Bow Shocks from Radio Pulsars: Observations of the Guitar Nebula

International Astronomical Union Colloquium ◽

10.1017/s0252921100060474 ◽

2000 ◽

Vol 177 ◽

pp. 517-518

Author(s):

Shami Chatterjee ◽

James M. Cordes

Keyword(s):

Scaling Laws ◽

Bow Shock ◽

Optical Observations ◽

Analytic Model ◽

Radio Pulsars ◽

Pulsar Velocity ◽

Bow Shocks

AbstractWe present optical observations and radio non-detections of the bow shock nebula associated with the pulsar B2224+65 (the “Guitar Nebula”), and fit an analytic model to the observed bow shock to estimate its inclination and constrain other parameters (distance, pulsar velocity, ISM density). We also test scaling laws for bow shock parameters.

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Interaction between a pulsating jet and a surrounding disk wind

Astronomy and Astrophysics ◽

10.1051/0004-6361/201732031 ◽

2018 ◽

Vol 614 ◽

pp. A119 ◽

Cited By ~ 4

Author(s):

B. Tabone ◽

A. Raga ◽

S. Cabrit ◽

G. Pineau des Forêts

Keyword(s):

Numerical Simulations ◽

Large Scale ◽

Bow Shock ◽

Analytic Model ◽

Disk Wind ◽

Chemical Enrichment ◽

Internal Working ◽

Protostellar Jets ◽

Bow Shocks ◽

Shell Approximation

Context. The molecular richness of fast protostellar jets within 20–100 au of their source, despite strong ultraviolet irradiation, remains a challenge for the models investigated so far. Aim.We aim to investigate the effect of interaction between a time-variable jet and a surrounding steady disk wind, to assess the possibility of jet chemical enrichement by the wind, and the characteristic signatures of such a configuration. Methods. We have constructed an analytic model of a jet bow shock driven into a surrounding slower disk wind in the thin shell approximation. The refilling of the post bow shock cavity from below by the disk wind is also studied. An extension of the model to the case of two or more successive internal working surfaces (IWS) is made. We then compared this analytic model with numerical simulations with and without a surrounding disk wind. Results. We find that at early times (of order the variability period), jet bow shocks travel in refilled pristine disk wind material, before interacting with the cocoon of older bow shocks. This opens the possibility of bow shock chemical enrichment (if the disk wind is molecular and dusty) and of probing the unperturbed disk wind structure near the jet base. Several distinctive signatures of the presence of a surrounding disk wind are identified, in the bow shock morphology and kinematics. Numerical simulations validate our analytical approach and further show that at large scale, the passage of many jet IWS inside a disk wind produces a stationary V-shaped cavity, closing down onto the axis at a finite distance from the source.

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Systematic search for very-high-energy gamma-ray emission from bow shocks of runaway stars

Astronomy and Astrophysics ◽

10.1051/0004-6361/201630151 ◽

2018 ◽

Vol 612 ◽

pp. A12 ◽

Cited By ~ 7

Author(s):

◽

H. Abdalla ◽

A. Abramowski ◽

F. Aharonian ◽

F. Ait Benkhali ◽

...

Keyword(s):

Gamma Ray ◽

High Energy ◽

Bow Shock ◽

Systematic Search ◽

Upper Limits ◽

Very High Energy ◽

Bow Shocks ◽

Gamma Ray Emission ◽

Runaway Stars ◽

Very High

Context. Runaway stars form bow shocks by ploughing through the interstellar medium at supersonic speeds and are promising sources of non-thermal emission of photons. One of these objects has been found to emit non-thermal radiation in the radio band. This triggered the development of theoretical models predicting non-thermal photons from radio up to very-high-energy (VHE, E ≥ 0.1 TeV) gamma rays. Subsequently, one bow shock was also detected in X-ray observations. However, the data did not allow discrimination between a hot thermal and a non-thermal origin. Further observations of different candidates at X-ray energies showed no evidence for emission at the position of the bow shocks either. A systematic search in the Fermi-LAT energy regime resulted in flux upper limits for 27 candidates listed in the E-BOSS catalogue.Aim. Here we perform the first systematic search for VHE gamma-ray emission from bow shocks of runaway stars.Methods. Using all available archival H.E.S.S. data we search for very-high-energy gamma-ray emission at the positions of bow shock candidates listed in the second E-BOSS catalogue release. Out of the 73 bow shock candidates in this catalogue, 32 have been observed with H.E.S.S.Results. None of the observed 32 bow shock candidates in this population study show significant emission in the H.E.S.S. energy range. Therefore, flux upper limits are calculated in five energy bins and the fraction of the kinetic wind power that is converted into VHE gamma rays is constrained.Conclusions. Emission from stellar bow shocks is not detected in the energy range between 0.14 and 18 TeV.The resulting upper limits constrain the level of VHE gamma-ray emission from these objects down to 0.1–1% of the kinetic wind energy.

