Diffusive shock acceleration in the lobes of the Serpens triple radio source

Crusius-Wätzel, A. R.

doi:10.1086/185824

Cited by 21 publications

(15 citation statements)

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“…He found that amplification to a few µG with this mechanism is very rare. Magnetic field strengths of a few µG have previously been inferred from studies of the excess rotation measure (RM) (Kim et al 1990;Crusius-Watzel et al 1990;Kim, Kronberg, & Tribble 1991) in galaxy clusters. Though these high magnetic fields challenge the hypothesis of wake amplification, they are more model dependent as they are sensitive to local density inhomogeneities or an asymmetric gas distribution.…”

Section: Discussionmentioning

confidence: 99%

RXTEandASCAConstraints on Nonthermal Emission from the A2256 Galaxy Cluster

Henriksen

1999

ApJ

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An 8.3 hour observation of the Abell 2256 galaxy cluster using the Rossi X-ray Timing Explorer (RXTE) proportional counter array (PCA) produced a high quality spectrum in the 2 -30 keV range. Joint fitting with the 0.7 -11 keV spectrum obtained with the Advanced Satellite for Astrophysics and Cosmology (ASCA) Gas Imaging spectrometer (GIS) gives an upperlimit of ∼2.3×10 −7 photons cm −2 sec −1 keV −1 for non-thermal emission at 30 keV. This yields a lower limit to the mean magnetic field of 0.36µG and an upperlimit of 1.8×10 −13 ergs cm −3 for the cosmic-ray electron energy density. The resulting lower limit to the central magnetic field is ∼1 -3 µG. While a magnetic field of ∼0.1 -0.2 µG can be created by galaxy wakes, a magnetic field of several µG is usually associated with a cooling flow or, as in the case of the Coma cluster, a subcluster merger. However, for A2256, the evidence for a merger is weak and the main cluster shows no evidence of a cooling flow. Thus, there is presently no satisfactory hypothesis for the origin of an average cluster magnetic field as high as > 0.36 µG in the A2256 cluster.

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Section: Discussionmentioning

confidence: 99%

RXTEandASCAConstraints on Nonthermal Emission from the A2256 Galaxy Cluster

Henriksen

1999

ApJ

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“…However, if the accuracy in the determination of φ is of the order of π the inferred determination of the angular coefficient of the linear regression (3.8) is ambiguous. The suggestion to study the mean-squared fluctuation of the RM was proposed [33,34]. More recently, using this statistical approach particularly appropriate in the case of magnetic fields in clusters (where both the magnetic field intensity and the electron density change over the integration path), Newmann, Newmann and Rephaeli [35] quantified the possible (statistical) uncertainty in the determination of cluster magnetic fields (this point will also be discussed later).…”

Section: Faraday Rotation Measurementsmentioning

confidence: 99%

The Magnetized Universe

Giovannini

2004

Int. J. Mod. Phys. D

392

518

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Cosmology, high-energy physics and astrophysics are converging on the study of large-scale magnetic fields. While the experimental evidence for the existence of large-scale magnetization in galaxies, clusters and superclusters is rather compelling, the origin of the phenomenon remains puzzling especially in light of the most recent observations. The purpose of the present review is to describe the physical motivations and some of the open theoretical problems related to the existence of large-scale magnetic fields.

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“…We suggest that the radio emission from the lobes arises in shocks resulting from the interaction of a collimated stellar wind with the surrounding medium. In shock waves moving through a magnetized medium, a small fraction of the electrons are accelerated to relativistic velocities, giving rise to nonthermal synchrotron emission, while most of the electrons produce thermal freefree emission (Crusius-Wätzel 1990;Henriksen, Ptuskin, & Mirabel 1991). The production of relativistic electrons is understood in terms of a diffusive shock-wave acceleration mechanism in which the electrons are accelerated by traversing the shock many times due to scattering off magnetohydrodynamic irregularities (cf.…”

Section: The Nature Of the Triple Radio Sourcementioning

confidence: 99%

A Triple Radio Continuum Source Associated with IRAS 16547–4247: A Collimated Stellar Wind Emanating from a Massive Protostar

Garay

Brooks

Mardones

et al. 2003

ApJ

135

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We report the discovery, made using the Australia Telescope Compact Array, of a triple radio source toward IRAS 16547À4247, a luminous infrared source with a bolometric luminosity of 6:2 Â 10 4 L . The radio source shows an almost linear structure consisting of a compact central object and two outer lobes separated by about 20 00 , located symmetrically to the central source. The radio emission from the lobes has spectral indices of À0.61 and À0.33, characteristic of nonthermal emission. The emission from the central object has a spectral index of 0.49, consistent with free-free emission from a thermal jet. Also reported are 1.2 mm continuum and molecular line observations made with the Swedish ESO Submillimeter Telescope. The 1.2 mm observations show that the dust emission arises from a region of 33 00 Â 25 00 (FWHM) with a total flux of 16.4 Jy, implying a mass of 1:3 Â 10 3 M . The line observations indicate that IRAS 16547À4247 is associated with a molecular core with a FWHM deconvolved angular size of 27 00 (diameter of 0.38 pc at the distance of 2.9 kpc), a molecular hydrogen density of 5:2 Â 10 5 cm À3 , and a mass of 9:0 Â 10 2 M . We propose that this dense massive core hosts a high-mass star in an early stage of evolution in which it is undergoing the ejection of a collimated stellar wind. The radio emission from the lobes arises in shocks resulting from the interaction of this collimated wind with the surrounding medium. Our observations indicate that the jets found in the formation of low-mass stars are also produced in high-mass stars, with IRAS 16547À4247 being the most luminous young stellar object presently known to host a jet.

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Diffusive shock acceleration in the lobes of the Serpens triple radio source

Cited by 21 publications

References 0 publications

RXTEandASCAConstraints on Nonthermal Emission from the A2256 Galaxy Cluster

RXTEandASCAConstraints on Nonthermal Emission from the A2256 Galaxy Cluster

The Magnetized Universe

A Triple Radio Continuum Source Associated with IRAS 16547–4247: A Collimated Stellar Wind Emanating from a Massive Protostar

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