We present a radio polarization study of the supernova remnant CTB 80 based on images at 1420 MHz from the Canadian Galactic plane survey, at 2695 MHz from the Effelsberg survey of the Galactic plane, and at 4800 MHz from the Sino-German 6cm polarization survey of the Galactic plane. We obtained a rotation measure (RM) map using polarization angles at 2695 MHz and 4800 MHz as the polarization percentages are similar at these two frequencies. RM exhibits a transition from positive values to negative values along one of the shells hosting the pulsar PSR B1951+32 and its pulsar wind nebula. The reason for the change of sign remains unclear. We identified a partial shell structure, which is bright in polarized intensity but weak in total intensity. This structure could be part of CTB 80 or part of a new supernova remnant unrelated to CTB 80.
We examine the evolution and emission of the supernova remnant (SNR) CTB109 using three-dimensional magnetohydrodynamics simulations. The SNR evolves in a medium divided by a plane interface into two media with different densities and pressure equilibrium. Our results reveal that a remnant with the characteristics of CTB109 is formed provided the supernova (SN) explosion takes place in the less dense medium and also if the interstellar magnetic field (ISMF) is almost uniform. Finally, we conclude that the quasiparallel mechanism can explain the brightness synchrotron emission and the position …
Breaks in the radio spectra of supernova remnants (SNRs) reflect the maximum energy of either shock-accelerated electrons or - in the case of pulsar wind nebulae - of electrons injected by the central pulsar. Otherwise, the break may result from energy losses due to synchrotron aging or it is caused by energy-dependent diffusion. A spectral steepening of the plerionic SNR CTB87 at around 11 GHz was observed in the eighties, but a recent analysis of CTB87's energetic properties based on new radio data raised doubt on it. CTB87 consists of a central compact component surrounded by a diffuse cent…
We present direct images in the H$α$ and [SII]$λλ$6717,6731 $\textÅ$ lines of the Galactic Supernova Remnant G109.1-1.0 (CTB 109). We confirm that the filaments detected are the optical counterpart of the X-ray and radio supernova remnant due to their high [SII]/H$α$ line-ratios. We study for the first time the kinematics of the optical counterpart of SNR CTB 109 using the UNAM scanning Fabry-Perot interferometer PUMA. We estimate a systemic velocity of V$_{LSR}$=-50$\pm$6 km s$^{-1}$ for this remnant and an expansion velocity of V$_{exp}$=230$\pm$5 km s$^{-1}$. From this velocity value and ta…
We present a new millimeter CO-line observation towards supernova remnant (SNR) CTB 87, which was regarded purely as a pulsar wind nebula (PWN), and an optical investigation of a coincident surrounding superbubble. The CO observation shows that the SNR delineated by the radio emission is projectively covered by a molecular cloud (MC) complex at V$_{\rm {LSR}}$ = $-60$ to $-54$ km s$^{-1}$. Both the symmetric axis of the radio emission and the trailing X-ray PWN appear projectively to be along a gap between two molecular gas patches at $-58$ to $-57$ km s$^{-1}$. Asymmetric broad profiles of $^…
Three supernova remnants form the CTB 37 complex: CTB 37A (G348.5+0.1, associated with the TeV $γ$-ray source HESS J1714-385), CTB 37B (G348.7+0.3, associated with HESS J1713-381 and the magnetar CXOU J171405.7.381031), and G348.5-0.0. We use 21 cm HI absorption measurements to constrain the kinematic distances to these SNRs, which have not previously been determined well. We revise the kinematic distance for CTB 37A to be in the range 6.3 to 9.5 kpc (previously $\sim$11.3 kpc) because it is beyond the near 3-kpc arm and in front of the far side of the CO cloud at -145 km s$^{-1}$ towards $l$=…
Pulsar wind nebulae (PWNe) studies with the Chandra X-ray Observatory have opened a new window to address the physics of pulsar winds, zoom on their interaction with their hosting supernova remnant (SNR) and interstellar medium, and identify their powering engines. We here present a new 70 ks, plus an archived 18 ks, Chandra ACIS observation of the SNR CTB 87 (G74.9+1.2), classified as a PWN with unusual radio properties and poorly studied in X-rays. We find that the peak of the X-ray emission is clearly offset from the peak of the radio emission by ~100" and located at the southeastern edge o…
QUIJOTE scientific results -- XIII. Intensity and polarization study of supernova remnants in the QUIJOTE-MFI wide survey: CTB 80, Cygnus Loop, HB 21, CTA 1, Tycho and HB 9
Relations between radio surface brightness ($Σ$) and diameter ($D$) of supernova remnants (SNRs) are important in astronomy. In this paper, following the work Duric \& Seaquist (1986) at adiabatic phase, we carefully investigate shell-type supernova remnants at radiative phase, and obtain theoretical $Σ$-$D$ relation at radiative phase of shell-type supernova remnants at 1 GHz. By using these theoretical $Σ$-$D$ relations at adiabatic phase and radiative phase, we also roughly determine phases of some supernova remnant from observation data.
