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The AMIGA sample of isolated galaxies. VII. Far-infrared and radio continuum study of nuclear activity
Context: This paper is part of a series involving the AMIGA project(Analysis of the Interstellar Medium of Isolated GAlaxies). This projectprovides a statistically-significant sample of the most isolatedgalaxies in the northern sky. Aims: We present a study of the nuclearactivity in a well-defined sample of the most isolated galaxies (totalsample: n = 1050, complete subsample: n = 719) in the local Universetraced by their far-infrared (FIR) and radio continuum emission. Methods: We use the well-known radio continuum-FIR correlation to selectradio-excess galaxies that are candidates to host an active galacticnucleus (AGN), as well as the FIR colours to find obscuredAGN-candidates. We also used the existing information on nuclearactivity in the Véron-Cetty catalogue and in the NASAExtragalactic Database. Results: A final catalogue of AGN-candidategalaxies has been produced that will provide a baseline for studies onthe dependence of activity on the environment. Our sample is mostlyradio quiet, consistent with its high content of late-type galaxies. Atmost ~1.5% of the galaxies show a radio excess with respect to theradio-FIR correlation, and this fraction even goes down to less than0.8% after rejection of back/foreground sources using FIRST. We findthat the fraction of FIR colour selected AGN-candidates is ~28% with alower limit of ~7% Our final catalogue contains 89 AGN candidates and ispublicly available on the AMIGA web page(http://www.iaa.csic.es/AMIGA.html). A comparison with the results fromthe literature shows that the AMIGA sample has the lowest ratio of AGNcandidates, both globally and separated into early and late types. Fieldgalaxies as well as poor cluster and group environments showintermediate values, while the highest rates of AGN candidates are foundin the central parts of clusters and in pair/merger dominated samples.For all environments, early-type galaxies show a higher ratio ofradio-excess galaxies than late types, as can be expected, since massiveelliptical galaxies are the usual hosts of powerful radio continuumemission. Conclusions: We conclude that the environment plays a crucialand direct role in triggering radio nuclear activity and not only viathe density-morphology relation. Isolated, early-type galaxies show aparticularly low level of activity at radio wavelengths henceconstituting the most nurture-free population of luminous early-typegalaxies.Full Tables 1, 2, 4-6 are available in electronic form athttp://www.iaa.csic.es/AMIGA.html and at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/486/73
| The AMIGA sample of isolated galaxies. VI. Radio continuum properties of isolated galaxies: a very radio-quiet sample
Context: This paper is part of a series that describes the results ofthe AMIGA (Analysis of the interstellar Medium of Isolated GAlaxies)project, studying the largest sample of very isolated galaxies in thelocal Universe. Aims: The study of the radio properties of the AMIGAsample is intended to characterize the radio continuum emission for asample least affected by the local environment, thus providing areference against which less isolated and interacting samples can becompared. Methods: Radio continuum data at 325, 1420, and 4850 MHzwere extracted from the WENSS, NVSS/FIRST, and GB6 surveys,respectively. The source extractions have been obtained fromreprocessing the data and new detections added to the cross-matcheddetections with the respective survey catalogs. We focus on the completeAMIGA subsample composed of 719 galaxies. Results: A catalog of radiofluxes was obtained from the above four surveys. Comparison between theNVSS and FIRST detections indicates that the radio continuum is comingfrom disk-dominated emission in spiral galaxies, in contrast to theresults found in high-density environments where nuclear activity ismore frequent. The comparison of the radio continuum power with acomparable sample, which is however not selected with respect to itsenvironment, the Condon et al. UGC-SF sample of starforming fieldgalaxies, shows a lower mean value for the AMIGA sample. We haveobtained radio-to-optical flux ratios (R) using the NVSS radio continuumflux. The distribution of R for the AMIGA galaxies is consistent with asample dominated by radio emission from star formation (SF) and a smallnumber of active galactic nuclei (AGN), with less than 3% of the samplewith R > 100. We derived the radio luminosity function (RLF) andtotal power density of the radio continuum emission for the AMIGA sampleat 1.4 GHz, and compared them with results from other low-redshiftstudies. The Schechter fit of the RLF indicates a major weight of thelow-luminosity galaxies. Conclusions: The results indicate the verylow level of radio continuum emission in our sample of isolatedgalaxies, which is dominated by mild disk SF. It confirms thus the AMIGAsample as a suitable template to effectively quantify the role ofinteractions in samples extracted from denser environments.Full Table 2 is only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/485/475
