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|INTEGRAL and RXTE Observations of Centaurus A|
INTEGRAL and RXTE performed three simultaneous observations of thenearby radio galaxy Centaurus A in 2003 March, 2004 January, and 2004February with the goals of investigating the geometry and emissionprocesses via the spectral/temporal variability of the X-ray/low-energygamma-ray flux, and intercalibration of the INTEGRAL instruments withrespect to those on RXTE. Cen A was detected by both sets of instrumentsfrom 3 to 240 keV. When combined with earlier archival RXTE results, wefind the power-law continuum flux and the line-of-sight column depthvaried independently by 60% between 2000 January and 2003 March.Including the three archival RXTE observations, the iron-line flux wasessentially unchanging, and from this we conclude that theiron-line-emitting material is distant from the site of the continuumemission, and that the origin of the iron-line flux is still an openquestion. Taking X-ray spectral measurements from satellite missionssince 1970 into account, we discover a variability in the column depthbetween 1.0×1023 and 1.5×1023cm-2 separated by approximately 20 yr, and suggest thatvariations in the edge of a warped accretion disk viewed nearly edge-onmight be the cause. The INTEGRAL OSA 4.2 calibration of JEM-X, ISGRI,and SPI yields power-law indices consistent with the RXTE PCA and HEXTEvalues, but the indices derived from ISGRI alone are about 0.2 greater.Significant systematics are the limiting factor for INTEGRAL spectralparameter determination.
|Extending the Search for Counterrotating Gas and Stars in Galaxies: A Study of Late-Type Dwarfs|
In a previous study on gas-stellar counterrotation for a large sample ofE/S0 and spiral galaxies (Kannappan & Fabricant 2001), two dwarfirregular galaxies were included, of which one was tentativelyidentified as a counterrotator. Here we extend the search forcounterrotation to include 10 more irregular/spiral dwarf galaxies. Wefind that all systems with well defined gas and stellar rotation showkinematics consistent with co-rotation. However, we see evidence ofdecoupled gas and stellar kinematics in ≳ 50% of the sample,possibly reflecting minor interactions too small to create large-scalegas-stellar counterrotation.
|The Molecular Interstellar Medium of Dwarf Galaxies on Kiloparsec Scales: A New Survey for CO in Northern, IRAS-detected Dwarf Galaxies|
We present a new survey for CO in dwarf galaxies using the ARO Kitt Peak12 m telescope. This survey consists of observations of the centralregions of 121 northern dwarfs with IRAS detections and no known COemission. We detect CO in 28 of these galaxies and marginally detectanother 16, increasing by about 50% the number of such galaxies known tohave significant CO emission. The galaxies we detect are comparable instellar and dynamical mass to the Large Magellanic Cloud, althoughsomewhat brighter in CO and fainter in the far-IR. Within dwarfs, wefind that the CO luminosity LCO is most strongly correlatedwith the K-band and the far-infrared luminosities. There are also strongcorrelations with the radio continuum (RC) and B-band luminosities andlinear diameter. Conversely, we find that far-IR dust temperature is apoor predictor of CO emission within the dwarfs alone, although a goodpredictor of normalized CO content among a larger sample of galaxies. Wesuggest that LCO and LK correlate well because thestellar component of a galaxy dominates the midplane gravitational fieldand thus sets the pressure and density of the atomic gas, which controlthe formation of H2 from H I. We compare our sample with moremassive galaxies and find that dwarfs and large galaxies obey the samerelationship between CO and the 1.4 GHz RC surface brightness. Thisrelationship is well described by a Schmidt law withΣRC~Σ1.3CO. Therefore,dwarf galaxies and large spirals exhibit the same relationship betweenmolecular gas and star formation rate (SFR). We find that this result isrobust to moderate changes in the RC-to-SFR and CO-to-H2conversion factors. Our data appear to be inconsistent with large (orderof magnitude) variations in the CO-to-H2 conversion factor inthe star-forming molecular gas.
