The Galactic plane region near $\ell$ = 93$\degr$ - III. Multi-wavelength emission from SNR 3C 434.1

T. Foster

doi:doi:10.1051/0004-6361:20053344

Free access

Issue		A&A Volume 441, Number 3, October III 2005


Page(s)		1043 - 1054
Section		Interstellar and circumstellar matter
DOI		http://dx.doi.org/10.1051/0004-6361:20053344

A&A 441, 1043-1054 (2005)
DOI: 10.1051/0004-6361:20053344

The Galactic plane region near $\ell$ = 93 $\degr$

III. Multi-wavelength emission from SNR 3C 434.1

T. Foster^{1, 2}

¹ National Research Council of Canada, Herzberg Institute of Astrophysics, Dominion Radio Astrophysical Observatory, PO Box 248, Penticton, BC V2A 6J9, Canada
e-mail: Tyler.Foster@nrc-cnrc.gc.ca
² Dept. of Physics, University of Alberta, Edmonton, Alberta, T6G 2J1, Canada

(Received 30 April 2005 / Accepted 27 June 2005)

Abstract
New Canadian Galactic Plane Survey radio continuum, ROSAT X-ray, and optical line observations of supernova remnant (SNR) 3C 434.1 (G94.0+1.0) are presented. A radio spectrum of index $\alpha=0.4$ (where $S\propto \nu ^{-\alpha }$ ) confirms this SNR's emission signature as predominantly synchrotron, and suggests the SNR is in the Sedov expansion phase. The morphology of the remnant is compared in X-ray, optical, and radio continuum, and the brightest emission in all three wavelength regimes is from the eastern hemisphere of 3C 434.1, which marks where the SNR shock is interacting with the inside wall of its stellar wind bubble (SWB) home. The system is determined to be 4.5 kpc distant, residing in the Perseus Arm Spiral shock. From a deep H $\alpha$ mosaic of the region, $\lambda$ 656 nm H $\alpha$ line emission is observed that correlates well with radio synchrotron emission and anticorrelates with X-ray emission from the SNR. The origin of this optical emission is likely dense ( $n_{\rm e}=40$ cm^-3) cooling $\ion{H}{ii}$ from the wall of the SWB, where the SNR shock has penetrated and become radiative ( $v_{\rm s}\sim 100$ km s^-1). The X-ray spectrum of this SNR between 0.5 and 2.4 keV is well modelled by a single-temperature thermal plasma ( $T_{\rm e}=4.5\times10^{6}$ K, $n_{\rm e}=0.2$ cm^-3). The magnetic field of the bright radio synchrotron emission region is found (under the assumption of near equipartition) to be $B\sim 15$ $\mu$ G, a factor of 3 compression of the ambient ISM field (5 $\mu$ G). The westward extension of 3C 434.1 is the result of ongoing free expansion of the shock into the lower density interior of the SWB. I use multiwavelength observations to arrive at a unique solution for an interaction model of 3C 434.1 with the SWB, from which the age ( $t=25\,000$ yr) and mass ejected in the explosion ( $M_{\rm ej}=15.5$ $M_{\odot }$ ) are determined. I also find an initial blast-wave velocity of 1350 km s^-1, typical of type 1b SNe.