| The AMIGA sample of isolated galaxies. V. Quantification of the isolation
Context: The AMIGA project aims to build a well defined andstatistically significant reference sample of isolated galaxies in orderto estimate the environmental effects on the formation and evolution ofgalaxies. Aims: The goal of this paper is to provide a measure of theenvironment of the isolated galaxies in the AMIGA sample, quantifyingthe influence of the candidate neighbours identified in our previouswork and their potential effects on the evolution of the primarygalaxies. Here we provide a quantification of the isolation degree ofthe galaxies in this sample. Methods: Our starting sample is theCatalogue of Isolated Galaxies (CIG). We used two parameters to estimatethe influence exerted by the neighbour galaxies on the CIG galaxy: thelocal number density of neighbour galaxies and the tidal strengthaffecting the CIG galaxy. We show that both parameters together providea comprehensive picture of the environment. For comparison, thoseparameters have also been derived for galaxies in denser environmentssuch as triplets, groups and clusters. Results: The CIG galaxies show acontinuous spectrum of isolation, as quantified by the two parameters,from very isolated to interacting. The fraction of CIG galaxies whoseproperties are expected to be influenced by the environment is howeverlow (159 out of 950 galaxies). The isolated parameters derived for thecomparison samples gave higher values than for the CIG and we foundclear differences for the average values of the 4 samples considered,proving the sensitivity of these parameters. Conclusions: Theenvironment of the galaxies in the CIG has been characterised, using twocomplementary parameters quantifying the isolation degree, the localnumber density of the neighbour galaxies and the tidal forces affectingthe isolated galaxies. A final catalogue of galaxies has been producedand the most isolated of these galaxies are consequently appropriate toserve as a reference sample for the AMIGA project.Full Tables [see full text], [see full text] and [see full text]-[see full text] are available in electronic form at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/472/121 and fromhttp://www.iaa.es/AMIGA.html.
| The AMIGA sample of isolated galaxies. III. IRAS data and infrared diagnostics
Aims.We describe the mid- (MIR) and far- (FIR) infrared properties of alarge (~1000) sample of the most isolated galaxies in the localUniverse. This sample is intended as a "nurture-free" zero point againstwhich more environmentally influenced samples can be compared. Methods: We reprocess IRAS MIR/FIR survey data using the ADDSCAN/SCANPIutility for 1030 out of 1050 galaxies from the Catalogue of IsolatedGalaxies (CIG) as part of the AMIGA project. We focus on diagnostics(FIR luminosity L_FIR, R=log(L_FIR/LB), and IRAS colours)thought to be sensitive to effects of environment or interaction. Results: The distribution of log(L_FIR) sharply peaks from 9.0-10.5,with very few (<2%) galaxies above 10.5. Review of available opticalimages of the most FIR luminous galaxies finds the majority likely to beinteracting systems missed in our earlier morphological reevaluation.The optically normalised luminosity diagnostic R=log(L_FIR/LB) shows a sharply peaked distribution between 0.0and -1.0. These results were compared to the magnitude limited sample ofthe Center for Astrophysics that was selected without environmentaldiscrimination. This modestly (e.g., compared to cluster, binary galaxy,and compact group samples) environmentally affected sample shows asignificantly higher mean log(L_FIR), and R, whereas the meanlog(LB) is the same. Our sample shows a strong L_FIR vs.LB correlation, with a slope steeper than one (L_FIR ∝LB1.41). Interacting galaxies were found abovethis correlation, showing an enhancement in L_FIR. With respect to theIRAS colours, we found higher F_60/F_100 values for ellipticals andlate-type galaxies than for spirals, indicating a higher dusttemperature. The mean value of F_60/F_100 was found to be lower than forinteracting samples from the literature. Conclusions: .The resultsindicate that the FIR emission is a variable enhanced by interaction,and that our sample probably shows the lowest possible mean value. Thisattests to the utility of our sample for defining a nurture-free zeropoint.