|The Westerbork HI survey of spiral and irregular galaxies. III. HI observations of early-type disk galaxies|
We present Hi observations of 68 early-type disk galaxies from the WHISPsurvey. They have morphological types between S0 and Sab and absoluteB-band magnitudes between -14 and -22. These galaxies form the massive,high surface-brightness extreme of the disk galaxy population, few ofwhich have been imaged in Hi before. The Hi properties of the galaxiesin our sample span a large range; the average values of MHI/LB and DH I/D25 are comparableto the ones found in later-type spirals, but the dispersions around themean are larger. No significant differences are found between the S0/S0aand the Sa/Sab galaxies. Our early-type disk galaxies follow the same Himass-diameter relation as later-type spiral galaxies, but theireffective Hi surface densities are slightly lower than those found inlater-type systems. In some galaxies, distinct rings of Hi emissioncoincide with regions of enhanced star formation, even though theaverage gas densities are far below the threshold of star formationderived by Kennicutt (1989, ApJ, 344, 685). Apparently, additionalmechanisms, as yet unknown, regulate star formation at low surfacedensities. Many of the galaxies in our sample have lopsided gasmorphologies; in most cases this can be linked to recent or ongoinginteractions or merger events. Asymmetries are rare in quiescentgalaxies. Kinematic lopsidedness is rare, both in interacting andisolated systems. In the appendix, we present an atlas of the Hiobservations: for all galaxies we show Hi surface density maps, globalprofiles, velocity fields and radial surface density profiles.
|Catalog of Double Nucleus Disk Galaxies|
We have compiled a catalog of disk galaxies that have a double nucleus,through systematic examination of existing catalogs and publications.The Catalog of Double Nucleus Disk Galaxies includes 107 objects,together with their basic data. The aim of the catalog is to provide amore systematic and homogeneous basis for the study of the relevance ofgalaxy interactions and minor mergers in the formation of these doublenuclei. We have also investigated possible correlations betweengeometric and photometric parameters of the double nuclei and their hostgalaxies. The preliminary results indicate the presence of severalsignificant correlations that should be considered in any theoreticalscenario describing minor mergers and disk galaxy evolution.
|[O II] as a Star Formation Rate Indicator|
We investigate the [O II] emission line as a star formation rate (SFR)indicator using integrated spectra of 97 galaxies from the Nearby FieldGalaxies Survey (NFGS). The sample includes all Hubble types andcontains SFRs ranging from 0.01 to 100 Msolaryr-1. We compare the Kennicutt [O II] and Hα SFRcalibrations and show that there are two significant effects thatproduce disagreement between SFR([O II]) and SFR(Hα): reddeningand metallicity. Differences in the ionization state of the interstellarmedium do not contribute significantly to the observed differencebetween SFR([O II]) and SFR(Hα) for the NFGS galaxies withmetallicities log(O/H)+12>~8.5. The Kennicutt [O II]-SFR relationassumes a typical reddening for nearby galaxies; in practice, thereddening differs significantly from sample to sample. We derive a newSFR([O II]) calibration that does not contain a reddening assumption.Our new SFR([O II]) calibration also provides an optional correction formetallicity. Our SFRs derived from [O II] agree with those derived fromHα to within 0.03-0.05 dex. We show that the reddening, E(B-V),increases with intrinsic (i.e., reddening-corrected) [O II] luminosityfor the NFGS sample. We apply our SFR([O II]) calibration withmetallicity correction to two samples: high-redshift 0.8
|The Hα and Infrared Star Formation Rates for the Nearby Field Galaxy Survey|
We investigate the Hα and infrared star formation rate (SFR)diagnostics for galaxies in the Nearby Field Galaxy Survey (NFGS). Forthe 81 galaxies in our sample, we derive Hα fluxes (included here)from integrated spectra. There is a strong correlation between the ratioof far-infrared to optical luminosities L(FIR)/L(Hα) and theextinction E(B-V) measured with the Balmer decrement. Before reddeningcorrection, the SFR(IR) and SFR(Hα) are related to each other by apower law: SFR(IR)=(2.7+/-0.3)SFR(Hα)1.30+/-0.06.Correction of the SFR(Hα) for extinction using the Balmerdecrement and a classical reddening curve both reduces the scatter inthe SFR(IR)-SFR(Hα) correlation and results in a much closeragreement between the two SFR indicators;SFR(IR)=(0.91+/-0.04)SFR(Hαcorr)1.07+/-0.03.SFR(IR) and SFR(Hα) agree to ~10%. This SFR relationship spans 4orders of magnitude and holds for all Hubble types with IRAS detectionsin the NFGS. A constant ratio between the SFR(IR) and SFR(Hα) forall Hubble types, including early types (S0-Sab), suggests that the IRemission in all these objects results from a young stellar population.
