A New Look at the Integrated Radio/Microwave Continuum Spectrum of Galactic Supernova Remnant Ic 443

Abstract

Recent observations of the microwave sky, by the space telescopes such as WMAP and Planck, have opened a new window into the analysis of continuum emission from supernova remnants (SNRs). In this paper, different emission models that can explain the characteristic shape of presently known integrated radio/microwave continuum spectrum of the Galactic SNR IC 443 are tested and discussed. In particular, the possibility that the slight bump in the integrated continuum of this remnant around 20 -70 GHz is genuine and that can be explained by the contribution of additional emission mechanism such as of spinning dust is emphasized. We find that adding a spinning dust component to the emission model improves the fit of the integrated spectrum of this SNR while, at the same time preserves the physically probable parameter values. Finally, models that include the high-frequency synchrotron bending of the IC 443 radio to microwave continuum are favored.

Investigating the high-frequency spectral features of SNRs Tycho, W44, and IC443 with the Sardinia Radio Telescope

“…In the case of IC443, Onić et al (2017) estimated a synchrotron cutoff frequency (148 ± 23 GHz) of an order of magnitude higher than what we found for W44, with the concurring presence of a significant dust emission bump at 20−70 GHz, which is confirmed by our observations at 21.4 GHz. We do not rule out the possibility that a dust emission component could also be present in the W44 SED (Génova-Santos et al 2017).…”

“…IC443 is a large (45 size) evolved SNR formed nearly 4,000 yrs ago (Troja et al 2008), and located at a distance of ∼1.5 kpc (Petre et al 1988). The presence of both diluted and dense gaseous environments surrounding the SN blast wave and the interaction of the SN shock with several atomic and molecular clouds, makes IC443 a very interesting system with which to assess the scenario of CRs acceleration in SNRs (Lee et al 2008, Tavani et al 2010, Onić et al 2017. Its location close to the Galactic anti-centre, which is relatively isolated from the confusing contamination by unrelated Galactic plane emission, also makes this SNR a suitable target for low resolution radio and gamma-ray observations (Planck Collaboration et al 2016, Tavani et al 2010).…”

“…The higher-frequency emission observed in IC443 above ∼150 GHz could instead be attributed to thermal dust emission form the dust grains that survived the shock (Planck Collaboration et al 2016). In Fig.4 (b), we present the spectral model of IC443 proposed by Onić et al (2017), based on least-squares fits (χ 2 /dof = 2.3) of integrated flux density measurements from Table 1 of Castelletti et al (2011), Table 1 of Gao et al (2011), Table 3 of Reich et al (2003) and microwave measurements from Table 3 of the Planck Collaboration et al (2016). The resulting SED is modeled by a synchrotron emission with an exponential cutoff at 148 ± 23 GHz and a normalisation constant of 161 ± 3 Jy, spinning dust emission (peaked at the frequency 28 ± 3 GHz) represented by the expression shown in Equation (5) by Onić et al (2017) and a high-frequency (> 140 GHz) thermal dust emission component.…”

A digital correlator upgrade for the Arcminute MicroKelvin Imager

“…Ivezić et al 2007 andCOS-MOS (e.g. Scoville et al 2007); monitoring of variable and transient radio sources such as supernovae, GRBs, quasars and X-ray binaries; observations of supernova remnants with reported anomalous microwave emission (AME) detections at low resolution (Génova-Santos et al 2017, Onić et al 2017, to test for the presence of AME at the angular scales measured by AMI. In each case, the new correlator has allowed AMI to operate more effectively in challenging radio source environments than was previously possible.…”

“…Communication between boards in each AMI array is achieved using an industry-standard 10 Gb Ethernet (10 GbE) network, with an off-the-shelf switch providing interconnect. This so-called "Packetized Correlator" architecture was pioneered by the CASPER group (Parsons et al 2008;Hickish et al 2016) and has been well proven at multiple radio-telescopes (Kocz et al 2015;Foley et al 2016;Nita et al 2016;Primiani et al 2016).…”