| The AMIGA sample of isolated galaxies. II. Morphological refinement
We present a refinement of the optical morphologies for galaxies in theCatalog of Isolated Galaxies that forms the basis of the AMIGA (Analysisof the interstellar Medium of Isolated GAlaxies) project. Uniformreclassification using the digitized POSS II data benefited from thehigh resolution and dynamic range of that sky survey. Comparison withindependent classifications made for an SDSS overlap sample of more than200 galaxies confirms the reliability of the early vs. late-typediscrimination and the accuracy of spiral subtypes within Δ T =1-2. CCD images taken at the Observatorio de Sierra Nevada were alsoused to solve ambiguities in early versus late-type classifications. Aconsiderable number of galaxies in the catalog (n = 193) are flagged forthe presence of nearby companions or signs of distortion likely due tointeraction. This most isolated sample of galaxies in the local Universeis dominated by two populations: 1) 82% are spirals (Sa-Sd) with thebulk being luminous systems with small bulges (63% between types Sb-Sc)and 2) a significant population of early-type E-S0 galaxies (14%). Mostof the types later than Sd are low luminosity galaxies concentrated inthe local supercluster where isolation is difficult to evaluate. Thelate-type spiral majority of the sample spans a luminosity rangeMB-corr = -18 to -22 mag. Few of the E/S0 population are moreluminous than -21.0 marking the absence of the often-sought superL* merger (e.g. fossil elliptical) population. The rarity ofhigh luminosity systems results in a fainter derived M* forthis population compared to the spiral optical luminosity function(OLF). The E-S0 population is from 0.2 to 0.6 mag fainter depending onhow the sample is defined. This marks the AMIGA sample as unique amongsamples that compare early and late-type OLFs separately. In othersamples, which always involve galaxies in higher density environments,M^*_E/S0 is almost always 0.3-0.5 mag brighter than M^*_S, presumablyreflecting a stronger correlation between M* andenvironmental density for early-type galaxies.
| Supernova 2005cv in UGC 1359
IAUC 8563 available at Central Bureau for Astronomical Telegrams.
| The ISOPHOT 170 μm Serendipity Survey II. The catalog of optically identified galaxies%
The ISOPHOT Serendipity Sky Survey strip-scanning measurements covering≈15% of the far-infrared (FIR) sky at 170 μm were searched forcompact sources associated with optically identified galaxies. CompactSerendipity Survey sources with a high signal-to-noise ratio in at leasttwo ISOPHOT C200 detector pixels were selected that have a positionalassociation with a galaxy identification in the NED and/or Simbaddatabases and a galaxy counterpart visible on the Digitized Sky Surveyplates. A catalog with 170 μm fluxes for more than 1900 galaxies hasbeen established, 200 of which were measured several times. The faintest170 μm fluxes reach values just below 0.5 Jy, while the brightest,already somewhat extended galaxies have fluxes up to ≈600 Jy. For thevast majority of listed galaxies, the 170 μm fluxes were measured forthe first time. While most of the galaxies are spirals, about 70 of thesources are classified as ellipticals or lenticulars. This is the onlycurrently available large-scale galaxy catalog containing a sufficientnumber of sources with 170 μm fluxes to allow further statisticalstudies of various FIR properties.Based on observations with ISO, an ESA project with instruments fundedby ESA Member States (especially the PI countries: France, Germany, TheNetherlands and the UK) and with the participation of ISAS and NASA.Members of the Consortium on the ISOPHOT Serendipity Survey (CISS) areMPIA Heidelberg, ESA ISO SOC Villafranca, AIP Potsdam, IPAC Pasadena,Imperial College London.Full Table 4 and Table 6 are only available in electronic form at theCDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/422/39
| Revised positions for CIG galaxies