|An H I Survey of Actively Star-forming Dwarf Galaxies|
We present the results of H I 21 cm observations of 139 activelystar-forming dwarf galaxies obtained with the 305 m radio telescope atArecibo Observatory. Our sample consists of all objects cataloged inobjective-prism surveys for UV-excess or emission-line galaxiespublished prior to the start of the survey that have luminosities belowMB=-17.0 and that are located within the declination limitsof the Arecibo telescope. Galaxies from the Markarian, Michigan, Case,Wasilewski, Haro, and Zwicky lists are included. The sample spans a widerange of both H I gas content and star formation levels. A total of 122objects (88%) were detected; 82 galaxies have been observed for thefirst time in H I. The median velocity width for our sample is 88 kms-1, and the median H I gas mass is 3.0×108Msolar. In general, the sample galaxies are gas-rich, with anaverage MHI/LB=1.3 after correcting for theluminosity enhancement due to the starburst. The progenitors of many ofthe star-forming dwarfs have higher MHI/LB thantypically seen in samples of nearby ``normal'' galaxies, emphasizingtheir distinct nature.
|The UZC-SSRS2 Group Catalog|
We apply a friends-of-friends algorithm to the combined Updated ZwickyCatalog and Southern Sky Redshift Survey to construct a catalog of 1168groups of galaxies; 411 of these groups have five or more members withinthe redshift survey. The group catalog covers 4.69 sr, and all groupsexceed the number density contrast threshold, δρ/ρ=80. Wedemonstrate that the groups catalog is homogeneous across the twounderlying redshift surveys; the catalog of groups and their membersthus provides a basis for other statistical studies of the large-scaledistribution of groups and their physical properties. The medianphysical properties of the groups are similar to those for groupsderived from independent surveys, including the ESO Key Programme andthe Las Campanas Redshift Survey. We include tables of groups and theirmembers.
|The Morphologies of Dwarf Markarian Galaxies|
The morphologies of the 96 dwarf (M(B) -17m) galaxies in the Markariancatalog are determined from the digitized Schmidt plates obtained forthe construction of the Hubble Space Telescope Guide Star Catalog. Thefraction of double nucleus galaxies within the dwarf Markarian galaxiesis determined to be twice that found for all galaxies in the Markariancatalog. In addition to the 12 previously known cases, four definite andtwo probable galaxies with double nuclei are identified. The fraction ofdwarf Markarian galaxies with bright star forming regions is found to betwice that of Virgo cluster dwarf galaxies. No Elliptical galaxies arefound in the sample. Galaxies with blue compact dwarf and S0morphologies are more often found to contain unresolved regions of UVexcess emission. Dwarf Markarian galaxies with different morphologicalstructures and spectral classes are found to have similar FIRproperties.
|Spectrophotometry of Nearby Field Galaxies: The Data|
We have obtained integrated and nuclear spectra as well as U, B, Rsurface photometry for a representative sample of 196 nearby galaxies.These galaxies span the entire Hubble sequence in morphological type, aswell as a wide range of luminosities (MB=-14 to -22). Here wepresent the spectrophotometry for these galaxies. The selection of thesample and the U, B, R surface photometry is described in a companionpaper. Our goals for the project include measuring the current starformation rates and metallicities of these galaxies, and elucidatingtheir star formation histories, as a function of luminosity andmorphology. We thereby extend the work of Kennicutt to lower luminositysystems. We anticipate that our study will be useful as a benchmark forstudies of galaxies at high redshift. We describe the observing, datareduction, and calibration techniques and demonstrate that ourspectrophotometry agrees well with that of Kennicutt. The spectra spanthe range 3550-7250 Å at a resolution (FWHM) of ~6 Å andhave an overall relative spectrophotometric accuracy of ~+/-6%. Wepresent a spectrophotometric atlas of integrated and nuclear rest-framespectra as well as tables of equivalent widths and synthetic colors. Theatlas and tables of measurements will be made available electronically.We study the correlations of galaxy properties determined from thespectra and images. Our findings include: (1) galaxies of a givenmorphological class display a wide range of continuum shapes andemission-line strengths if a broad range of luminosities are considered,(2) emission-line strengths tend to increase and continua tend to getbluer as the luminosity decreases, and (3) the scatter on the generalcorrelation between nuclear and integrated Hα emission-linestrengths is large.
