In this paper we investigate the stellar populations and star formation histories of 235 active galactic nucleus(AGN)-host dwarf galaxies,consisting of four samples identified separately with different methods(i.e.,ra...In this paper we investigate the stellar populations and star formation histories of 235 active galactic nucleus(AGN)-host dwarf galaxies,consisting of four samples identified separately with different methods(i.e.,radio,X-ray,mid-IR and variability),utilizing the synthesis code STARLIGHT and spectra from the Sloan Digital Sky Survey Data Release 8.Our results show that the variability sample is the oldest,while the mid-IR sample is the youngest,for which the luminosity at 4020?is dominated(>50%)by the young population(t<10~8yr).The light-weighted mean stellar age of the whole sample is in general about 0.7 dex younger than the optical sample studied in Cai et al.We compare the population results between fitting models with and without a power-law(PL)component and find that the neglect of a PL component would lead to an under-and over-estimation by 0.2 and0.1 dex for the light-and mass-weighted mean stellar age,respectively,for our sample of dwarf galaxies,which has a mean fractional contribution of~16%from the AGN.In addition,we obtain further evidence for a possible suppression of star formation in the host galaxy by the central AGN.We also find that there exists an anticorrelation between the extinction-corrected[O III]luminosity and light-weighted mean stellar age,confirming our previous finding that there is a physical connection between AGN and star-forming activities in AGN-host dwarfs.展开更多
Based on MaNGA integral field unit(IFU) spectroscopy we search 60 AGN candidates,which have stellar masses M*≤5 × 10^(9) M⊙ and show AGN ionization signatures in the BPT diagram.For these AGN candidates,we deri...Based on MaNGA integral field unit(IFU) spectroscopy we search 60 AGN candidates,which have stellar masses M*≤5 × 10^(9) M⊙ and show AGN ionization signatures in the BPT diagram.For these AGN candidates,we derive the spatially resolved stellar population with the stellar population synthesis code STARLIGHT and measure the gradients of the mean stellar age and metallicity.We find that the gradients of mean stellar age(metallicity) of individual AGN-host dwarfs are diverse in 0-0.5 Re,0.5-1 Re and 0-1 Re.However,the overall behavior of the mean stellar age(metallicity) profiles tend to be flat,as the median values of the gradients are close to zero.We further study the overall behavior of the mean stellar age(metallicity) by plotting the co-added radial profiles for the AGN sample and compare with a control sample with similar stellar mass.We find that the median values of light-weighted mean stellar ages of the AGN sample are as old as 2-3 Gyr within 2 Re,which are about 4-7 times older than those of the control sample.Meanwhile,most of the AGN candidates are low-level AGNs,as only eight sources have L[OⅢ]>1039.5 erg s^(-1).Hence,the AGNs in dwarf galaxies might accelerate the evolution of galaxies by accelerating the consumption of the gas,resulting in an overall quenching of the dwarf galaxies,and the AGNs also become weak due to the lack of gas.The median values of mass-weighted mean stellar age of both samples within 2 Re are similar and as old as about 10 Gyr,indicating that the stellar mass is mainly contributed by old stellar populations.The gradients of co-added mean stellar metallicity for both samples tend to be negative but close to zero,and the similar mean stellar metallicity profiles for both samples indicate that the chemical evolution of the host galaxy is not strongly influenced by the AGN.展开更多
基金supported by the China Manned Space Project with No.CMSCSST-2021-A06the National Key R&D Program of China with No.2021YFA1600404+7 种基金the National Natural Science Foundation of China(NSFCgrant Nos.12173079 and 11991051)The STARLIGHT project is supported by the Brazilian agencies CNPqCAPESand FAPESP and by the France-Brazil CAPES/Cofecub programFunding for SDSS-III has been provided by the Alfred P.Sloan Foundationthe National Science Foundationthe U.S.Department of Energy Office of Science。
文摘In this paper we investigate the stellar populations and star formation histories of 235 active galactic nucleus(AGN)-host dwarf galaxies,consisting of four samples identified separately with different methods(i.e.,radio,X-ray,mid-IR and variability),utilizing the synthesis code STARLIGHT and spectra from the Sloan Digital Sky Survey Data Release 8.Our results show that the variability sample is the oldest,while the mid-IR sample is the youngest,for which the luminosity at 4020?is dominated(>50%)by the young population(t<10~8yr).The light-weighted mean stellar age of the whole sample is in general about 0.7 dex younger than the optical sample studied in Cai et al.We compare the population results between fitting models with and without a power-law(PL)component and find that the neglect of a PL component would lead to an under-and over-estimation by 0.2 and0.1 dex for the light-and mass-weighted mean stellar age,respectively,for our sample of dwarf galaxies,which has a mean fractional contribution of~16%from the AGN.In addition,we obtain further evidence for a possible suppression of star formation in the host galaxy by the central AGN.We also find that there exists an anticorrelation between the extinction-corrected[O III]luminosity and light-weighted mean stellar age,confirming our previous finding that there is a physical connection between AGN and star-forming activities in AGN-host dwarfs.
基金supported by the National Key R&D Program of China (Grant No.2017YFA0402704)the National Natural Science Foundation of China (NSFC+3 种基金Grant Nos.11991051,11421303 and 11973039)the CAS Pioneer Hundred Talents Programsupported by the Brazilian agencies CNPq,CAPES,and FAPESPby the France-Brazil CAPES/Cofecub program。
文摘Based on MaNGA integral field unit(IFU) spectroscopy we search 60 AGN candidates,which have stellar masses M*≤5 × 10^(9) M⊙ and show AGN ionization signatures in the BPT diagram.For these AGN candidates,we derive the spatially resolved stellar population with the stellar population synthesis code STARLIGHT and measure the gradients of the mean stellar age and metallicity.We find that the gradients of mean stellar age(metallicity) of individual AGN-host dwarfs are diverse in 0-0.5 Re,0.5-1 Re and 0-1 Re.However,the overall behavior of the mean stellar age(metallicity) profiles tend to be flat,as the median values of the gradients are close to zero.We further study the overall behavior of the mean stellar age(metallicity) by plotting the co-added radial profiles for the AGN sample and compare with a control sample with similar stellar mass.We find that the median values of light-weighted mean stellar ages of the AGN sample are as old as 2-3 Gyr within 2 Re,which are about 4-7 times older than those of the control sample.Meanwhile,most of the AGN candidates are low-level AGNs,as only eight sources have L[OⅢ]>1039.5 erg s^(-1).Hence,the AGNs in dwarf galaxies might accelerate the evolution of galaxies by accelerating the consumption of the gas,resulting in an overall quenching of the dwarf galaxies,and the AGNs also become weak due to the lack of gas.The median values of mass-weighted mean stellar age of both samples within 2 Re are similar and as old as about 10 Gyr,indicating that the stellar mass is mainly contributed by old stellar populations.The gradients of co-added mean stellar metallicity for both samples tend to be negative but close to zero,and the similar mean stellar metallicity profiles for both samples indicate that the chemical evolution of the host galaxy is not strongly influenced by the AGN.
