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Starburst or Seyfert? Adding a Radio and Far-Infrared Perspective to the Investigation of Activity in Composite Galaxies
It was once common to regard Seyfert and starburst galaxies ascompletely different types of object, but there is growing recognitionthat these classifications refer to the extremes of a continuousspectrum of galaxy types. In a previous study we investigated a sampleof galaxies with ambiguous optical emission-line ratios and concludedfrom near-infrared spectroscopic observations that the sample consistedof composite galaxies, containing both a starburst and an activegalactic nucleus (AGN). We now extend our study using radio synthesisand long-baseline interferometer observations made with the AustraliaTelescope, together with far-infrared IRAS observations, to discuss therelative contribution of starburst and AGN components to the overallluminosity of the composite galaxies. We find that only a small fractionof the radio emission (<10%) can be attributed to an AGN and that themajority of the far-infrared emission (>90%) is probably due to thestarburst component. We also show that an AGN contribution to theoptical emission of as little as 10% is sufficient to account for theambiguous line-ratio diagnostics.
| Numerous Old Starburst Galaxies in the Local Universe
Old starburst galaxies are deficient in O stars and hence do not exhibitstrong line emission in the optical regime. However, there remain many Bstars, which are expected to heat dust grains and generate strongcontinuum emission in the far-infrared. The IRAS data for astatistically complete sample of nearby galaxies reveal for the firsttime that such objects are as numerous as 30%-40% of the local galaxypopulation.
| Arcsecond Positions of UGC Galaxies
We present accurate B1950 and J2000 positions for all confirmed galaxiesin the Uppsala General Catalog (UGC). The positions were measuredvisually from Digitized Sky Survey images with rms uncertaintiesσ<=[(1.2")2+(θ/100)2]1/2,where θ is the major-axis diameter. We compared each galaxymeasured with the original UGC description to ensure high reliability.The full position list is available in the electronic version only.
| The Disks of Galaxies with Seyfert and Starburst Nuclei. II. Near-Infrared Structural Properties
We have derived the near-infrared structural components of a sample ofSeyfert and starburst (SBN) host galaxies by fitting near-infraredimages with a new two-dimensional decomposition algorithm. An analysisof the fitted parameters shows that Seyfert 1 and SBN bulges resemblenormal early-type bulges in structure and color, with (J-K)^c_b about0.1 mag redder than disk (J-K)^c_d. Seyfert 2 bulges, on the other hand,are bluer than normal, with (J-K)^c_b ~ (J-K)^c_d. Seyfert disks(especially type 1), but not those of SBNs, are abnormally bright (insurface brightness), significantly more so than even the brightestnormal disks. Seyfert disks are also compact, but similar to those innormal early-type spirals. For a given mass, Seyfert and particularlySBN galaxies are abnormally rich in neutral hydrogen, and there isstrong, albeit indirect, evidence for lower mass-to-light (M/L) ratiosin Seyfert and SBN disks, but normal M/L ratios in their bulges. InSeyfert and SBN galaxies, H I mass fractions and M/L ratios areanticorrelated, and we attribute the high gas mass fractions and low M/Lratios in SBNs and several Seyfert galaxies to ongoing star formation.Such abundant gas in Seyfert galaxies would be expected to inhibit barformation, which may explain why active galaxies are not always barred.
| The Supernova Rate in Starburst Galaxies
We conducted an optical CCD search for supernovae in a sample of 142bright [m(B) <= 16 mag], nearby (z<=0.03) starburst galaxies overthe period 1988 December to 1991 June, to a limiting R-band magnitude of18. Five supernovae were found, in all cases outside the host galaxy'snucleus. We determine supernova rates (in supernova units or SNU) in theextranuclear regions to be 0.7 h^2 SNU for Type Ia, 0.7 h^2 SNU for TypeIb/c, and ~0.6 h^2 SNU for Type II, with large uncertainties but upperlimits of 2.2 h^2, 2.5 h^2, and 1.7 h^2 SNU, respectively. These ratesare similar to those measured in ``normal'' galaxies. We found noevidence for a supernova-induced brightening in any galactic nucleusand, with a few reasonable assumptions, can place upper limits of 9 h^2,12 h^2, and 7 h^2 SNU on the rates of unobscured supernovae Types Ia,Ib/c, and II, respectively, inside the nuclei.
