Dust Attenuation And Infrared Re-Emission In Star-Forming Galaxies

Dust in the interstellar medium has significant effects on galaxy evolution and observational properties of galaxies.Under the topic of dust attenuation and infrared re-emission in star-forming galaxies,this dissertation introduces two works focused on the dust attenuation(the derivation of average dust attenuation curves for star-forming regions in local galaxies and study of the stellar-to-nebular dust attenuation ratio)and two works focused on the infrared dust re-emission(study of monochromatic extrap-olated total infrared luminosities of galaxies and relation between ages of star clusters and the surrounding mid-infrared emission)in order to improve our understanding of the related dust effects.First,based on the MaNGA data from the SDSS DR14,we derived the average dust attenuation curve for star-forming regions of local galaxies and examined whether and how the shape of the average attenuation curve changes with several local and global physical properties.For regions with 1.2 ? Dn(4000)<1.3,we find no dependence on either local or global physical properties for the shape of the average attenuation curve.However,for regions with younger stellar populations(1.1 ?Dn(4000)<1.2),shallower average attenuation curves are found for star-forming regions with smaller stellar mass surface density,smaller star formation rate surface density,or those residing in the outer region of galaxies.These results emphasize the risk of using one single attenuation curve to describe the dust reddening for all types of star-forming regions,especially for those with fairly young stellar populations.Second,utilizing the MaNGA data from the SDSS DR15,we investigated how the stellar-to-nebular dust attenuation ratio(AV,star/AV,gas)depends on other physical properties from subgalactic to galactic scales.On a subgalactic scale,we reported a stronger correlation between AV,star and AV,gas for more active H ? regions.The diffuse ionized gas regions tend to have a larger AV,star/AV,gas compared to star-forming regions excited by young OB stars.Metal-poor regions with a higher ionized level suffer much less nebular attenuation and thus have a larger AV,star/AV,gas ratio.Based on these obser-vations,we suggest that both the geometry of stars/dust and the local physical conditions play an important role in determining AV,star/AV,gas.The AV,star/AV,gas within individ-ual star-forming galaxies converge to a constant,which varies from galaxy to galaxy and depends on several galactic physical properties,such as stellar mass,star formation rate,and metallicity.The dust growth process in the interstellar medium accompanied by galaxy growth might be one plausible explanation for our observations.Third,we used multi-wavelength data in GOODS-North and GOODS-South fields to investigate the accuracy of the monochromatic extrapolated total infrared luminosi-ties(LIR)based on three infrared spectral energy distribution templates(CE01,DH02,and W08)out to z?3.5.We find that the CE01 template provides the best esti-mate of LIR in Herschel/PACS bands,while the DH02 template performs best in Her-schel/SPIRE bands.We suggest that extrapolations from the available longest wave-length PACS band based on the CE01 template can be a good estimator of LIR.Finally,using the star cluster catalogs from the LEGUS,we investigated how the mass-normalized 8 ?m dust luminosity(vLv,8/M*)correlates with the mass-weighted stellar age(ageM*)on the 30-50 pc scale of star forming regions.We found a tight anticorrelation with between age M*and vLv,8/M*,i.e.,the 8 ?m luminosity decreases with increasing age of the stellar population.Simple assumptions on a combination of stellar and dust emission models reproduce the observed trend,while varying polycyclic aromatic hydrocarbon abundance(PAH)and/or fraction of stellar light absorbed by dust in the model is able to explain all of the observed scatters.We also find that the trend is better explained by continuous star formation,rather than instantaneous burst models.We ascribe this result to the presence of multiple star clusters with different ages in many of the regions.Upper limits of the dust-only 8 ?m emission as a function of age are provided.