The Balmer-dominated northeast limb of the Cygnus loop supernova remnant

Hester, J. J.; Raymond, J. C.; Blair, William P.

doi:10.1086/173598

Cited by 159 publications

(195 citation statements)

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“…This points to the widespread presence of shocks in excess of 160 km s À1 , only some of which have recombined to the point of producing bright optical line emission. It may also point to the presence of considerable nonradiative shock emission, for which bright O vi and other UV line emission is seen even though their optical output is limited to faint Balmer line emission (Long et al 1992;Hester et al 1994;Sankrit et al 2000). Indeed, the relatively faint, red filament arcing northward from aperture E2L in Figure 1 is likely a nonradiative shock from elsewhere along the line of sight seen in projection.…”

Section: Discussionmentioning

confidence: 97%

“…It is relatively recently, for instance, that we have come to recognize the Cygnus Loop as the remnant of a core collapse supernova, and that the explosion probably occurred in a cavity evacuated by the progenitor star (Charles, Kahn, & McKee 1985;Hester, Raymond, & Blair 1994;Levenson et al 1997Levenson et al , 1998Bohigas, Sauvageot, & Decourchelle 1999). It is the relatively recent encounter between the SNR blast wave and the cavity wall in its various manifestations (atomic and molecular material distributed in clouds of varying size and density) that is responsible for the dazzling array of structures and phenomena available for study.…”

Section: Introductionmentioning

confidence: 99%

“…Early studies concentrated on bright optical filaments and characterized the phenomenology of the far-UV spectral region, comparing with steady-flow shock models (Raymond 1979;Shull & McKee 1979) to infer shock conditions (Raymond et al 1980(Raymond et al , 1981Benvenuti, Dopita, & D'Odorico 1980). Subsequent investigations pushed to fainter filaments (Raymond et al 1983;Long et al 1992) and to multiwavelength investigations of small regions (Raymond et al 1988;Hester, Raymond, & Blair 1994;Sankrit et al 2000). Such studies continue on to the present, with the recent work of Danforth, Blair, & Raymond (2001) who have performed a detailed study of the so-called '' XA '' region in the Cygnus Loop.…”

Section: Introductionmentioning

confidence: 99%

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Far Ultraviolet Spectroscopic Explorer and Hopkins Ultraviolet Telescope Observations of Radiative Shocks in the Cygnus Loop

Blair

Sankrit

Tulin

2002

ASTROPHYS J SUPPL S

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We report a combination of high and low spectral resolution far-ultraviolet spectral data for several groupings of bright radiative shock filaments in the Cygnus Loop supernova remnant. The high-resolution spectra were obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE) satellite and cover the 905-1187 Å spectral region at 0.1-0.3 Å resolution, depending on observing aperture. The low-resolution data were obtained with the Hopkins Ultraviolet Telescope (HUT) and cover the 850-1850 Å spectral region at $3 Å resolution. These data sets complement each other, with the HUT data providing the broader context of a wider range of emission lines and the FUSE data resolving line profiles from nearby airglow emissions and allowing detailed line profiles to be studied. Relative line intensities and line profiles change on a wide variety of spatial scales. O vi 1032, 1038 emission is much more generally distributed than the optical filaments. The FUSE data provide direct insight into the effects and variability of self-absorption in the strong resonance lines of O vi and C iii 977. Variability of the central reversals in O vi with position indicate a patchy O vi distribution, with self-absorption occurring locally within the remnant. Self-absorption in C iii could be due to the interstellar medium, the local regions of the remnant, or a combination. We also find evidence for overlying molecular hydrogen absorption effects on some lines and suggest an interstellar (foreground) origin. It is likely that these effects have had significant impacts on many previous investigations that based their results on the interpretation of low-resolution spectral data where these effects could not be seen.

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Section: Discussionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Far Ultraviolet Spectroscopic Explorer and Hopkins Ultraviolet Telescope Observations of Radiative Shocks in the Cygnus Loop

Blair

Sankrit

Tulin

2002

ASTROPHYS J SUPPL S

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“…The first clue that Balmer emission could provide evidence for the presence of accelerated particles was put forward as a possible way to explain the anomalous width of narrow Balmer lines reported for the first time by [6] and [7]: FWHM ranging from 30 to 50 km s −1 was detected for four SNRs in the LMC and for the Cygnus Loop, implying a pre-shock temperature around 25,000-50,000 K. Values in the same range have been reported afterwards for other SNRs (see, e.g. [8]).…”

Section: Introductionmentioning

confidence: 99%

Using optical lines to study particle acceleration at supernova remnants

Morlino

2014

Nuclear Physics B - Proceedings Supplements

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The shocks of several young supernova remnants (SNR) are often associated with very thin optical filaments dominated by Balmer emission resulting from charge-exchange and collisional excitation between neutral Hydrogen from the interstellar medium and shocked protons and electrons. Optical lines are a direct probe of the conditions at the shock, in particular the width of the narrow and broad components reflect the temperature upstream and downstream of the shock, respectively. When the shock accelerate efficiently non-thermal particles, the shock structure changes producing anomalous Balmer lines and it is possible to use their line shape and their spatial profile to check the efficiency of SNR shocks in accelerating cosmic rays. Here we illustrate the kinetic theory of shock acceleration in presence of neutrals with some applications to young SNRs. We show that in three cases (RCW 86, SNR 0509-67.5 and Tycho) anomalous Balmer lines can be explained assuming that a fraction of ∼ 10% of the total shock kinetic energy is converted into not thermal particles, while in one single case, the northwestern part of SN 1006, there is no evidence of efficient acceleration.

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“…Smith et al (1994) measured narrow component widths of 25-58 km/s in four LMC Balmer-dominated remnants, and Hester et al (1994) found a 28-35 km/s width in a Cygnus Loop shock. These line widths correspond to temperatures of about (2-7)× 10 4 K, and in static equilibrium, hydrogen is fully ionized at those temperatures.…”

Section: Shock Precursorsmentioning

confidence: 99%

Collisionless Shocks in Partly Ionized Plasma with Cosmic Rays: Microphysics of Non-thermal Components

Bykov

Malkov

Raymond

et al. 2013

Microphysics of Cosmic Plasmas

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In this review we discuss some observational aspects and theoretical models of astrophysical collisionless shocks in partly ionized plasma with the presence of nonthermal components. A specific feature of fast strong collisionless shocks is their ability to accelerate energetic particles that can modify the shock upstream flow and form the shock precursors. We discuss the effects of energetic particle acceleration and associated magnetic field amplification and decay in the extended shock precursors on the line and continuum multi-wavelength emission spectra of the shocks. Both Balmer-type and radiative astrophysical shocks are discussed in connection to supernova remnants interacting with partially neutral clouds. Quantitative models described in the review predict a number of observable line-like emission features that can be used to reveal the physical state of the matter in the shock precursors and the character of nonthermal processes in the shocks. Implications of recent progress of gamma-ray observations of supernova remnants in molecular clouds are highlighted.

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The Balmer-dominated northeast limb of the Cygnus loop supernova remnant

Cited by 159 publications

References 0 publications

Far Ultraviolet Spectroscopic Explorer and Hopkins Ultraviolet Telescope Observations of Radiative Shocks in the Cygnus Loop

Far Ultraviolet Spectroscopic Explorer and Hopkins Ultraviolet Telescope Observations of Radiative Shocks in the Cygnus Loop

Using optical lines to study particle acceleration at supernova remnants

Collisionless Shocks in Partly Ionized Plasma with Cosmic Rays: Microphysics of Non-thermal Components

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