scholarly journals Non-thermal radio supernova remnants of exiled Wolf–Rayet stars

2021 ◽  
Vol 502 (4) ◽  
pp. 5340-5355
Author(s):  
D M-A Meyer ◽  
M Pohl ◽  
M Petrov ◽  
L Oskinova
Keyword(s):  
Magnetic Field ◽  
Supernova Remnants ◽  
Supernova Explosion ◽  
High Mass ◽  
Mixing Efficiency ◽  
Thermal Radio ◽  
Thermal Radio Emission ◽  
Characteristic Features ◽  
Hydrodynamical Simulations ◽  
Circumstellar Medium

ABSTRACT A signification fraction of Galactic massive stars (${\ge}8\, \rm M_{\odot }$) 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 of a $35\, \mathrm{M}_{\odot }$ star evolving through a Wolf–Rayet phase and running with velocity 20 and $40\, \rm km\, \rm s^{-1}$, respectively. A $7\, \mu \rm G$ ambient magnetic field is sufficient to modify the properties of the expanding supernova shock front and in particular to prevent the formation of filamentary structures. Prior to the supernova explosion, the compressed magnetic field in the circumstellar medium stabilizes the wind/ISM contact discontinuity in the tail of the wind bubble. A consequence is a reduced mixing efficiency of ejecta and wind materials in the inner region of the remnant, where the supernova shock wave propagates. Radiative transfer calculations for synchrotron emission reveal that the non-thermal radio emission has characteristic features reflecting the asymmetry of exiled core-collapse supernova remnants from Wolf–Rayet progenitors. Our models are qualitatively consistent with the radio appearance of several remnants of high-mass progenitors, namely the bilateral G296.5+10.0 and the shell-type remnants CTB109 and Kes 17, respectively.

scholarly journals Wind nebulae and supernova remnants of very massive stars

2020 ◽  
Vol 493 (3) ◽  
pp. 3548-3564 ◽  
Author(s):  
D M-A Meyer ◽  
M Petrov ◽  
M Pohl
Keyword(s):  
Supernova Remnants ◽  
Galactic Plane ◽  
Massive Stars ◽  
Mass Loss Rate ◽  
Supernova Explosion ◽  
Bow Shock ◽  
High Mass ◽  
Fast Wind ◽  
High Mass Loss ◽  
Hydrodynamical Simulations

ABSTRACT A very small fraction of (runaway) massive stars have masses exceeding $60\!-\!70\, \rm M_{\odot }$ and are predicted to evolve as luminous blue variable and Wolf–Rayet stars before ending their lives as core-collapse supernovae. Our 2D axisymmetric hydrodynamical simulations explore how a fast wind ($2000\, \rm km\, \rm s^{-1}$) and high mass-loss rate ($10^{-5}\, \rm M_{\odot }\, \rm yr^{-1}$) can impact the morphology of the circumstellar medium. It is shaped as 100 pc-scale wind nebula that can be pierced by the driving star when it supersonically moves with velocity $20\!-\!40\, \rm km\, \rm s^{-1}$ through the interstellar medium (ISM) in the Galactic plane. The motion of such runaway stars displaces the position of the supernova explosion out of their bow shock nebula, imposing asymmetries to the eventual shock wave expansion and engendering Cygnus-loop-like supernova remnants. We conclude that the size (up to more than $200\, \rm pc$) of the filamentary wind cavity in which the chemically enriched supernova ejecta expand, mixing efficiently the wind and ISM materials by at least $10{{\ \rm per\ cent}}$ in number density, can be used as a tracer of the runaway nature of the very massive progenitors of such $0.1\, \rm Myr$ old remnants. Our results motivate further observational campaigns devoted to the bow shock of the very massive stars BD+43°3654 and to the close surroundings of the synchrotron-emitting Wolf–Rayet shell G2.4+1.4.

scholarly journals Powering central compact objects with a tangled crustal magnetic field

2020 ◽  
Vol 495 (2) ◽  
pp. 1692-1699 ◽  
Author(s):  
Konstantinos N Gourgouliatos ◽  
Rainer Hollerbach ◽  
Andrei P Igoshev
Keyword(s):  
Magnetic Field ◽  
Supernova Remnants ◽  
Initial Conditions ◽  
Supernova Explosion ◽  
Compact Objects ◽  
Dipole Field ◽  
Ohmic Dissipation ◽  
X Ray ◽  
Axisymmetric Structure ◽  
Central Compact Objects