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Radial dependence of foreshock cavities: a case study

Annales Geophysicae ◽

10.5194/angeo-22-4143-2004 ◽

2004 ◽

Vol 22 (12) ◽

pp. 4143-4151 ◽

Cited By ~ 6

Author(s):

D. G. Sibeck ◽

K. Kudela ◽

T. Mukai ◽

Z. Nemecek ◽

J. Safrankova

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Field Strength ◽

Magnetic Field Strength ◽

Bow Shock ◽

Radial Dependence ◽

Energetic Ions ◽

Interplanetary Physics ◽

Bow Shocks

Abstract. We present a case study of Geotail, Interball-1, IMP-8, and Wind observations of density and magnetic field strength cavities excavated by the enhanced pressures associated with bursts of energetic ions in the foreshock. Consistent with theoretical predictions, the pressure of the energetic ions diminishes rapidly with upstream distance due to a decrease in the flux of energetic ions and a transition from near-isotropic to streaming pitch angle distributions. Consequently, the cavities can only be observed immediately upstream from the bow shock. A comparison of conditions upstream from the pre- and post-noon bow shock demonstrates that foreshock cavities introduce perturbations into the oncoming solar wind flow with dimensions smaller than those of the magnetosphere. Dayside geosynchronous magnetic field strength variations observed by GOES-8 do not track the density variations seen by any of the spacecraft upstream from the bow shock in a one-to-one manner, indicating that none of these spacecraft observed the precise sequence of density variations that actually struck the subsolar magnetopause. Key words. Interplanetary physics (energetic particles; planetary bow shocks) – Magnetospheric physics (solar wind-magnetosphere interactions)

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Variations and Effects of the Venusian Bow Shock from VEX Mission

Proceedings of the International Astronomical Union ◽

10.1017/s1743921313013100 ◽

2012 ◽

Vol 8 (S293) ◽

pp. 329-332

Author(s):

Yansong Xue ◽

Shuanggen Jin

Keyword(s):

Solar Wind ◽

Solar Maximum ◽

Direct Interaction ◽

Magnetic Pressure ◽

Bow Shock ◽

Bow Shocks ◽

Venus Express ◽

Inner Region ◽

Planetary Magnetic Field ◽

Atmosphere Of Venus

AbstractThe upper atmosphere of Venus is not shielded by planetary magnetic field from direct interaction with the solar wind. The interaction of shocked solar wind and the ionosphere results in ionopause. Magnetic barrier, the inner region of dayside magnetosheath with the dominated magnetic pressure deflects the solar wind instead of the ionopause at solar maximum. Therefore, the structure and interaction of venusian ionosphere is very complex. Although the Venus Express (VEX) arrived at Venus in April 2006 provides more knowledge on the Venusian ionosphere and plasma environment, compared to Pioneer Venus Orbiter (PVO) with about 14 years of observations, some important details are still unknown (e.g., long Venusian bow shock variations and effects). In this paper, the bow shock positions of Venus are determined and analyzed from magnetometer (MAG) and ASPERA-4 of the Venus Express mission from May 28, 2006 to August 17, 2010. Results show that the altitude of BS was mainly affected by SZA (solar zenith angle) and Venus bow shocks inbound and outbound are asymmetry.

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Pulsar wind nebulae created by fast-moving pulsars

Journal of Plasma Physics ◽

10.1017/s0022377817000630 ◽

2017 ◽

Vol 83 (5) ◽

Cited By ~ 30

Author(s):

O. Kargaltsev ◽

G. G. Pavlov ◽

N. Klingler ◽

B. Rangelov

Keyword(s):

Hubble Space Telescope ◽

Ambient Medium ◽

Pulsar Wind Nebulae ◽

The Past ◽

Recent Developments ◽

Pulsar Velocity ◽

Bow Shocks ◽

Observational Status ◽

Pulsar Wind ◽

Made In

We review multiwavelength properties of pulsar wind nebulae created by supersonically moving pulsars and the effects of pulsar motion on the pulsar wind nebulae morphologies and the ambient medium. Supersonic pulsar wind nebulae are characterized by bow-shaped shocks around the pulsar and/or cometary tails filled with the shocked pulsar wind. In the past several years significant advances in supersonic pulsar wind nebula studies have been made in deep observations with the Chandra and XMM-Newton X-ray observatories and the Hubble Space Telescope. In particular, these observations have revealed very diverse supersonic pulsar wind nebula morphologies in the pulsar vicinity, different spectral behaviours of long pulsar tails, the presence of puzzling outflows misaligned with the pulsar velocity and far-UV bow shocks. Here we review the current observational status focusing on recent developments and their implications.