| The Disks of Galaxies with Seyfert and Starburst Nuclei. I. Near-Infrared Colors and Color Gradients
We present near-infrared (NIR) broadband and color images of 26 galaxiesthat host Seyfert 1, Seyfert 2, or starburst nuclei (SBNs). The study isfocused on properties of the host galaxies rather than their nuclei, andto this end, careful attention is paid to photometric accuracy and toreliable measurements of the low surface brightness outer disk.Inspection of the elliptically averaged radial brightness and colorprofiles reveals that (1) the NIR mean colors of the inner and outerdisks of Seyfert and starburst galaxies are consistent with those of anormal late-type stellar population and do not differ significantly withactivity class; (2) the color gradients in the outer disks are similarboth in sign and in magnitude to those observed in normal spirals; (3)red "ridges" in the inner parts of the J - H profile are evident in themajority of SBNs, but only in a few type 1 Seyferts and in no type 2's;(4) circumnuclear blue "dips" in the J - H profile are seen only in type2 Seyferts. We then construct color images and find ridges, rings, andfilaments, not evident in the broadband images, in the inner disks ofSBNs and in NGC 7469, a Seyfert 1. The application of a simple model tothese features yields evidence of both dust extinction and excess 2 mu memission. Color-color diagrams of individual pixels confirm theseresults and also show that the stellar mix in most of the Seyfert 2'scomprises a conspicuous contribution from an intermediate-age [(3--5) x108 yr] population. It appears that ongoing star formation in the innerdisks of SBNs is signaled by the presence of dust (and gas); the absenceof such features in both Seyfert types implies that star formationepisodes are either absent or very old. However, while the blue colorsof Seyfert 2's suggest that a burst of star formation did, in fact,occur not more than 109 yr ago, the normal colors of Seyfert 1's implythat any star-forming episodes must be significantly older.
| An image database. II. Catalogue between δ=-30deg and δ=70deg.
A preliminary list of 68.040 galaxies was built from extraction of35.841 digitized images of the Palomar Sky Survey (Paper I). For eachgalaxy, the basic parameters are obtained: coordinates, diameter, axisratio, total magnitude, position angle. On this preliminary list, weapply severe selection rules to get a catalog of 28.000 galaxies, wellidentified and well documented. For each parameter, a comparison is madewith standard measurements. The accuracy of the raw photometricparameters is quite good despite of the simplicity of the method.Without any local correction, the standard error on the total magnitudeis about 0.5 magnitude up to a total magnitude of B_T_=17. Significantsecondary effects are detected concerning the magnitudes: distance toplate center effect and air-mass effect.
| 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.
| Gas content of infrared luminous markarian galaxies
The atomic and molecular hydrogen gas properties of a complete sample ofMarkarian galaxies with flux density at 60 µm higher than 1.95 Jyare presented. We present the improved far-infrared luminosity functionof Markarian galaxies; and its comparison with other samples. We findthat 40% of the bright IRAS galaxies of far-infrared luminosity higherthan 1010.5 L are Markarian galaxies. There is an absence of correlationbetween HI content of Markarian galaxies and current star formationactivity, implying that star formation in these systems has complexstructure and it is not a simple function of the HI content. On thecontrary, the H2 content of Markarian galaxies is well correlated withstar formation activity. It is argued that tight correlation between HIand H2 contents is a consequence of transformation of atomic hydrogeninto molecular.
