Study On The Main Sequence Relationship Of Star Forming Galaxies In COSMOS

The close relationship between star forming rate and stellar mass is called the main sequence relationship of star forming galaxies.Accurate determination;The slope,zero-point and scatter of the main sequence relationship are studied;Some analysis of these data;We can infer the physical process of galaxy formation and evolution and have certain constraints on observation.By studying the main sequence relationship of galaxies in different redshift ranges,we can determine the evolution trend of galaxy formation and evolution with redshift.In this paper,the R-band catalog data in COSMOS sky area are corrected,calculated and statistically analyzed.COSMOS survey is an astronomical survey for exploring the formation and evolution of galaxies.It is the first survey covering a large enough area with a coverage of 2 square degrees.The R-band catalog covers 30 observational data from u to mips24,including 18 wide-band photometry and 12medium band photometry,with 773712 observational data.There is a large amount of data in this table,which provides a solid guarantee for the study of the main sequence relationship of galaxies.Based on the photometric data,we calculate the photometric redshift,star formation rate and stellar massThe first part of this paper is the background.In this chapter,we give a brief introduction to the main order relationship of galaxies,including the structure of the universe,the evolution of galaxies and the background of Galaxy classification.At the end of this chapter,we will summarize the previous studies on the main sequence relationship of star forming galaxies.The second part is data processing.In this part,the photometric data used in this paper are introduced in detail,and some necessary corrections and processing are made to the photometric data.In this paper,EAZY software is used to calculate the photometric redshift.The stellar mass is calculated by FAST software,and the calculation methods of different star formation rates are introduced.The third part,the establishment of samples and the establishment of the main sequence relationship.In this chapter,the comparison,discussion and selection of two methods for calculating star formation rate are given.After the correction and calculation of the photometric data,the star forming galaxies with redshift between 0 and 2 and stellar mass above 10~9 M_?are selected,and the samples for studying the main sequence relationship of star forming galaxies are established.Based on this sample,the main sequence relationships of star forming galaxies in different redshift ranges are fitted,and the slope,zero-point and scatter of the main sequence relationships in different redshift ranges are analyzed.In this paper,with the increasing of redshift,the slope tends to be gentle.For scatter,star forming galaxies are almost constant since Z?1,while for zero-point at different redshifts,they are gradually increasing with the increase of redshift.The overall change trend of main sequence is similar to previous work.In the fourth part,we compare and discuss the work of this paper with the previous work,and further discuss the slope,zero-point and scatter of the main sequence relationship at different redshifts.In the last chapter,a brief summary of the significance of this study,research process and the final conclusion.With the continuous updating of astronomical equipment and the continuous improvement of research algorithm,the research on the main sequence relationship will be more perfect and comprehensive in the future.