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V-waves, bow shocks, and wakes in supercritical hydrostatic flow

Journal of Fluid Mechanics ◽

10.1017/s0022112099007636 ◽

2000 ◽

Vol 406 ◽

pp. 27-53 ◽

Cited By ~ 22

Author(s):

QINGFANG JIANG ◽

RONALD B. SMITH

Keyword(s):

Single Layer ◽

Wave Drag ◽

Bow Shock ◽

Subcritical State ◽

Supercritical Flow ◽

Ambient Flow ◽

Bow Shocks ◽

State Regime ◽

Layer Flow ◽

V Wave

The structure of the bow shock, V-wave, and the related wave drag and wake in supercritical ambient flow are investigated for homogeneous hydrostatic single-layer flow with a free surface over an isolated two-dimensional (i.e. h(x, y)) obstacle. The two control parameters for this physical system are the ratio of obstacle height to fluid depth and the Froude number F = U/√gH. Based on theoretical analysis and numerical modelling, a steady-state regime diagram is constructed for supercritical flow. This study suggests that supercritical flow may have an upstream bow shock with a transition from the supercritical state to the subcritical state near the centreline, and a V-shock in the lee without a state transition. Unlike subcritical flow, neither a flank shock nor a normal lee shock is observed, due to the local supercritical environment. Both the bow shock and V-shock are dissipative and reduce the Bernoulli constant, but the vorticity generation is very weak in comparison with subcritical ambient flow. Thus, in supercritical flow, wakes are weak and eddy shedding is absent.Formulae for V-wave shape and V-wave drag are given using linear theory. Both formulae compare well with numerical model runs for small obstacles.These results can be applied to air flow over mountains, river hydraulics and coastal ocean currents with bottom topographies.

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Fast-moving pulsars as probes of interstellar medium

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa1601 ◽

2020 ◽

Vol 497 (3) ◽

pp. 2605-2615

Author(s):

Maxim V Barkov ◽

Maxim Lyutikov ◽

Dmitry Khangulyan

Keyword(s):

Interstellar Medium ◽

Fast Moving ◽

Supernova Remnant ◽

Characteristic Length ◽

Line Emission ◽

Bow Shock ◽

Spatial Inhomogeneity ◽

X Rays ◽

Forward Shock ◽

Bow Shocks

ABSTRACT Pulsars moving through interstellar medium (ISM) produce bow shocks detected in hydrogen H α line emission. The morphology of the bow shock nebulae allows one to probe the properties of ISM on scales ∼0.01 pc and smaller. We performed 2D relativistic magnetohydrodynamic modelling of the pulsar bow shock and simulated the corresponding H α emission morphology. We find that even a mild spatial inhomogeneity of ISM density, δρ/ρ ∼ 1, leads to significant variations of the shape of the shock seen in H α line emission. We successfully reproduce the morphology of the Guitar Nebula. We infer quasi-periodic density variations in the warm component of ISM with characteristic length of ∼0.1 pc. Structures of this scale might be also responsible for the formation of the fine features seen at the forward shock of Tycho supernova remnant (SNR) in X-rays. Formation of such short periodic density structures in the warm component of ISM is puzzling, and bow-shock nebulae provide unique probes to study this phenomenon.

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Optical Observations of Pulsars

Symposium - International Astronomical Union ◽

10.1017/s0074180900092950 ◽

1981 ◽

Vol 95 ◽

pp. 221-234

Author(s):

F. Graham Smith

Keyword(s):

Ultra Violet ◽

Optical Observations ◽

Crab Pulsar ◽

Radio Pulsars ◽

Optical Identification ◽

Absorption Effect ◽

Time Resolved ◽

Pulse Cycle ◽

Infra Red ◽

Minimum Intensity

Optical identification of radio pulsars has only been achieved for the Crab and Vela Pulsars. The luminosity limits for others could be considerably improved: better astrometry and time-resolved photometry could reach mv = 27. The limits for pulsars with unknown periods, for example in extragalactic nebulae, are usually about mv = 20. The luminosity falls rapidly with increasing period: if it follows a power law the index is minus ten at least.The optical spectrum of the Crab Pulsar falls toward the infra-red and is flat in the ultra-violet. No self-absorption effect is seen in the infra-red. New observations of the minimum intensity and of the polarisation show a highly linearly polarised component continuing through the whole pulse cycle.

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