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|Circumnuclear star-forming activities along the Hubble sequence|
In order to study circumnuclear star-forming activity along the Hubblesequence, we cross-correlated the Sloan Digital Sky Survey Data Release2 (SDSS DR2) with the Third Reference Catalog of Bright Galaxies (RC3)to derive a large sample of 1015 galaxies with both morphological andspectral information. Among these, 385 sources are classified asstar-forming galaxies, and the SDSS fibre covered the circumnuclearregions (0.2-2.0 kpc). By using the spectral synthesis method to removethe contribution from the underlying old stellar population, we measuredthe emission lines fluxes accurately, which are then used to estimatethe star-formation rates(SFRs). Our main findings are: (1) early-typespirals show much higher Hα luminosities, and hence higher SFRs,and also suffer more extinctions than late-type ones. The equivalentwidths (EWs) of Hα emission lines show a similar trend; however,the very late types (Sdm ~ Irr) do have large fractions of high EWs; (2)we confirm that D_n(4000) shows a strong correlation with the strengthsof metallic absorption lines (such as CN band, G band, and Mg Ib). Boththese lines and the Balmer absorption lines show interesting variationsbetween Sbc and Sd type galaxies; (3) the bar structure tightly relatesto the enhanced star formation activity, an effect that is even moresignificant in the early-type spirals. But we should note that the barstructure is not a necessary or sufficient condition for galaxies toharbor circumnuclear star formations.
|A multifrequency radio continuum and IRAS faint source survey of markarian galaxies|
Results are presented from a multifrequency radio continumm survey ofMarkarian galaxies (MRKs) and are supplemented by IRAS infrared datafrom the Faint Source Survey. Radio data are presented for 899 MRKsobserved at nu = 4.755 GHz with the National Radio Astronomy Observatory(NRAO)-Green Bank 300 foot (91 m) telescope, including nearly 88% ofthose objects in Markarian lists VI-XIV. In addition, 1.415 GHzmeasurements of 258 MRKs, over 30% of the MRKs accessible from theNational Aeronomy and Ionosphere Center (NAIC)-Arecibo, are reported.Radio continuum observations of smaller numbers of MRKs were made at10.63 GHz and at 23.1 GHz and are also presented. Infrared data from theIRAS Faint Source Survey (Ver. 2) are presented for 944 MRKs, withreasonably secure identifications extracted from the NASA/IPACExtragalactic Database. MRKs exhibit the same canonical infraredcharacteristics as those reported for various other galaxy samples, thatis well-known enhancement of the 25 micrometer/60 micrometer color ratioamong Seyfert MRKs, and a clear tendency for MRKs with warmer 60micrometer/100 micrometer colors to also possess cooler 12 micrometer/25micrometer colors. In addition, non-Seyfert are found to obey thewell-documented infrared/radio luminosity correlation, with the tightestcorrelation seen for starburst MRKs.
|Pairing properties of Markarian starburst Galaxies|
The environmental parameters of 516 non-Seyfert Markarian galaxies werestudied in a redshift-bounded sample, supplemented by new spectra andredshift measures for possible companions, in order to evaluate theiroccurrence in galaxy pairs, defined through quantitative criteria. Itwas found that one-third of these galaxies occur in pairs (while only 6to 10 percent of optically-selected galaxies are known to be paired). Acomparison of various optical and IR properties of paired and nonpairedMarkarian galaxies showed no differences in the shape of the optical,far-IR, or H-alpha luminosity functions. It was found, however, that theMarkarian component is brighter than the other galaxy in each pair by0.66 magnitude in the mean at B.
|A catalog of Markarian galaxies|
A catalog of Markarian galaxies is presented which tabulates redshifts,spectral and morphological classifications, magnitudes, infrared andradio flux densities, and over 600 references to available datapublished before January 1, 1986. Redshifts are now available for 1228objects with strong ultraviolet continua, and follow-up spectroscopicand photometric observations of Markarian galaxies have providedclassifications of 115 Seyfert 1, 43 Seyfert 2, and 137 starburst and HII-type galaxies. After a description of the Markarian survey and thecurrent catalog, a summary of the general results obtained from the datais presented. A preliminary study of the infrared properties ofMarkarian galaxies as measured by IRAS reveals a number of interestingresults, including the existence of a sample of elliptical andlenticular galaxies with appreciable infrared emission.
|Accurate Optical Positions for Markarian Galaxies 1096-1302|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1981AJ.....86..816K&db_key=AST
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