J/ApJ/789/76ivo://CDS.VizieR/J/ApJ/789/76doi:10.26093/cds/vizier.17890076CDSMao Y.-W.Kong X.Lin L.2017-05-09T07:40:00Z2017-03-13T13:00:45ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frgalaxiesphotometryinterstellar-mediuminfrared-photometryultraviolet-photometryVariations in the attenuation law have a significant impact on observed spectral energy distributions for galaxies. As one important observational property for galaxies at ultraviolet and infrared wavelength bands, the correlation between infrared-to-ultraviolet luminosity ratio and ultraviolet color index (or ultraviolet spectral slope), i.e., the IRX-UV relation (or IRX-{beta} relation), offered a widely used formula for correcting dust attenuation in galaxies, but the usability appears to be in doubt now because of considerable dispersion in this relation found by many studies. In this paper, on the basis of spectral synthesis modeling and spatially resolved measurements of four nearby spiral galaxies, we provide an interpretation of the deviation in the IRX-UV relation with variations in the attenuation law. From both theoretical and observational viewpoints, two components in the attenuation curve, the linear background and the 2175 {AA} bump, are suggested to be the parameters in addition to the stellar population age (addressed in the first paper of this series) in the IRX-UV function; different features in the attenuation curve are diagnosed for the galaxies in our sample. Nevertheless, it is often difficult to ascertain the attenuation law for galaxies in actual observations. Possible reasons for preventing the successful detection of the parameters in the attenuation curve are also discussed in this paper, including the degeneracy of the linear background and the 2175 {AA} bump in observational channels, the requirement for young and dust-rich systems to study, and the difficulty in accurate estimates of dust attenuations at different wavelength bands.2014ApJ...789...76Mhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/789/76CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/AJ/121/3048 : Multicolor photometry in NGC 1512 and NGC 5248 (Maoz+, 2001)J/ApJS/143/377 : UV-to-FIR magnitudes for 83 starburst galaxies (Wu+, 2002)J/ApJ/586/794 : Multiwavelength luminosities of galaxies (Bell, 2003)J/ApJS/173/185 : GALEX ultraviolet atlas of nearby galaxies (Gil de Paz+, 2007)J/ApJ/757/52 : UV and IR observations for SINGS galaxies. I. (Mao+, 2012)J/ApJS/199/22 : UV to far-IR photometry of galaxiesJ/ApJ/783/135 : UV to IR fluxes of 221 early-type galaxies (Amblard+, 2014)J/A+A/581/A33 : Nearby radio galaxies FUV to MIR properties (De Ruiter+, 2015)J/AJ/150/31 : Photometry and redshifts of galaxies in the UDFhttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/789/76https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/789/76http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/789/76https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/789/76https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/789/76http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/789/76GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/789/76/table3 (Aperture Photometry of the UV Clusters)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/789/76/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/789/76/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/789/76/table3?GETtext/xml+votable180.050000true148.85369.2190.005555555555555556Cone search capability for table J/ApJ/789/76/table4 (Aperture Photometry of the IR Clusters)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/789/76/table4?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/789/76/table4?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/789/76/table4?GETtext/xml+votable180.050000true148.74969.2370.0055555555555555566/7606 11026 11027 13522 26271https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/789/76?format=asciiOpticalInfraredUVdefaultJ/ApJ/789/76/table3Aperture Photometry of the UV ClustersIDIdentifier (1)meta.id;meta.maincharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRAJ2000Aperture Right Ascension (J2000)degpos.eq.ra;meta.mainDEJ2000Aperture Declination (J2000)degpos.eq.dec;meta.mainLFUVGALEX/FUV band luminosity; erg/s (2)1e-07Wphys.luminosity;em.UVdoublee_LFUVUncertainty in LFUV1e-07Wstat.errordoubleLNUVGALEX/NUV band luminosity; erg/s (2)1e-07Wphys.luminosity;em.UVdoublee_LNUVUncertainty in LNUV1e-07Wstat.errordoubleLHaThe H{alpha} luminosity; erg/s (3)1e-07Wphys.luminosity;em.line.Halphadoublee_LHaUncertainty in LHa1e-07Wstat.errordoubleL8Spitzer/IRAC 8 micron band dust luminosity; erg/s (3)1e-07Wphys.luminosity;em.IRdoublee_L8Uncertainty in L81e-07Wstat.errordoubleL24Spitzer/MIPS 24 micron band luminosity; erg/s (3)1e-07Wphys.luminosity;em.IR.15-30umdoublee_L24Uncertainty in L241e-07Wstat.errordoubleJ/ApJ/789/76/table4Aperture Photometry of the IR ClustersIDIdentifier (1)meta.id;meta.maincharRAJ2000Aperture Right Ascension (J2000)degpos.eq.ra;meta.mainrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintDEJ2000Aperture Declination (J2000)degpos.eq.dec;meta.mainLFUVGALEX/FUV band luminosity; erg/s (2)1e-07Wphys.luminosity;em.UVdoublee_LFUVUncertainty in LFUV1e-07Wstat.errordoubleLNUVGALEX/NUV band luminosity; erg/s (2)1e-07Wphys.luminosity;em.UVdoublee_LNUVUncertainty in LNUV1e-07Wstat.errordoubleLHaThe H{alpha} luminosity; erg/s (3)1e-07Wphys.luminosity;em.line.Halphadoublee_LHaUncertainty in LHa1e-07Wstat.errordoubleL8Spitzer/IRAC 8 micron band dust luminosity; erg/s (3)1e-07Wphys.luminosity;em.IRdoublee_L8Uncertainty in L81e-07Wstat.errordoubleL24Spitzer/MIPS 24 micron band luminosity; erg/s (3)1e-07Wphys.luminosity;em.IR.15-30umdoublee_L24Uncertainty in L241e-07Wstat.errordouble