We present revised positions for the 1051 galaxies belonging to theKarachentseva Catalog of Isolated Galaxies (CIG). New positions werecalculated by applying SExtractor to the Digitized Sky Survey CIG fieldswith a spatial resolution of 1 arcsper 2. We visually checked theresults and for 118 galaxies had to recompute the assigned positions dueto complex morphologies (e.g. distorted isophotes, undefined nuclei,knotty galaxies) or the presence of bright stars. We found differencesbetween older and newer positions of up to 38 arcsec with a mean valueof 2 arcsper 96 relative to SIMBAD and up to 38 arcsec and 2 arcsper 42respectively relative to UZC. Based on star positions from the APMcatalog we determined that the DSS astrometry of five CIG fields has amean offset in (alpha , delta ) of (-0 arcsper 90, 0 arcsper 93) with adispersion of 0 arcsper 4. These results have been confirmed using the2MASS All-Sky Catalog of Point Sources. The intrinsic errors of ourmethod combined with the astrometric ones are of the order of 0 arcsper5.Full Table 1 is only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/411/391
| 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.
| 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.
| 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.
| Radio emission of isolated single and double galaxies
The catalogs of Karachentsev (1972) and Karachentseva (1973) are used tocompare the properties of isolated single and double galaxies, andquantitative results are obtained. It is shown that spiral galaxieswhich are members of pairs have a radio luminosity exceeding that ofsingle galaxies by 2.5 times on the average. In addition, it is foundthat members of interacting pairs are more powerful emitters in theradio range and that spiral galaxies which are members of triplets haveradio luminosities on a par with those of pair members.
| A 21 CM survey of the Pisces-Perseus supercluster. I - The declination zone +27.5 to +33.5 degrees
Neutral-hydrogen 21 cm line data for a sample of galaxies in the regionbounded by 22 h less than R.A. less than 04h, + 27 deg 30 arcmin Dec.less than + 33 deg 30 arcmin are presented as the first installment of asurvey of galaxies in the region of the Pisces-Perseus supercluster. Ofthe 415 galaxies observed in this strip with the Arecibo 305 mtelescope, 342 have been detached in the 21 cm line; another ten haveuseful upper limits to their H I content. The sample includes mostspiral, irregular, and dwarf galaxies larger than 1 arcmin; in selectedareas, spirals to a limiting magnitude of + 15.7 have been observed. Thevelocity distribution of the 511 galaxies with known redshift in thiszone deviates markedly from that expected for a similar sample ofrandomly placed objects. The region contains significant clustering inall three dimensions.
| Neutral hydrogen in isolated galaxies. IV - Results for the Arecibo sample
A standard sample for the comparison of the H I content of galaxies invarious intergalactic environments is presently defined by means ofobservations of 324 isolated galaxies lying in the declination rangeaccessible to the Arecibo 305-m telescope. Both mapping and single pointspectra are used to compute the integral properties of these galaxies.Neutral hydrogen was detected in 288 of the 324 galaxies surveyed, andit is noted that the optical diameter of a spiral disk is bettercorrelated with the hydrogen mass than the morphological type. When usedto define a measure of H I content, the isolated galaxy sample canpredict 'normalcy' with an accuracy that carries a standard error ofabout 0.20 in the log of the H I mass, if a dependence on disk size, aswell as type, is taken into account.
| A survey of galaxy redshifts. IV - The data
The complete list of the best available radial velocities for the 2401galaxies in the merged Zwicky-Nilson catalog brighter than 14.5mz and with b (II) above +40 deg or below -30 deg ispresented. Almost 60 percent of the redshifts are from the CfA surveyand are accurate to typically 35 km/s.
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