ABSTRACT Central Compact Objects (CCOs) are X-ray sources with luminosity ranging between 1032 and 1034 erg s−1, located at the centres of supernova remnants. Some of them have been confirmed to be neutron stars. Timing observations have allowed the estimation of their dipole magnetic field, placing them in the range ∼1010–1011 G. The decay of their weak dipole fields, mediated by the Hall effect and Ohmic dissipation, cannot provide sufficient thermal energy to power their X-ray luminosity, as opposed to magnetars whose X-ray luminosities are comparable. Motivated by the question of producing high X-ray power through magnetic field decay while maintaining a weak dipole field, we explore the evolution of a crustal magnetic field that does not consist of an ordered axisymmetric structure, but rather comprises a tangled configuration. This can be the outcome of a non-self-excited dynamo, buried inside the crust by fallback material following the supernova explosion. We find that such initial conditions lead to the emergence of the magnetic field from the surface of the star and the formation of a dipolar magnetic field component. An internal tangled magnetic field of the order of 1014 G can provide sufficient Ohmic heating to the crust and power CCOs, while the dipole field it forms is approximately 1010 G, as observed in CCOs.

Super-critical column accretion on to strongly magnetized neutron stars in ULX pulsars

2020 ◽  
Vol 72 (1) ◽  
Author(s):  
Tomohisa Kawashima ◽  
Ken Ohsuga
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Neutron Stars ◽  
Dense Matter ◽  
High Density ◽  
High Mass ◽  
Hollow Cone ◽  
Radial Magnetic Field ◽  
Accretion Rates ◽  
Hydrodynamical Simulations

Abstract We carry out axisymmetric two-dimensional radiation hydrodynamical simulations of super-critical accretion columns on to strongly magnetized neutron stars. The effect of the strong magnetic field is taken into account by inhibiting the fluid motion across the radial magnetic field of the neutron stars. It is found that the high-density matter falls on to the neutron star along the sidewall of the column. Within the column, two high-density inflow regions shaped like a hollow cone are found for the case of extremely high mass accretion rates, ${\dot{M}}/(L_{\rm Edd}/c{\,}^2) \sim 5\times 10^{2}$, where $\dot{M}$, $L_{\rm Edd}$, and $c$ are the mass accretion rate on to the neutron star, the Eddington luminosity, and the speed of light, respectively. The less dense matter in the gap between the high density inflow regions is blown away via the radiative force. The resultant structure of the inflow looks like a triple hollow cone. Matter falls on to the neutron star only through the sidewall for the case of moderately high mass accretion rates, ${\dot{M}}/(L_{\rm Edd}/c{\,}^2)\, {\sim 3 \times 10^1}$. A low-density outflow fills the interior of the column. In this case, the inflow structure looks like a single hollow cone. Although the copious photons are generated in the inflow regions via a shock, the photons escape from the sidewall of the column and the radiation force does not prevent inflow. The resulting luminosity of the sidewall exceeds $\sim\! 30$ times the Eddington luminosity for neutron stars, which is consistent with the observed luminosity of ultra-luminous X-ray pulsars.

scholarly journals Formation pathway for lonely stripped-envelope supernova progenitors: implications for Cassiopeia A

2020 ◽  
Vol 499 (1) ◽  
pp. 1154-1171 ◽  
Author(s):  
Ryosuke Hirai ◽  
Toshiki Sato ◽  
Philipp Podsiadlowski ◽  
Alejandro Vigna-Gómez ◽  
Ilya Mandel
Keyword(s):  
Supernova Remnants ◽  
High Mass ◽  
Core Collapse ◽  
Recombination Energy ◽  
Formation Pathway ◽  
Stellar Radius ◽  
Cassiopeia A ◽  
The Core ◽  
Hydrodynamical Simulations ◽  
The Impact

ABSTRACT We explore a new scenario for producing stripped-envelope supernova progenitors. In our scenario, the stripped-envelope supernova is the second supernova of the binary, in which the envelope of the secondary was removed during its red supergiant phase by the impact of the first supernova. Through 2D hydrodynamical simulations, we find that ∼50–90 ${{\ \rm per\ cent}}$ of the envelope can be unbound as long as the pre-supernova orbital separation is ≲5 times the stellar radius. Recombination energy plays a significant role in the unbinding, especially for relatively high mass systems (≳18 M⊙). We predict that more than half of the unbound mass should be distributed as a one-sided shell at about ∼10–100 pc away from the second supernova site. We discuss possible applications to known supernova remnants such as Cassiopeia A, RX J1713.7−3946, G11.2−0.3, and find promising agreements. The predicted rate is ∼0.35–1${{\ \rm per\ cent}}$ of the core-collapse population. This new scenario could be a major channel for the subclass of stripped-envelope or type IIL supernovae that lack companion detections like Cassiopeia A.