| The extended 12 micron galaxy sample
We have selected an all-sky (absolute value of b greater than or equalto 25 deg) 12 micron flux-limited sample of 893 galaxies from the IRASFaint Source Catalog, Version 2 (FSC-2). We have obtained accurate totalfluxes in the IRAS wavebands by using the ADDSCAN procedure for allobjects with FSC-2 12 micron fluxes greater than 0.15 Jy and increasingflux densities from 12 to 60 microns, and defined the sample by imposinga survey limit of 0.22 Jy on the total 12 micron flux. Its completenessis verified, by means of the classical log N - log S andV/Vmax tests, down to 0.30 Jy, below which we have measuredthe incompleteness down to the survey limit, using the log N - log Splot, for our statistical analysis. We have obtained redshifts (mostlyfrom catalogs) for virtually all (98.4%) the galaxies in the sample.Using existing catalogs of active galaxies, we defined a subsample of118 objects consisting of 53 Seyfert 1s and quasars, 63 Seyfert 2s, andtwo blazars (approximately 13% of the full sample), which is the largestunbiased sample of Seyfert galaxies ever assembled. Since the 12 micronflux has been shown to be about one-fifth of the bolometric flux forSeyfert galaxies and quasars, the subsample of Seyferts (includingquasars and blazars) is complete not only to 0.30 Jy at 12 microns butalso with respect to a bolometric flux limit of approximately 2.0 x10-10 ergs/s/sq cm. The average value of V/Vmaxfor the full sample, corrected for incompleteness at low fluxes, is 0.51+/- 0.04, expected for a complete sample of uniformly distributedgalaxies, while the value for the Seyfert galaxy subsample is 0.46 +/-0.10. We have derived 12 microns and far-infrared luminosity functionsfor the AGNs, as well as for the entire sample. We extracted from oursample a complete subsample of 235 galaxies flux-limited (8.3 Jy) at 60microns. The 60 micron luminosity function computed for this subsampleis in satisfactory agreement with the ones derived from the brightgalaxy sample (BGS) and the deep high-galactic latitude sample, bothselected at 60 microns.
| Segregation of gas and stars in shell galaxies
Using a code which is capable of evolving composite systems ofcollisionless matter and gas, we explore mergers like those thoughtresponsible for the shells seen around many elliptical galaxies. If asmall companion containing both gas and stars is accreted by a moremassive primary, the stellar and gaseous debris are rapidly segregated:while the stars are free to oscillate back and forth in the primary'spotential, thereby forming shells, the oppositely directed flows nearthe center of the primary effectively dissipate the orbital kineticenergy of the gas. Consequently, the gas settles into compact disks orrings in the nucleus of the primary, depending on orbital parameters. Wenote implications of these findings for the production of polar ringsand the onset of nuclear activity in galaxies.
| 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.
| An 18-cm OH and 21-cm H I survey of luminous far-infrared galaxies. II - H I properties
As a part of the present 18-cm OH and 21-cm H I survey of luminousfar-infrared galaxies, the paper provides H I data obtained at Nancayfor 88 IRAS galaxies, with FIR luminosity above 10 to the 10th solarluminosity. Among them, 64 are measured here for the first time. Whenrestricting to radial velocities smaller than 11,000 km/s, the detectionrate is equal to 85 percent, independent of the distance. These galaxiesappear as giant ones in dimension, total mass and total blue luminosity.All these parameters increase with increasing FIR luminosity. ExtremeFIR luminosity is thus related to gigantism, which could be the resultof mergers. These galaxies are also deficient in their relative H Icontent, in the sense that their global relative H I content issignificantly smaller than in classical galaxies of the Hubble sequence.
| The cluster of galaxies SC 2008-57 (A 3667).
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1990RMxAA..21...52S&db_key=AST
| Shell structure associated with the starburst galaxy Markarian 717
The discovery of a shell structure associated with the starburst-nucleusgalaxy Markarian 717 (= IC2551) is reported. V-, R-, and I-band imagesof Mrk 717 are presented. The surface photometry shows that thebrightness profile of Mrk 717 can be described by de Vaucouleurs' r exp1/4 law, implying a spheroidal structure.
