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Register a new userEars formation in Supernova Remnants: Overhearing an interaction history with bipolar circumstellar structures
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Added by
Alexandros Chiotellis
Publication date
2020
fields
Physics
and research's language is
English
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A characteristic feature that is frequently met in nearby supernova remnants (SNRs) is the existence of two antisymmetric, local protrusions that are projected as two ears in the morphology of the nebula. In this work, we present a novel scenario for the ear formation process according to which the two lobes are formed through the interaction of the SNR with a bipolar circumstellar medium (CSM) that was surrounding the explosion center. We conduct two dimensional hydrodynamic simulations and we show that the SNR shock breakout from the bipolar CSM triggers the inflation of two opposite protrusions at the equator of the remnant that retain their size and shape for several hundreds up to a few thousand years of the SNR evolution. We run a set of models by varying the supernova (SN) and CSM properties and we demonstrate that the extracted results reveal a good agreement with the observables, regarding the ears sizes, lifespan, morphology and kinematics. We discuss the plausibility of our model in nature and we suggest that the most likely progenitors of the ear-carrying SNRs are the Luminous Blue Variables or the Red/Yellow Supergiants for the SNRs resulted by core collapse SN events and the symbiotic binaries or the planetary nebulae for the remnants formed by Type Ia SNe. Finally, we compare our model with other ear formation models of the literature and we show that there are distinctive differences among them, concerning the ears orientation and the phase in which the ear formation process occurs.
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We present dust features and masses observed in young supernova remnants (SNRs) with Spitzer IRS mapping and staring observations of four youngest supernova remnants: SNR 1E102.2-7219 (E0102) in the SMC, Cas A and G11.2-0.3 in our Galaxy, and N132D in the LMC. The spectral mapping data revealed a number of dust features which include 21 micron-peak dust and featureless dust in Cas A and 18-micron peak dust in E0102 and N132D. The 18 micron-peak feature is fitted by a mix of MgSiO$_3$ and solid Si dust grains, while the 21-micron peak dust is by a mix of silicates and FeO; we also explore dust fitting using Continuous Distribution of Ellipsoid grain models. We report detection of CO fundamental band from Cas A in near-infrared. We review dust features observed and identified in other SNRs. The dust emission is spatially correlated with the ejecta emission, showing dust is formed in SN ejecta. The spectra of E0102 show rich gas lines from ejecta including strong ejecta lines of Ne and O, including two [Ne III] lines and two [Ne V] lines which allow us to diagnostic density and temperature of the ejecta and measure the ejecta masses. E0102 and N132D show weak or lacking Ar, Si, and Fe ejecta, whereas the young Galactic SNR Cas A show strong Ar, Si, and S and weak Fe. We discuss compositions and masses of dust and association with those of ejecta and finally, dust contribution from SNe to early Universe.
Supernova (SN) 2014C is a unique explosion where a seemingly typical hydrogen-poor stripped envelope SN started to interact with a dense, hydrogen-rich circumstellar medium (CSM) a few months after the explosion. The delayed interaction suggests a detached CSM shell, unlike in a typical SN IIn where the CSM is much closer and the interaction commences earlier post-explosion; indicating a different mass loss history. We present near- to mid-infrared observations of SN 2014C from 1-5 years after the explosion, including uncommon 9.7 $mu$m imaging with COMICS on the Subaru telescope. Spectroscopy shows that the interaction is still ongoing, with the intermediate-width He I 1.083 $mu$m emission present out to our latest epoch 1639 days post-explosion. The last Spitzer/IRAC photometry at 1920 days post-explosion further confirms ongoing CSM interaction. The 1-10 $mu$m spectral energy distributions (SEDs) can be explained by a dust model with a mixture of 69% carbonaceous and 31% silicate dust, pointing to a chemically inhomogeneous CSM. The inference of silicate dust is the first among interacting SNe. An SED model with purely carbonaceous CSM dust is possible, but would require more than 0.22 $M_{odot}$ of dust, which is an order of magnitude larger than what observed in any other SNe, measured in the same way, at this epoch. The light curve beyond 500 days is well fit by an interaction model with a wind-driven CSM and a mass loss rate of $sim 10^{-3} , M_{odot},rm yr^{-1}$, which presents an additional CSM density component exterior to the constant density shell reported previously in the literature. SN 2014C could originate in a binary system, similar to RY Scuti, which would explain the observed chemical and density profile inhomogeneity in the CSM.
