Dust Attenuation And Metallicity For Star-Forming Galaxies In MaNGA Survey

This thesis aims to improve our understanding of the evolution of star-forming galaxies in the local universe with the main goal of providing a complete picture of the formation and evolution of these galaxies throughout the history of the Universe.Using the MaNGA survey,we utilize a large sample of spatially resolved star-forming galaxies,and we derived the shape of the dust attenuation curve,the relation between local metallicity,stellar mass surface density,and star formation rate surface density.The first part of the thesis talked about the importance of dust attenuation curve in the local universe.Dust attenuation curve plays a crucial role for the understanding of dust evolution and to the interpretation of the stellar population in galaxies.The attenuation curve is regulated by the distribution of grain size and chemical dust composition,which plays a role in controlling the physical process of galaxy evolution.Although the research of attenuation curves of the galaxy has made a lot of improvements,but there are still many open issues regarding their shape for star-forming galaxies.For example,do any trends exist between curve properties and the physical and geometric properties of the galaxy,for example,size,star formation rate,EW(H?),stellar mass,and axial ratio(inclination)?How different are attenuation curves of from galaxy to galaxy for local and global properties?We compile a sample of about 157,000 spaxels from the MaNGA survey to derive the average dust attenuation curve for subgalactic H ? regions of local star-forming galaxies(SFGs)in the optical wavelength.We obtain a Dn(4000)-independent average attenuation curve for spaxels with 1.1 ?Dn(4000)<1.3,which is similar to the one derived from either local starbursts or normal SFGs.We examine whether and how the shape of the average attenuation curve changes with several local and global physical properties.For spaxels 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 spaxels with younger stellar population(1.1 ? Dn(4000)<1.2),shallower average attenuation curves are found for H ?regions with smaller stellar mass surface density,smaller star formation rate surface density,or those resided in either the outer region of galaxies or more massive galaxies.These results emphasize the risk of using one single attenuation law to correct the dust reddening for all type of H? regions,especially for those with fairly young stellar population.The second half of this thesis is about the relation of the local stellar mass surface density-metallicity(MZR)and fundamental metallicity relation(FMR).The gas-phase oxygen abundance of a galaxy is set by the interplay between star formation and gas flows.Previous studies show the tight correlation between global stellar mass and metallicity.This relation is known as the relation of mass-metallicity.However,there are still several studies debated questions in the local universe.Does the global fundamental metallicity relation drive the local one or different?Why the star formation rate and metallicity relation show different scenarios for lower mass or higher mass?Do the massive galaxies show similar MZR with smaller mass galaxies?The existence of SFR on FMR?We study the relations between gas-phase metallicity(Z),local stellar mass surface density(?*),and the local star formation surface density(?SFR)in a sample of 1120 star-forming galaxies from the MaNGA survey.At fixed ?*,the local metallicity increases as decreasing of ?SFR or vice versa for metallicity calibrators of N2 and O3N2.Alternatively,at fixed ?SFR metallicity increases as increasing of ?*,but at the high mass region,the trend is flatter.However,the dependence of metallicity on ?SFR is nearly disappeared for N2O2 and N2S2 calibrators.We investigate the local metallicity against ?SFR with different metallicity calibrators and find negative/positive correlations depending on the choice of the calibrator.We demonstrate that the O32 ratio(or ionization parameter)is dependent on star formation rate at fixed local stellar mass surface density,but that the trend is opposite for low and high stellar surface mass density regions.Additional,the shape of ?*-Z-?SFR(FMR)depends on metallicity calibrator and stellar mass range.We conclude that the selection of metallicity calibration affects the existence of FMR on ?SFR.