|Surface Photometry of Nearby Field Galaxies: The Data|
We have obtained integrated spectra and multifilter photometry for arepresentative sample of ~200 nearby galaxies. These galaxies span theentire Hubble sequence in morphological type, as well as a wide range ofluminosities (MB=-14 to -22) and colors (B-R=0.4-1.8). Herewe describe the sample selection criteria and the U, B, R surfacephotometry for these galaxies. The spectrophotometric results will bepresented in a companion paper. Our goals for the project includemeasuring the current star formation rates and metallicity of thesegalaxies, and elucidating their star formation histories, as a functionof luminosity and morphology. We thereby extend the work of Kennicutt tolower luminosity systems. We anticipate that our study will be useful asa benchmark for studies of galaxies at high redshift. We discuss theobserving, data reduction, and calibration techniques and show that ourphotometry agrees well with previous work in those cases in whichearlier data are available. We present an atlas of images, radialsurface brightness profiles, and color profiles as well as tables ofderived parameters. The atlas and tables of measurements will be madeavailable electronically. We study the correlations of galaxy propertiesdetermined from the galaxy images. Our findings include the following:(1) colors determined within the effective radius correlate better withmorphological type than with MB and (2) 50% of thelow-luminosity galaxies are bluest in their centers.
|Nearby Optical Galaxies: Selection of the Sample and Identification of Groups|
In this paper we describe the Nearby Optical Galaxy (NOG) sample, whichis a complete, distance-limited (cz<=6000 km s-1) andmagnitude-limited (B<=14) sample of ~7000 optical galaxies. Thesample covers 2/3 (8.27 sr) of the sky (|b|>20deg) andappears to have a good completeness in redshift (97%). We select thesample on the basis of homogenized corrected total blue magnitudes inorder to minimize systematic effects in galaxy sampling. We identify thegroups in this sample by means of both the hierarchical and thepercolation ``friends-of-friends'' methods. The resulting catalogs ofloose groups appear to be similar and are among the largest catalogs ofgroups currently available. Most of the NOG galaxies (~60%) are found tobe members of galaxy pairs (~580 pairs for a total of ~15% of objects)or groups with at least three members (~500 groups for a total of ~45%of objects). About 40% of galaxies are left ungrouped (field galaxies).We illustrate the main features of the NOG galaxy distribution. Comparedto previous optical and IRAS galaxy samples, the NOG provides a densersampling of the galaxy distribution in the nearby universe. Given itslarge sky coverage, the identification of groups, and its high-densitysampling, the NOG is suited to the analysis of the galaxy density fieldof the nearby universe, especially on small scales.
|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.
|Study of New Sample of Candidate Blue Compact Dwarf Galaxies. HI Observations of 73 Objects at Nancay Radio Telescope|
|New catalogue of Wolf-Rayet galaxies and high-excitation extra-galactic HII regions|
We present a new compilation of Wolf-Rayet (WR) galaxies andextra-galactic Hii regions showing broad He ii lambda 4686 emissiondrawn from the literature. Relevant information on the presence of otherbroad emission lines ([N i] lambda 5199ii, C iv lambda 5808 and others)from WR stars of WN and WC subtypes, and other existing broad nebularlines is provided. In total we include 139 known WR galaxies. Amongthese, 57 objects show both broad He ii lambda 4686 and C iv lambda 5808features. In addition to the broad (stellar) He ii lambda 4686 emission,a nebular He ii component is well established (suspected) in 44 (54)objects. We find 19 extra-galatic Hii regions without WR detectionsshowing nebular He ii lambda 4686 emission. The present sample can beused for a variety of studies on massive stars, interactions of massivestars with the ISM, stellar populations, starburst galaxies etc. Thedata is accessible electronically and will be updated periodically. Thecatalogue is available at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (188.8.131.52) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
|Groups of galaxies. III. Some empirical characteristics.|
|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.