Hydrogen-rich, core-collapse supernovae are typically divided into four classes: IIP, IIL, IIn, and IIb. In general, interaction with circumstellar material is only considered for Type IIn supernovae. However, recent hydrodynamic modeling of IIP and IIL supernovae requires circumstellar material to reproduce their early light curves. In this scenario, IIL supernovae experience large amounts of mass loss before exploding. We test this hypothesis on ASASSN-15oz, a Type IIL supernova. With extensive follow-up in the X- ray, UV, optical, IR, and radio we present our search for signs of interaction, and the mass-loss history indicated by their detection. We find evidence of short-lived intense mass-loss just prior to explosion from light curve modeling, amounting in 1.5 M$_{odot}$ of material within 1800 R$_{odot}$ of the progenitor. We also detect the supernova in the radio, indicating mass-loss rates of $10^{-6}-10^{-7}$ M$_{odot}$ yr$^{-1}$ prior to the extreme mass-loss period. Our failure to detect the supernova in the X-ray and the lack of narrow emission lines in the UV, optical, and NIR do not contradict this picture and place an upper limit on the mass-loss rate outside the extreme period of $<10^{-4}$ M$_{odot}$ yr$^{-1}$. This paper highlights the importance gathering comprehensive data on more Type II supernovae to enable detailed modeling of the progenitor and supernova which can elucidate their mass-loss histories and envelope structures and thus inform stellar evolution models.
Supernova remnants are known to accelerate cosmic rays (CRs) on account of their non-thermal emission of radio waves, X-rays, and gamma rays. However, the ability to accelerate CRs up to PeV-energies has yet to be demonstrated. The presence of cut-offs in the gamma-ray spectra of several young SNRs led to the idea that PeV energies might only be achieved during the very initial stages of a remnants evolution. We use the time-dependent acceleration code RATPaC to study the acceleration of cosmic rays in supernovae expanding into dense environments around massive stars, where the plentiful target material might offer a path to the detection of gamma-rays by current and future experiments. We performed spherically symmetric 1-D simulations in which we simultaneously solve the transport equations for cosmic rays, magnetic turbulence, and the hydrodynamical flow of the thermal plasma in the test-particle limit. We investigated typical parameters of the circumstellar medium (CSM) in the freely expanding winds around red supergiant (RSG) and luminous blue variable (LBV) stars. The maximum achievable energy might be limited to sub-PeV energies despite strong magnetic fields close to the progenitor star that enhance turbulence-damping by cascading: we find a maximum CR energy of 100-200 TeV, reached within one month after explosion. The peak luminosity for a LBV progenitor is 1e43 erg/s (1e42 erg/s) at GeV (TeV) energies and, for a RSG progenitor, 1e41 erg/s (1e40 erg/s). All calculated SNe reach their peak gamma-ray luminosity after <~1 month and then fade at a rate ~1/t as long as the SN shock remains in the freely expanding wind of the progenitor. Potentially detectable gamma-ray signals can be expected in the Fermi-LAT waveband weeks to months after an explosion into a freely expanding wind.
As part of a systematic search programme of a 10-degree wide strip of the Northern Galactic plane we present preliminary evidence for the discovery of four (and possibly five) new supernova remnants (SNRs). The pilot search area covered the 19-20 hour right ascension zone sampling from +20 to +55 degrees in declination using binned mosaic images from the INT Photometric H-alpha Survey (IPHAS). The optical identification of the candidate SNRs was based mainly on their filamentary and arc-like emission morphologies, their apparently coherent, even if fractured structure and clear disconnection from any diffuse neighbouring HII region type nebulosity. Follow-up optical spectroscopy was undertaken, sampling carefully across prominent features of these faint sources. The resulting spectra revealed typical emission line ratios for shock excited nebulae which are characteristic of SNRs, which, along with the latest diagnostic diagrams, strongly support the likely SNR nature of these sources: G038.7-1.3 (IPHASX J190640.5+042819); G067.6+0.9 (IPHASX J195744.9+305306); G066.0-0.0 (IPHASX J195749.2+290259) and G065.8-0.5 (IPHASX J195920.4+283740). A fifth possible younger, higher density nebula SNR candidate, G067.8+0.5 (IPHASX J200002.4+305035) was discovered about 5 arcmins to the west of IPHASX J195744.9+305306, and warrants further study. A multi-wavelength cross-check from available archived data in the regions of these candidates was also performed with a focus on possible radio counterparts.
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