| The Wasilewski sample of emission-line galaxies - Follow-up CCD imaging and spectroscopic and IRAS observations
The results of an extensive imaging and spectroscopic follow-up of theobjective prism-selected emission line galaxy (ELG) sample of Wasilewski(1982) are presented. Fluxes at 12, 25, 60, and 100 microns were alsoobtained from the coadded IRAS survey data. ELGs found by objectiveprism surveys are found to be generally small and underluminous galaxieswhich usually have higher than average optical surface brightness. TheSeyfert detection rate in objective prism surveys is roughly 10 percentand the ratio of the space densities of Seyfert 2 to Seyfert 1 galaxiesis significantly larger than unity. Most of the galaxies selected byobjective prism surveys are star-forming, late-type spirals which oftenshow disturbed morphology. About 25 percent of the galaxies detected bythe surveys are faint, high-excitation metal-poor compact H II regions.
| A model for far-IR emission of non-Seyfert Markarian galaxies
The paper presents simple models for the FIR emission from extended H IIregions and from cooler dust heated by the general interstellarradiation field. The models account for a realistic grain-sizedistribution including PAH molecules. In addition, the model explainsthe observed correlation between the FIR to optical luminosity ratio andthe 60-10 micron colors.
| A statistical study of properties of Seyfert and starburst galaxies
Spectral and morphological data for 282 Seyfert and emission-linegalaxies spanning radio to X-ray wavelengths are compiled. The datainclude a large number of optical emission-line measurements which havenot been reported previously. These data are intended to provide aconvenient summary of the relevant properties of these galaxies, as wellas a data base to search for correlations among the various parametersin order to obtain a better understanding of the active galaxyphenomenon. The paper presents the data and analyzes the distributionsof various properties of Seyfert 1 and Seyfert 2 galaxies and starburstgalaxies. It is found that Seyferts 2s have a higher 60 micron/forbiddenO III 5007 A flux ratio than Seyfert 1s. This result, combined with thefact that Seyfert 2s are more heavily reddened, indicate that they havea higher dust content. It is also found that starburst nuclei arecomparable to Seyfert 2s in far-infrared and 20 cm luminosities,although their optical spectra are markedly different.
| Line width-luminosity correlation for starburst galaxies
High-resolution spectroscopy and R-band CCD imagery are used to studythe kinematics of galaxies with starburst nuclei. Good correlations arefound between nuclear H-alpha emission line width and luminosity of thenucleus, and line width and host galaxy luminosity. The fundamentalcorrelation appears to be with the nucleus, but the slope is shallowerthan the Tully-Fisher relation. This makes it a potentially moresensitive luminosity indicator.
| The relative number of Seyfert 2 galaxies. I - Spectra of emission-line galaxies in the Wasilewski field
Slit spectra were obtained of all the Seyfert galaxy candidates and manyother emission-line galaxies discovered by Wasilewski (1982), and theresults are reported. Relative emission line fluxes, redshifts andextinctions, emission line widths and diagnostic ratios, and spectralscans are shown. An activity classification of the galaxies is made. Itis confirmed that the relative number of Seyfert 2 galaxies down to agiven apparent magnitude is large in H II region. Per unit volume ofspace, the relative number of Seyfert (1 + 1.5) to Seyfert (1.8 + 1.9)to Seyfert 2 is approximately 0.1/0.1/0.8.
| Far-infrared luminosities of Markarian starburst galaxies. II - Individual galaxies
IRAS observations of galaxies in the Balzano sample of opticallyselected starburst nuclei and of a comparison of Virgo spiral galaxiesare used to derive far-infrared luminosities. Distances and blue andH-alpha luminosities of the starburst galaxies are also tabulated.
| A study of a flux-limited sample of IRAS galaxies
Redshift data and accurate four-color infrared photometry are presentedfor a complete IRAS sample of galaxies brighter than 2 Jy at 60 microns.A simple power law provides a good fit to the distribution forluminosities from 10 to the 10th to 10 to the 12th solar. There is noindication of an exponential dropoff in the luminosity function at highenergies. A flattening of the luminosity function occurs at L less than10 to the 20th solar. The highest luminosity galaxies typically arefound in multiple, possibly interacting, systems and exhibit marginallynarrower infrared spectral energy distributions than the isolatedspirals which predominate at low luminosities. Infrared-bright galaxiescome from a different population than the majority of optically brightgalaxies. In particular, galaxies of low blue luminosity are not stronginfrared emitters.
