Evidence for an Explosion in the Center of the Galaxy M82.

Abstract

view Abstract Citations (3) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Evidence for an Explosion in the Center of the Galaxy M82. Lynds, C. R. ; Sandage, A. R. Abstract New observations in optical frequencies of the peculiar optical and radio galaxy M82 reveal a massive system of filaments which extends along the minor axis to a height of 3000 pc above and below the fundamental plane. Emission lines typical of low-excitation gaseous nebulae are present. The filaments on both sides of the plane appear to be expanding from the center along the minor axis with velocities ranging up to about 1000 km/sec. The data suggest that an expulsion of matter took place from the central regions of M82 about 1.5 X 106 yr ago. The Ha emission flux from the filaments is estimated to be 1.7 x 10-11 erg cm-2 sec-1 at the earth's surface, which requires a total emitted power of 2 X 1040 erg sec-1 in Ha if the distance modulus of M82 is m-M=27.5. The ion density in the filaments, estimated from the volume emissivity, is 10 protons cm-3, which then requires thst the visible mass of the expanding material is 5.6X106 Mo as an upper limit. An upper limit to the kinetic energy of the visible filaments is 2.4 X 10~ ergs. The filaments form fragments of loops and appear to outline lines of magnetic force. Parts of the filaments appear to radiate weakly in the continuum as well as in the emission lines, and this suggests that optical synchrotron radiation may be present. Polarization measurements of part of the filamentary structure by Elvius and Hall seem to be consistent with this possibility. The radio flux data are combined with an estimate of the optical synchrotron flux, and a theoretical power spectrum is computed. The rate of synchrotron radiation is 2 X 1042 erg sec-1 which amounts to 9 X 10~~ ergs over the lifetime of 1.5 X 106 yr if the power level has been constant over this time interval. Calculation shows that the source of excitation for the observed low-energy recombination spectrum may be the optical synchrotron radiation field which extends to frequencies above the Lyman limit. Publication: The Astronomical Journal Pub Date: September 1963 DOI: 10.1086/109098 Bibcode: 1963AJ.....68R.284L full text sources ADS |