[35.02] molecular gas in the taffy galaxies (UGC 12914/15)
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molecular gas taffy galaxies↗
Engineering topics
Seaquist, E. R.
Publications and source records attributed to Seaquist, E. R..
A nonthermal radio halo surrounding M82
Radio maps at several frequencies are presented which reveal an extended halo of nonthermal emission surrounding the starburst galaxy M82. The origin of this halo is probably synchrotron radiation from relativistic electrons originally produced in SNR, swept out of the disk by the extensive wind associated with the galaxy. The halo appears to be asymmetrical, with an enhancement occurring about 1 arcmin to the south, and on a larger scale there is excess emission to the north. Possible causes of this effect are addressed. The spectral index measured using data at 6, 20, 49, and 90 cm is about -0.4 + or - 0.1 in the nucleus, steepening to about -1.0 in the halo. A simple model is invoked which involves outward convection of relativistic particles with electron energy losses by inverse Compton scattering against IR photons and adiabatic expansion.
Seaquist, E. R.↗
A synchrotron halo around M82
We report the discovery of a nonthermal radio halo surrounding the prototypical starburst galaxy M82. Some of the features of the halo are discussed along with its relationship to the outflow and supernova activity in the nucleus.
Seaquist, E. R.↗
Synchrotron emission as a tracer of the outflow in M82
The discovery of radio synchrotron emission from the outflow in M82 is reported. It is found that the outflow in M82 is visible in synchrotron radiation. IC losses are evident in the steepening of the radio spectrum, though this process is not a major contributor to the observed halo X-ray emission. Particle acceleration and/or diffusion in the wind may be important. Outflow speeds of 1000-3000 km/s are inferred from the spectral index profiles, which significantly exceeds the optically determined values. The fraction of the wind energy in the form of relativistic particles is consistent with a supernova origin. A termination shock produced by the intergalactic medium may be shaping the observed halo of M82.
Seaquist, E. R.↗
The unusual radio outburst of Nova Vulpeculae 1984 No. 2
Multifrequency radio monitoring of Nova Vulpeculae 1984 No. 2 has revealed a unique radio light curve, exhibiting a strong outburst which precedes the appearance of normal radio emission from the principal ejecta of the nova by at least 100 days. The early emission is extremely optically-thick and has brightness temperature in excess of 100,000 K. A model is discussed in which the radiation is produced by a strong shock propagating outward through the principal ejecta of the nova, as a result of an interaction with a later, high velocity wind from the central source. It is shown that the general features of the radio light curve can be explained by the presence of a central wind with a mass loss rate of about 0.00001 solar masses/yr, lasting for a period of 200 to 300 days after the optical outburst. The first radio map of nova ejecta shortly after outburst is presented. Comparison of the angular expansion rate to the ejection velocity implies a distance of 3.6 kpc, and preliminary analysis of the main outburst emission indicates a mass and kinetic energy of the ejecta respectively of about 0.0008 solar masses and 8 x 10 to the 45th erg.
Taylor, A. R.↗