| IRAS observations of starburst and nonactive spiral galaxies
Far-infrared properties of starburst, Seyfert II, and nonactive spiralgalaxies are analyzed using IRAS observations at 25, 60, and 100microns. Both starburst galaxies and nonactive spirals concentrate in asmall area in IR color-color diagrams. These observed colors can beinterpreted in terms of a cool (about 30 K) disk component plus a warm(about 80-90 K) component. The total IR luminosities of the starburstgalaxies range from 10 to the 10th to 10 to the 12th solar luminosities,while the upper limit of nonactive spiral galaxies is about 10 the 11thsolar luminosities. The IR color of the starburst galaxies is that of anormal spiral galaxy plus a larger warm component contribution. The 60micron flux is 10-20 percent larger than in the nonactive spirals ofthis sample. The fraction of 60-micron emission attributable to the warmcomponent can be used as an indicator for the star-formation activity ingalaxies.
| Neutral hydrogen in starburst galaxies
A survey of neutral-hydrogen 21 cm emission from a sample of starburstgalaxies was conducted in order to derive their global properties. Ofthe 72 galaxies surveyed, H I was detected in 47. Average mass-to-lightratios log (MH/Lpg) = -0.7 + or - 0.4 and log (MT/Lpg) = 0.5 + or - 0.4.The masses and luminosities span the range 10 to the 10th-12th solarmasses and 10 to the 9th-11th solar luminosities, typical of normal latespirals. The starburst activity, as measured by the luminosity of theH-alpha line, correlates roughly with the mass of atomic hydrogen, thetotal mass, and the total photographic luminosity of the host galaxy. Itis suggested that the occurrence of a nuclear starburst and the strengthof such an event probably do not depend strongly on the large-scaleproperties of the galaxy.
| 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.
| A Study of the Largescale Structure in the Distribution of Galaxies in a Region Centered about the Cancer Cluster - Part Two - Further Observational Results
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1986AJ.....91..732B&db_key=AST
| Star-burst galactic nuclei
Markarian (1967) has conducted a survey of galaxies having strongultraviolet continua. In connection with this survey, a new group ofgalaxies was discovered which could provide additional insight into thenature and evolution of active galactic nuclei. The optical morphologyof the discovered galaxies is similar to that shown by Seyfert galaxies,with dominant feature often being a bright, starlike nucleus. However,these nuclei do not usually display the broad emission-line spectra socharacteristic of the Seyferts. Their narrow emission features and otherobservable properties can be explained by the presence of a hot, youngstar population. For this reason, these objects have become known asstar-burst nuclei. The nuclear star-burst phenomenon might supplymaterial for gravitational accretion, and, therefore, for thedevelopment of active galaxies. Balzano and Weedman (1981) have studiedthese nuclei as a distinct group. The present investigation representsthe first comprehensive survey.
| Redshifts of 16 Markarian galaxies
Redshifts measured for 16 previously unstudied Markarian galaxies arepresented. The galaxies, from the eighth and ninth Markarian lists, wereobserved with an image dissector scanner on the 1.8-m Perkins telescopeat the Lowell Observatory at low and moderate resolution betweenwavelengths of 4500 and 7200 A. Of the 16 galaxies observed, no emissionfeatures or reliable absorption features were detected in the spectra ofMrk 713, Mrk 760 or Mrk 866, and Mrk 712 and Mrk 800 showed spectralfeatures suggestive of high-excitation emission-line galaxies. Two pairsof galaxies, Mrk 775/Mrk 776 and Mrk 827/Mrk 828, were observed whichhad redshifts so close as to suggest a physical association, andestimates of the minimum mass of these systems were obtained.
| Accurate optical positions for Markarian objects 701-797
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1980AJ.....85.1328F&db_key=AST
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