Quiescent Non-thermal Radio Emission from Stellar Systems

1995 ◽  
Vol 12 (2) ◽  
pp. 174-179 ◽  
Author(s):  
Michelle C. Storey ◽  
R. G. Hewitt
Keyword(s):  
Magnetic Field ◽  
Radio Emission ◽  
Three Dimensional ◽  
Emission Region ◽  
Relativistic Electrons ◽  
Thermal Radio ◽  
T Tauri ◽  
Thermal Radio Emission ◽  
Magnetic Field Model ◽  
Gyrosynchrotron Emission

AbstractNon-thermal radio emission has been detected from dMe stars, RS CVn binaries and W T Tauri stars. Polarisation and intensity measurements of the quiescent (i.e. non-flaring) emission indicate that the emission is gyrosynchrotron emission from mildly relativistic electrons spiralling in a magnetic field. A three-dimensional dipole magnetic field model for the stellar field is presented and the quiescent gyrosynchrotron emission from such a model is calculated and compared with observations. The model can account for many phenomenological features of quiescent emission. Quantitative comparisons of model results with observations indicate that the electron distribution in the emission region may be a magnetic mirroring distribution.

scholarly journals A New View on Young Pulsars in Supernova Remnants: Slow, Radio-quiet & X-ray Bright

2000 ◽  
Vol 177 ◽  
pp. 699-702 ◽  
Author(s):  
E. V. Gotthelf ◽  
G. Vasisht
Keyword(s):  
Magnetic Field ◽  
Neutron Stars ◽  
Supernova Remnants ◽  
Simple Explanation ◽  
Crab Pulsar ◽  
Radio Pulsars ◽  
Substantial Fraction ◽  
Subsequent Evolution ◽  
X Ray ◽  
Field Decay

AbstractWe propose a simple explanation for the apparent dearth of radio pulsars associated with young supernova remnants (SNRs). Recent X-ray observations of young remnants have revealed slowly rotating (P∼ 10s) central pulsars with pulsed emission above 2 keV, lacking in detectable radio emission. Some of these objects apparently have enormous magnetic fields, evolving in a manner distinct from the Crab pulsar. We argue that these X-ray pulsars can account for a substantial fraction of the long sought after neutron stars in SNRs and that Crab-like pulsars are perhaps the rarer, but more highly visible example of these stellar embers. Magnetic field decay likely accounts for their high X-ray luminosity, which cannot be explained as rotational energy loss, as for the Crab-like pulsars. We suggest that the natal magnetic field strength of these objects control their subsequent evolution. There are currently almost a dozen slow X-ray pulsars associated with young SNRs. Remarkably, these objects, taken together, represent at least half of the confirmed pulsars in supernova remnants. This being the case, these pulsars must be the progenitors of a vast population of previously unrecognized neutron stars.

scholarly journals Magnetorotational Mechanism of Supernova Explosions - Results of 2D Simulations

1998 ◽  
Vol 11 (1) ◽  
pp. 376-376
Author(s):  
S.G. Moiseenko
Keyword(s):  
Magnetic Field ◽  
Equations Of State ◽  
Supernova Explosion ◽  
Neutrino Energy ◽  
Energy Losses ◽  
Rotational Momentum ◽  
Supernova Explosions ◽  
2D Numerical Simulation ◽  
Lagrangian Scheme ◽  
The Magnetic Field

Results of 2D numerical simulation of the magneto rotational mechanism of a supernova explosion are presented. Simulation has been done for the real equations of state and neutrino energy losses have been taken into account. Simulation has been done on the basis of an Implicit Lagrangian scheme on atriangular grid with grid reconstructuring. It is shown that, due to differential rotation of the star, a toroidal component of the magnetic field appears and grows with time. Rotational momentum transfers outwards as the toroidal component grows with time. With the evolution of the process, part of the envelope of the star is ejected. The amounts of the thrown-off mass and energy are estimated. The results of the simulation could be used as a possible explanation for the supernova explosion picture.

