INVESTIGATION OF DENSE GAS TOWARDS RELATIVISTIC OUTFLOW SOURCES

J Hawkes,P De Wilt,A Walsh,G Rowell,E De Oña-Wilhelmi,N Furukawa,A Kawamura,N Maxted,M Burton,T Hayakawa,Y Fukui,F Aharonian,B Dawson

doi:10.1142/s2010194514601987

Abstract

We probe the interstellar medium towards the objects Circinus X-1, a low-mass X-ray binary with relativistic jets; and the highly energetic Westerlund 2 stellar cluster, which is located towards TeV gamma-ray emission and interesting arc- and jet-like features seen in Nanten 12CO data. We have mapped both regions with the Mopra radio telescope, in 7 mm and 12 mm wavebands, looking for evidence of disrupted/dense gas caused by the interaction between high energy outflows and the ISM. Towards Westerlund 2, peaks in CS(J=1-0) emission indicate high density gas towards the middle of the arc and the endpoint of the jet; and radio recombination line emission is seen overlapping the coincident HII region RCW49. Towards Circinus X-1, 12CO(J = 1-0) Nanten data reveals three molecular clouds that lie in the region of Cir X-1. Gas parameters for each cloud are presented here.

Highlights

Circinus X-1 (Cir X-1) is a low-mass X-ray binary and microquasar, containing a young neutron star with an orbital period about its companion of ∼16.6 days.[1]
Arcminute-scale synchrotron X-ray lobes[4] and a 5 diameter radio nebula surrounding Cir X-1.1 Given the evidence of multi-TeV particle acceleration in the region, Cir X-1 is a good candidate for TeV gamma-ray (γ-ray) emission, no TeV γ-ray emission has been seen with H.E.S.S. (28 hrs).[5]
The cloud at −75 km/s appears to flank Supernova remnant (SNR) G321.9-0.3 and is broad ( 20 km/s FWHM), indicating the gas may be disrupted by the SNR which is at 5.5-6 kpc

Summary

Introduction

Circinus X-1 (Cir X-1) is a low-mass X-ray binary and microquasar, containing a young neutron star with an orbital period about its companion of ∼16.6 days.[1]. Arcminute-scale synchrotron X-ray lobes[4] and a 5 diameter radio nebula surrounding Cir X-1.1 Given the evidence of multi-TeV particle acceleration in the region, Cir X-1 is a good candidate for TeV gamma-ray (γ-ray) emission, no TeV γ-ray emission has been seen with H.E.S.S. Interesting arc- and jet-like features seen in Nanten 12CO data[6] towards the cluster may be an indication of relativistic particle acceleration in the region and may have a common origin with coincident TeV γ-ray source HESS J1023-575.7 Given the uncertainty in the origin of the TeV source and its link to the cluster, arc-jet feature and nearby pulsar PSR J1022-5746, a detailed picture of the dense and disrupted gas in this region is needed

Observations

Results

Conclusions