Investigation of Markarian galaxies with multiple nuclei

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1989

OSTI ID:6231431

Mazzarella, J M

Optical CCD images, long-slit spectroscopic data, coadded IRAS fluxes, and global H I line profiles are analyzed for a sample of 125 Markarian galaxies reported earlier to possess multiple optical nuclei or extreme morphological peculiarities. Twenty-six objects are isolated which display the strongest evidence for ongoing mergers between disk galaxies; the remainder consist of separated interacting systems, single late-type galaxies with multiple giant H II regions, plus a few ambiguous objects. The merger candidates are involved in low velocity encounters. H alpha and far-infrared luminosities indicate star formation rates that are an average of 3 to 10 times higher than in isolated disk galaxies. The presence of 8 Seyfert nuclei and 5 LINERs among 52 merger nuclei indicates a higher incidence of AGNs compared to isolated spirals at a significance level of 99.9 percent, and there is a higher fraction of AGN pairs than would be expected if the merger process did not induce Seyfert-like activity. Evidence for coupling between the ionization levels of the paired nuclei suggests either mixing by gas transfer between the components, or a selection bias towards pairs of galaxies with similar mass and metal abundances. Correlations between nuclear emission-line properties and global FIR properties indicate that the nuclei and giant H II regions are responsible for the bulk of the FIR luminosity. Radio continuum maps and optical images of Markarian 266 reveal the presence of a strong synchrotron source located between the active nuclei. This is interpreted as shock-induced acceleration of cosmic rays during the ongoing merger of two disk galaxies. Large scale shocking of the interstellar medium may also trigger star formation and destroy large dust grains, resulting in warm far-infrared emission which characterizes colliding disk galaxies.

• Research Organization: Michigan Univ., Ann Arbor, MI (USA)
• OSTI ID: 6231431
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
COSMIC RADIO SOURCES
DATA
EXPERIMENTAL DATA
GALAXIES
H1 REGIONS
H2 REGIONS
INFORMATION
INFRARED SPECTRA
INTERSTELLAR SPACE
LUMINOSITY
MARKARIAN GALAXIES
NUCLEI
NUMERICAL DATA
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
SEYFERT GALAXIES
SPACE
SPECTRA
STAR EVOLUTION