|Imaging and Spectroscopic Observations of the Case Survey Blue/Emission- Line Galaxies|
We present CCD imaging and spectroscopic data for 176 blue and/oremission-line galaxies from Lists I and II of the Case Northern SkySurvey. Our sample consists of all Case galaxies which lie in the regionwhich overlaps the original Slice of the Universe survey. We use theobservational data to investigate the physical properties of thegalaxies selected by the survey, to compare with various parameterspublished in the survey lists, and to investigate the selectioncharacteristics and completeness limit of the survey. The majority ofthe Case galaxies are energized by regions of active star formation;only 5% of the sample are Seyfert galaxies. The dual selectiontechniques used (both UV-excess and emission lines) allow the survey todetect star-forming galaxies with a wide range of properties andevolutionary states. In particular, the Case survey selects galaxieswith lower levels of activity than most previous surveys. The surveyalso includes a larger fraction of intermediate and low-luminositygalaxies than would be present in a purely magnitude- limited sample.Although galaxies as faint as m_B_ = 19 are present in the sample, thecompleteness limit of the UV-excess selected portion of the survey iscloser to m_B_ = 16. The luminosity function of the Case galaxies isderived and compared with that of the "normal" field galaxies in thesame volume of space. The shape of the Case luminosity function issimilar to that for the field sample. A surprising result is that 31% ofthe field galaxy population can be accounted for by galaxies of the typeselected in the Case survey.
|Optical imaging and long-slit spectroscopy of Markarian galaxies with multiple nuclei. I - Basic data|
Optical CCD images and long-slit spectroscopic data are presented forover 100 Markarian (UV-excess) galaxies reported in early studies topossess multiple optical nuclei or extreme morphological peculiaritiessuggestive of galaxy collisions and mergers. Stacked broad-band imagesare presented with histogram equalization in order to showsimultaneously the nuclei and features at very low surface-brightnesslevels. Morphological properties, luminosities and colors of theintegral systems are given. Photometric and image properties of over 200individual nuclei and giant H II regions have been measured with respectto the local backgrounds in the galaxies using an objective imagefinding algorithm. Labeled contour plots identify the measuredsubcomponents. Two-dimensional spectral data are presented, in additionto intensity profiles along the slit in the light of H-alpha + forbiddenN II emission lines and adjacent continuum. Nuclear emission-linemeasurements, reddening estimates, monochromatic continuum magnitudes,and colors are given.
|A revised catalog of CfA1 galaxy groups in the Virgo/Great Attractor flow field|
A new identification of groups and clusters in the CfA1 Catalog ofHuchra et al. is presented, using a percolation algorithm to identifydensity enhancements. It is shown that in the resulting catalog,contamination by interlopers is significantly reduced. The Schechterluminosity function is redetermined, including the Malmquist bias.
|General study of group membership. II - Determination of nearby groups|
We present a whole sky catalog of nearby groups of galaxies taken fromthe Lyon-Meudon Extragalactic Database. From the 78,000 objects in thedatabase, we extracted a sample of 6392 galaxies, complete up to thelimiting apparent magnitude B0 = 14.0. Moreover, in order to considersolely the galaxies of the local universe, all the selected galaxieshave a known recession velocity smaller than 5500 km/s. Two methods wereused in group construction: a Huchra-Geller (1982) derived percolationmethod and a Tully (1980) derived hierarchical method. Each method gaveus one catalog. These were then compared and synthesized to obtain asingle catalog containing the most reliable groups. There are 485 groupsof a least three members in the final catalog.
|A list of some corrections to Zwicky's Catalogue of Galaxies and Clusters of Galaxies|
|Spectral investigation of the dwarf galaxy Markarian 773|
A spectral investigation of the galaxy Markarian 773 is carried out onthe basis of spectral observations. It is shown that Markarian 773 is ablue compact dwarf galaxy with an iE morphological classification. Thenuclear nature of the condensations identified in the galaxy was notproven. The brightest condensation located outside the central region ofthe galaxy is the giant HII region with a high star formation rate. Thetwo other condensations are ordinary HII regions. The giant HII regionis a younger formation. It is suggested that star formation takes placealong the galaxy's entire body.