scholarly journals Constraining the coherence scale of the interstellar magnetic field using TeV gamma-ray observations of supernova remnants

2020 ◽  
Vol 496 (2) ◽  
pp. 2448-2461 ◽  
Author(s):  
Matteo Pais ◽  
Christoph Pfrommer ◽  
Kristian Ehlert ◽  
Maria Werhahn ◽  
Georg Winner
Keyword(s):  
Magnetic Field ◽  
Interstellar Medium ◽  
Supernova Remnants ◽  
Gamma Ray ◽  
Galactic Cosmic Rays ◽  
Shock Acceleration ◽  
Interstellar Gas ◽  
Narrow Angle ◽  
Magnetohydrodynamic Simulations ◽  
Tev Gamma Rays

ABSTRACT Galactic cosmic rays (CRs) are believed to be accelerated at supernova remnant (SNR) shocks. In the hadronic scenario, the TeV gamma-ray emission from SNRs originates from decaying pions that are produced in collisions of the interstellar gas and CRs. Using CR-magnetohydrodynamic simulations, we show that magnetic obliquity-dependent shock acceleration is able to reproduce the observed TeV gamma-ray morphology of SNRs such as Vela Jr and SN1006 solely by varying the magnetic morphology. This implies that gamma-ray bright regions result from quasi-parallel shocks (i.e. when the shock propagates at a narrow angle to the upstream magnetic field), which are known to efficiently accelerate CR protons, and that gamma-ray dark regions point to quasi-perpendicular shock configurations. Comparison of the simulated gamma-ray morphology to observations allows us to constrain the magnetic coherence scale λB around Vela Jr and SN1006 to $\lambda _B \simeq 13_{-4.3}^{+13}$ pc and $\lambda _B \gt 200_{-40}^{+50}$ pc, respectively, where the ambient magnetic field of SN1006 is consistent with being largely homogeneous. We find consistent pure hadronic and mixed hadronic-leptonic models that both reproduce the multifrequency spectra from the radio to TeV gamma-rays and match the observed gamma-ray morphology. Finally, to capture the propagation of an SNR shock in a clumpy interstellar medium, we study the interaction of a shock with a dense cloud with numerical simulations and analytics. We construct an analytical gamma-ray model for a core collapse SNR propagating through a structured interstellar medium, and show that the gamma-ray luminosity is only biased by 30 per cent for realistic parameters.

Resonance effects in thermal radio emission of water surface

1986 ◽  
Vol 29 (4) ◽  
pp. 279-283 ◽  
Author(s):  
V. E. Gershenzon ◽  
V. G. Irisov ◽  
Yu. G. Trokhimovskii ◽  
V. S. �tkin
Keyword(s):  
Radio Emission ◽  
Water Surface ◽  
Resonance Effects ◽  
Thermal Radio ◽  
Thermal Radio Emission

scholarly journals Low frequency radio counterparts of HESS J1731−347 a.k.a SNR G353.6−0.7

2017 ◽  
Vol 12 (S331) ◽  
pp. 201-205
Author(s):  
A. J. Nayana ◽  
Poonam Chandra
Keyword(s):  
Radio Emission ◽  
Radio Telescope ◽  
Supernova Remnants ◽  
Low Frequency ◽  
High Energy ◽  
Spectral Indices ◽  
Thermal Radio Emission ◽  
Very High Energy ◽  
Γ Rays ◽  
Very High

AbstractHESS J1731−347 a.k.a. SNR G353.6−0.7 is one of the five known very high energy (VHE, Energy > 0.1 TeV) shell-type supernova remnants. We carried out Giant Metrewave Radio Telescope (GMRT) observations of this TeV SNR in 1390, 610 and 325 MHz bands. We detected the 325 and 610 MHz radio counterparts of the SNR G353.6−0.7 (Nayana et al. 2017). We also determined the spectral indices of individual filaments and our values are consistent with the non-thermal radio emission. We compared the radio morphology with that of VHE emission. The peak in radio emission corresponds to the faintest feature in the VHE emission. We explain this anti-correlated emission in a possible leptonic origin of the VHE γ-rays.

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