We evaluate the current status of supernova remnants as the sources of Galactic cosmic rays. We summarize observations of supernova remnants, covering the whole electromagnetic spectrum and describe what these obser- vations tell us about the acceleration processes by high Mach number shock fronts. We discuss the shock modification by cosmic rays, the shape and maximum energy of the cosmic-ray spectrum and the total energy budget of cosmic rays in and surrounding supernova remnants. Additionally, we discuss problems with supernova remnants as main sources of Galactic cosmic rays, as well as al…
A revised catalogue of 274 Galactic supernova remnants (SNRs) is presented, along with some simple statistics of their parameters. It is shown that the remnants that have recently been identified are generally faint, as is expected from the selection effects that apply to the identification of remnants.
NGC6946 is a high star formation rate face-on spiral galaxy that has hosted ten supernovae since 1917. Not surprisingly, a large number of supernova remnants and candidates have been identified either as optical nebulae with high [S II]:H$α$ line ratios (147) or as compact non-thermal radio sources (35). However, there are only seven overlaps between these two samples. Here, we apply [Fe II] 1.644 $μ$m emission as a new diagnostic to search for supernova remnants in an attempt to resolve this discrepancy. [Fe II] is expected to be relatively strong in the radiative shocks of supernova remnants…
The study of shell-type supernova remnants is a key science focus for the VERITAS TeV telescope array. Supernova remnants (SNRs) are widely considered to be the strongest candidate for the source of cosmic rays below the knee around 10^15 eV. This presentation will highlight new VERITAS results including new measurements of the spectra of Cas A and IC 443 and observations of the "Forbidden Velocity Wing" FVW 190.2+1.1. These results and their implications for the nature of the cosmic rays - hadronic or electronic - accelerated in the remnants will be discussed.
The spectra of high-energy protons and nuclei accelerated by supernova remnant shocks are calculated taking into account magnetic field amplification and Alfvenic drift for different types of SNRs during their evolution. The overall energy spectrum and elemental composition of cosmic rays after propagation through the Galaxy are found.
The study of supernova remnants and pulsar wind nebulae was one of the Key Science Projects for the first two years of VERITAS observations. VERITAS is an array of four imaging Cherenkov telescopes located at the Whipple Observatory in southern Arizona. Supernova remnants are widely considered to be the strongest candidate for the source of cosmic rays below the knee at around 10^15 eV. Pulsar wind nebulae are synchrotron nebulae powered by the spin-down of energetic young pulsars, and comprise one of the most populous very-high-energy gamma-ray source classes. This poster will summarize the r…
The origin of cosmic rays holds still many mysteries hundred years after they were first discovered. Supernova remnants have for long been the most likely sources of Galactic cosmic rays. I discuss here some recent evidence that suggests that supernova remnants can indeed efficiently accelerate cosmic rays. For this conference devoted to the Astronomical Institute Utrecht I put the emphasis on work that was done in my group, but placed in a broader context: efficient cosmic-ray acceleration and the im- plications for cosmic-ray escape, synchrotron radiation and the evidence for magnetic- field…
A compact complex of line emission filaments in the galactic plane has the appearance of those expected of an evolved supernova remnant though non-thermal radio and X-ray emission have not yet been detected. This optical emission line region has now been observed with deep imagery and both low and high-dispersion spectroscopy. Diagnostic diagrams of the line intensities from the present spectra and the new kinematical observations both point to a supernova origin. However, several features of the nebular complex still require an explanation within this interpretation.
