A New Catalogue of Galactic SNRs Corrected for Distance from the Galactic Plane

Milne, D. K.

doi:10.1071/ph790083

Cited by 146 publications

(83 citation statements)

References 2 publications

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“…Due to absorption in the Galactic disk, the minimum radio surface brightness for detecting a SNR is 10 −20 W m −2 Hz −1 sr −1 . Using the empirical relation between the surface brightness Σ, and the diameter of the SNR (Milne 1979), and accounting for the ambient gas density as a function of scale height of the Galactic plane (Tomisaka, Habe, & Ikeuchi 1980), KIT86 reduce the criteria to…”

Section: Diffuse Emissionmentioning

confidence: 99%

RXTEMeasurement of the Diffuse X‐Ray Emission from the Galactic Ridge: Implications for the Energetics of the Interstellar Medium

Valinia

Marshall

1998

ApJ

181

202

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The diffuse X-ray emission from the thin disk surrounding the Galactic midplane (the so-called Galactic ridge) was measured with RXTE PCA in order to determine the spatial extent, spectral nature, and origin of the emission. Spatial examination of the diffuse emission in the central 30 • of the plane in Galactic longitude reveals the presence of two components: a thin disk of full width ∼ < 0 • .5 centered roughly on the Galactic mid-plane, and a broad component which can be approximated as a Gaussian distribution with FWHM of about 4 • . Assuming an average distance of 16 kpc to the edge of the galaxy, a scale height of about 70 pc and 500 pc is derived for the thin and broad disk components, respectively. Spectral examination of the emission clearly reveals the presence of a hard power law tail above 10 keV and an emission line from He-like iron, indicating both thermal and possibly non-thermal origins for the diffuse emission. The averaged spectrum from the ridge in the 3−35 keV band can be modelled with a RaymondSmith plasma component of temperature ∼ 2−3 keV and a power law component of photon index ∼ 1.8. Based on this finding, we argue that the temperature of the hot phase of the Interstellar Medium (ISM) is less than the previously reported values of 5 − 15 keV.Motivated by the similarities between the characteristics of the thermal component of the Galactic ridge emission in our model and the thermal emission from supernova remnants (SNRs), we discuss the origin of the thermal emission in terms of a population of SNRs residing in the Galactic disk. We find that a 1 NAS/NRC Research Associate; valinia@milkyway.gsfc.nasa.gov 2 marshall@milkyway.gsfc.nasa.gov -2 -SN explosion rate of less than 5 per century is adequate to power the thermal emission from the ridge. The origin of the emission in the hard X-ray band modelled by a power law remains uncertain. Possible contributions from non-thermal bremsstrahlung of cosmic ray electrons and protons, inverse Compton scattering of energetic electrons from ambient microwave, infrared, and optical photons, non-thermal emission from SNRs, and emission from discrete X-ray sources are discussed. We speculate that bremsstrahlung of accelerated electrons and protons in SNR sites can play a significant role in producing the hard tail of the spectrum. Moreover, their collisional losses can play a major role in the ionization of the ISM.

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Section: Diffuse Emissionmentioning

confidence: 99%

RXTEMeasurement of the Diffuse X‐Ray Emission from the Galactic Ridge: Implications for the Energetics of the Interstellar Medium

Valinia

Marshall

1998

ApJ

181

202

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“…Current estimates of the distance to 3C 400.2 based on the Σ -D relationship, range from 3.8 to 6.3 kpc (Clark & Caswell 1976;Caswell & Lerche 1979;Milne 1979;Dubner et al 1994); however this method is known to have large intrinsic dispersion. Rosado (1983) derived a distance of 6.7 kpc from the kinematics of the optical filaments, but her estimate is highly uncertain because it is based on interferograms obtained in a small portion of the SNR.…”

Section: The Distance To 3c 4002mentioning

confidence: 99%

The structure of atomic gas around the supernova remnant 3C 400.2

Giacani¹,

Dubner²,

Cappa

et al. 1998

Astron. Astrophys. Suppl. Ser.

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Abstract. The interaction of the SNR 3C 400.2 with the interstellar medium is investigated on the basis of the HI observations using the Synthesis Radio Telescope at the Dominion Radio Astrophysical Observatory (DRAO). These new data show the existence of a dense atomic cloud associated with 3C 400.2 in the velocity range +14 to +42 km s −1 , and high velocity clouds probably accelerated by the supernova blast wave at v = −49.5 km s −1 and +69 km s −1 . We propose that the complex remnant 3C 400.2 is the result of a supernova explosion in a region of the interstellar medium containing a density discontinuity. A breakout phenomenon may explain the observed morphology in the different spectral regimes.

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“…Various authors (e.g., Clark & Caswell 1976;Milne 1979;Caswell & Lerche 1979;Case & Bhattacharya 1998;Urošević et al 2005) have investigated this correlation. Originally applied as a tool for estimating SNR distances, it has been found to be unreliable for this purpose.…”

Section: Introductionmentioning

confidence: 99%

A statistical approach to radio emission from shell-type SNRs

Bandiera¹,

Petruk

2009

A&A

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Context. Shell-type supernova remnants (SNRs) exhibit correlations between radio surface brightness, SNR diameter, and ambient medium density, that between the first two quantities being the well known Σ-D relation. Aims. We investigate these correlations, to extract useful information about the typical evolutionary stage of radio SNRs, as well as to obtain insight into the origin of the relativistic electrons and magnetic fields responsible for the synchrotron emission observed in radio.Methods. We propose a scenario, according to which the observed correlations are the combined effect of SNRs evolving in a wide range of ambient conditions, rather than the evolutionary track of a "typical" SNR. We then develop a parametric approach to interpret the statistical data, and apply it to the data sample previously published by Berkhuijsen, as well as to a sample of SNRs in the galaxy M 33. Results. We find that SNRs cease to emit effectively in radio at a stage near the end of their Sedov evolution, and that models of synchrotron emission with constant efficiencies in particle acceleration and magnetic field amplification do not provide a close match to the data. We discuss the problem of the cumulative distribution in size, showing that the slope of this distribution does not relate to the expansion law of SNRs, as usually assumed, but only to the ambient density distribution. This solves a long-standing paradox: the almost linear cumulative distribution of SNRs led several authors to conclude that these SNRs are still in free expansion, which also implies very low ambient densities. Within this framework, we discuss the case of the starburst galaxy M 82. Conclusions. Statistical properties of SNR samples may be used to shed light on both the physics of electron acceleration and the evolution of SNRs. More precise results could be obtained by combining data of several surveys of SNRs in nearby galaxies.

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A New Catalogue of Galactic SNRs Corrected for Distance from the Galactic Plane

Cited by 146 publications

References 2 publications

RXTEMeasurement of the Diffuse X‐Ray Emission from the Galactic Ridge: Implications for the Energetics of the Interstellar Medium

RXTEMeasurement of the Diffuse X‐Ray Emission from the Galactic Ridge: Implications for the Energetics of the Interstellar Medium

The structure of atomic gas around the supernova remnant 3C 400.2

A statistical approach to radio emission from shell-type SNRs

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