|Radio and infrared emission from Markarian starburst galaxies|
Radio and infrared emission were compared for a sample of 58 Markarianstarburst galaxies, chosen to cover a wide range of 60-micron luminositydensity. New radio observations were from the VLA at 6 and 20 cm in theB and A configurations. IRAS data were reanalyzed for 25 of thestarbursts that were previously undetected at either 25 or 100 microns.The correlation between the global radio and IR emission for thestarbursts in the sample is strongest at 25 and 60 microns, wavelengthsin which the warm dust dominates. The radio spectral index steepens awayfrom the center. This indicates that nonthermal emission leaks out ofthe starburst region. The change in the spectral index implies thatwhile nonthermal sources dominate in the entire region, the bulk of theinterior emission at 6 cm is thermal. The radio spectral index does notappear to vary as a function of the infrared luminosity or the infraredcolors, which indicates that the slope of the initial mass function doesnot appear to be a function of either the mass or temperature of thestarburst.
|Far-infrared luminosity functions of normal galaxies|
A volume-limited sample is constructed from the Zwicky catalog and IRASdata base to examine the FIR luminosity functions of normal galaxies,and to investigate possible relationships between FIR emission andgalaxy morphology. Quantitative and unbiased treatment is provided by'survival analysis' statistical methods. It is found that the FIRdistributions of normal galaxies are better fit by lognormal thanSchechter functions. The total FIR emissivity (8 to 115 microns) ofnormal galaxies is approximately equal to half their emission in the Bplus V optical bands. Normal galaxy FIR emission is uncorrelated withthe basic S0-Sm Hubble sequence of spiral galaxy morphology, but appearsto be affected by de Vaucouleurs' (1959) revised morphologicalclassifications based on inner rings and S-shaped arms. Spirals withbars and inner rings are systematically fainter than unbarred spirals.It is suggested that bars and rings reduce the amount or spatiallyconfine the dust in spiral disks, resulting in lower efficiencyconversion of optical and UV photons into the IR.
|The far-infrared properties of the CfA galaxy sample. I - The catalog|
IRAS flux densities are presented for all galaxies in the Center forAstrophysics magnitude-limited sample (mB not greater than 14.5)detected in the IRAS Faint Source Survey (FSS), a total of 1544galaxies. The detection rate in the FSS is slightly larger than in thePSC for the long-wavelength 60- and 100-micron bands, but improves by afactor of about 3 or more for the short wavelength 12- and 25-micronbands. This optically selected sample consists of galaxies which are, onaverage, much less IR-active than galaxies in IR-selected samples. Itpossesses accurate and complete redshift, morphological, and magnitudeinformation, along with observations at other wavelengths.
|Far-infrared properties of Markarian galaxies with multiple nuclei - Warm dust emission in mergers|
An investigation of coadded IRAS data is performed on 187 Markariangalaxies where distinguishing morphological characteristics or multipleoptical nuclei are present. The far-IR properties of Markarian galaxiesare compared to the IRAS Bright Galaxy Sample, and a much higher mediandust temperature is found in the multiple nucleus galaxies, suggestingthat more far-IR luminosity results from active star formation. Bothoptical/UV and far-IR selection techniques are necessary to extractcomplete samples of AGNs since the far-IR two-color plane can miss up to50 percent of the galaxies. A systematic increase in the contribution ofwarm dust emission due to active star formation and AGNs is found in astatistical comparison of merger candidates and other galaxy samples.The assumed nature of precursor galaxies determines the assumedenhancement of far-IR luminosity caused by galaxy collisions. A model ispresented which describes the properties of the Markarian galaxies interms of enhanced OB star formation and different grain sizedistributions. The results of the investigation are shown to beconsistent with a 'subdued' interpretation of merging galaxies with highluminosities.
|Objective prism survey of emission-line galaxies. IV|
The results of an objective prism survey of emission-line galaxies usingthe Beijing Observatory 60-cm Schmidt are given. The survey includes 100emission-line objects, of which 96 are emission-line galaxies, 3 areplanetary nebulae and 1 is an emission-line star. Of the emission-linegalaxies, 69-72 percent are of types s or sd; 27-28 percent are of typesd and ds. In addition to 4 known Seyfert galaxies, there are at least 5probable Seyferts. Twenty-three of the objects are IRAS sourcescharacterized by strong emission phenomena.
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