|∇P|/|P|) as a tracer of turbulence, the relationship of the gradient to the sonic Mach number of the MIM, and changes in morphology of the gradient as a function of Galactic position in the southern sky. We used data from the S-band Polarization All Sky Survey (S-PASS) to image the normalized spatial gradient of the linearly polarized synchrotron emission (|∇P|/|P|) in the entire southern sky at 2.3GHz. The spatial gradient of linear polarization reveals rapid changes in the density and magnetic fluctuations in the MIM due to magnetic turbulence as a function of Galactic position. We made comparisons of these data to ideal MHD numerical simulations. To constrain the sonic Mach number (Ms), we applied a high-order moments analysis to the observations and to the simulated diffuse, isothermal ISM with ideal magneto-hydrodynamic turbulence. We find that polarization gradient maps reveal elongated structures, which we associate with turbulence in the MIM. Our analysis indicates that turbulent MIM is in a generally transonic regime. This result for the turbulent regime is more general than the ones deduced by the analysis of electron density variation data, because it is based on the stochastic imprints of the Faraday rotation effect, which is also sensitive to the magnetic field fluctuations. Filamentary structures are seen with typical widths down to the angular resolution, and the observed morphologies closely match numerical simulations and, in some cases, Hα contours. The |∇P|/|P| intensity is found to be approximately log-normal distributed. No systematic variations in the sonic Mach number are observed as a function of Galactic coordinates, which is consistent with turbulence in the WIM, as inferred by the analysis of Hα data. We conclude that the sonic Mach number of the diffuse MIM appears to be spatially uniform towards the Galactic plane and the Sagittarius-Carina arm, but local variations induced by nearby extended objects are also found.

Abstract Copyright:

Journal keyword(s): ISM: general - ISM: magnetic fields - ISM: structure - radio lines: general - radio continuum: ISM

Simbad objects: 18

goto Full paper

goto View the reference in ADS

Number of rows : 18

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 NAME Per Arm PoG 03 30 +45.0           ~ 1197 0
2 NAME GUM Nebula ISM 07 43 -42.1           ~ 376 1
3 NAME Vela XYZ Rad 08 34.0 -45 50           ~ 1089 2
4 SNR G261.9+05.5 SNR 09 04 20 -38 42.0           ~ 36 2
5 NAME Antlia SNR SNR 10 44 -37.2           ~ 12 1
6 SNR G295.5+09.7 SNR 12 09 40 -52 25.0           ~ 250 1
7 NAME Centaurus A Sy2 13 25 27.61509104 -43 01 08.8056025   8.18 6.84 6.66   ~ 3896 3
8 NAME Car-Sgr Arm PoG 15 00 -40.0           ~ 412 1
9 NAME Loop I SR? 15 01 -38.7           ~ 321 2
10 NAME Lupus SN SNR 15 02 22.1 -42 05 49           SNIa 1181 1
11 * del Sco SB* 16 00 20.00528 -22 37 18.1431 1.30 2.20 2.32 2.36 2.49 B0.3IV 684 0
12 LBN 1099 HII 16 00.6 -22 56           ~ 15 0
13 LBN 006.00+24.73 HII 16 35 56.8 -12 43 05           ~ 51 0
14 * zet Oph Be* 16 37 09.5390545 -10 34 01.529471 1.73 2.58 2.56 2.46 2.50 O9.2IVnn 1708 2
15 NAME Gal Center reg 17 45 40.04 -29 00 28.1           ~ 11047 0
16 NAME G353-34 reg 20 25 -47.0           ~ 3 1
17 NAME Local Arm reg ~ ~           ~ 346 0
18 NAME Scutum Spiral Arm PoG ~ ~           ~ 256 0

    Equat.    Gal    SGal    Ecl

To bookmark this query, right click on this link: simbad:objects in 2014A&A...566A...5I and select 'bookmark this link' or equivalent in the popup menu


2019.11.17-20:11:43

© Université de Strasbourg/CNRS

    • Contact