2007A&A...462..933C


C.D.S. - SIMBAD4 rel 1.7 - 2021.04.13CEST16:35:25

2007A&A...462..933C - Astronomy and Astrophysics, volume 462, 933-941 (2007/2-2)

Magnetic fields and ionized gas in nearby late type galaxies.

CHYZY K.T., BOMANS D.J., KRAUSE M., BECK R., SOIDA M. and URBANIK M.

Abstract (from CDS):

In order to analyze the importance of the star formation rate in generating and amplifying magnetic fields in the interstellar medium we perform a deep continuum polarization study of three angularly large, late type spiral galaxies. We obtained deep total power and polarization maps at 4.85GHz of NGC 4236, NGC 4656 and IC 2574 using the 100-m Effelsberg radio telescope. This was accompanied by imaging in the Hα line. We also observed these objects at 1.4GHz to obtain their integrated fluxes at this frequency and to determine their radio spectra. All galaxies were found to possess weak but detectable total power emission at 4.85GHz, coincident with regions of recent star formation as traced by bright Hα regions. The surface brightness of the radio-strongest object of our sample (NGC 4656) is comparable to the radio-weakest objects in a sample of more than 50 normally star-forming spiral galaxies for which measurements at 4.8GHz with the Effelsberg radio telescope are available. The surface brightness of the two other objects is even three times smaller. The fractional polarization of the 2 galaxies of our sample is less than 2%, significantly lower than for spiral galaxies of intermediate types, suggesting that the magnetic fields are not only weaker, but also less ordered than in spiral galaxies. The radio spectra of galaxies in our small sample are indicative of a substantial fraction of thermal emission, with a higher thermal fraction than in spirals with high star formation rates (SFR), while the nonthermal emission in our sample is relatively weak compared to spiral galaxies. We propose an equipartition model where the nonthermal emission increases ∝SFR∼1.4 and the ratio of nonthermal to thermal emission increases ∝SFR∼0.4. The objects of our sample still follow the radio-FIR correlation of surface brightness of the total emission, extending it towards the lowest values measured so far.

Abstract Copyright:

Journal keyword(s): galaxies: individual: NGC4236 - galaxies: individual: NGC4656 - galaxies: individual: IC2574 - galaxies: magnetic fields - radio continuum: galaxies - ISM: magnetic fields

Simbad objects: 15

goto Full paper

goto View the reference in ADS

Number of rows : 15

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 NGC 891 H2G 02 22 32.907 +42 20 53.95 11.08 10.81 9.93 7.86   ~ 1556 2
2 NAME M 81-82 Group GrG 09 55 +69.1           ~ 648 0
3 IC 2574 G 10 28 23.6204574649 +68 24 43.441365350 11.70 11.07 10.87 10.74   ~ 616 1
4 M 66 GiP 11 20 15.026 +12 59 28.64 9.85 9.65 8.92     ~ 1199 4
5 NGC 3628 GiP 11 20 17.018 +13 35 22.16   10.42 9.48 9.22   ~ 770 3
6 NGC 4236 GiG 12 16 42.118 +69 27 45.25 10.97 10.58 10.08 9.90   ~ 366 1
7 NGC 4256 GiP 12 18 43.0811197572 +65 53 53.752752601   12.7       ~ 75 0
8 M 99 H2G 12 18 49.625 +14 24 59.36 10.45 10.44 9.87     ~ 796 2
9 NGC 4565 LIN 12 36 20.804 +25 59 14.61   13.61 12.43     ~ 891 0
10 M 104 LIN 12 39 59.43185 -11 37 22.9954 9.51 9.55 8.00 8.05   ~ 1298 3
11 NGC 4631 GiP 12 42 08.009 +32 32 29.44   9.78 9.19 9.10   ~ 994 2
12 NGC 4656 GiP 12 43 57.6880843522 +32 10 13.343087893   10.96 10.52     ~ 330 3
13 3C 286 Sy1 13 31 08.2885060664 +30 30 32.960825108   17.51 17.25     ~ 3856 2
14 NGC 5906 GiG 15 15 53.687 +56 19 43.86   11.4       ~ 700 1
15 NGC 6822 G 19 44 56.199 -14 47 51.29   18 8.1     ~ 1457 0

    Equat.    Gal    SGal    Ecl

To bookmark this query, right click on this link: simbad:objects in 2007A&A...462..933C and select 'bookmark this link' or equivalent in the popup menu


2021.04.13-16:35:25

© Université de Strasbourg/CNRS

    • Contact