A revised catalogue of Galactic supernova remnants (SNRs) is presented, along with some simple statistics of their properties. Six new SNRs have been added to the catalogue since the previous published version from 2014, and six entries have been removed, as they have been identified as HII regions, leaving the number of entries in the catalogue at 294. Some simple statistics of the remnants in the catalogue, and the selection effects that apply, are discussed, along with some recently proposed Galactic SNR candidates.
Here is considered the full evolution of a spherical supernova remnant. We start by calculating the early time ejecta dominated stage and continue through the different phases of interaction with the circumstellar medium, and end with the dissipation and merger phase. The physical connection between the phases reveals new results. One is that the blast wave radius during the adiabatic phase is significantly smaller than it would be, if one does notaccount for the blast wave interaction with the ejecta.
Core-collapse supernova remnants are the gaseous nebulae of galactic interstellar media (ISM) formed after the explosive death of massive stars. Their morphology and emission properties depend both on the surrounding circumstellar structure shaped by the stellar wind-ISM interaction of the progenitor star and on the local conditions of the ambient medium. In the warm phase of the Galactic plane (n = 1/cm3, T = 8000 K), an organised magnetic field of strength 7 microG has profound consequences on the morphology of the wind bubble of massive stars at rest. In this paper we show through 2.5D magn…
A signification fraction of Galactic massive stars (> 8Mo) are ejected from their parent cluster and supersonically sail away through the interstellar medium (ISM). The winds of these fast-moving stars blow asymmetric bubbles thus creating a circumstellar environment in which stars eventually die with a supernova explosion. The morphology of the resulting remnant is largely governed by the circumstellar medium of the defunct progenitor star. In this paper, we present 2D magneto-hydrodynamical simulations investigating the effect of the ISM magnetic field on the shape of the supernova remnants …
The set of supernova remnants (SNR) from Green's SNR catalog which are found in the VLA Galactic Plane Survey (VGPS) are the objects considered in this study. For these SNR, we extract and analyse HI absorption spectra in a uniform way and construct a catalogue of absorption spectra and distance determinations.
The X-ray emission from a supernova remnant is a powerful diagnostic of the state of its shocked plasma. The temperature and the emission measure are related to the energy of the explosion, the age of the remnant, and the density of the surrounding medium. Here we present the results of a study of the remnant population of the Small Magellanic Cloud. Progress in X-ray observations of remnants has resulted in a sample of 20 remnants in the Small Magellanic Clound with measured temperatures and emission measures. We apply spherically symmetric supernova remnant evolution models to this set of re…
Distances are found for four supernova remnants without previous distance measurements. H I spectra and H I channel maps are used to determine the maximum velocity of H I absorption for the four supernova remnants (SNRs). We examined $^{13}$CO emission spectra and channel maps to look for possible molecular gas associated with each SNR, but did not find any. The resulting distances for the SNRs are $3.5 \pm 0.2$ kpc (G24.7+0.6), $4.7 \pm 0.3$ kpc (G29.6+0.1), $4.1 \pm 0.5$ kpc (G41.5+0.4) and $4.5 \pm 0 .4 - 9.0 \pm 0.4$ kpc (G57.2+0.8).
A new law of motion for supernova remnant (SNR) which introduces the quantity of swept matter in the thin layer approximation is introduced. This new law of motion is tested on 10 years observations of SN1993J. The introduction of an exponential gradient in the surrounding medium allows to model an aspherical expansion. A weakly asymmetric SNR, SN1006, and a strongly asymmetric SNR, SN1987a, are modeled. In the case of SN1987a the three observed rings are simulated.
We report on new Australian Telescope Compact Array (ATCA) observations of SNR J0519-6902. The Supernova Remnant (SNR) is small in size (~8 pc) and exhibits a typical SNR spectrum of alpha = -0.53 +- 0.07, with steeper spectral indices found towards the northern limb of the remnant. SNR J0519-6902 contains a low level of radially orientated polarisation at wavelengths of 3 & 6 cm, which is characteristic of younger SNRs. A fairly strong magnetic field was estimated of ~171 microG. The remnant appears to be the result of a typical Type Ia supernovae, sharing many properties as another small and…
