摘要
We searched the Chandra and XMM archives for observations of 900 green pea galaxies to find AGN signatures. Green peas are low-mass galaxies with prominent emission lines, similar in size and star formation rate to high-redshift dwarf galaxies. Of the 29 observations found, 9 show X-ray detections with$S/N>3$ . The 2-10 keV X-ray luminosity for these 9 sources exceeds$10^{40}~\mathrm{erg~s}^{-1}$ , with 2 sources exceeding$10^{41}~\mathrm{erg~s}^{-1}$ , suggesting the presence of intermediate-mass black holes (IMBH) or low-luminosity AGN (LLAGN) with BH masses between$100-10^6M_\mathrm{\odot}$ . All X-ray detected sources (plus 6 additional sources) show He~II $\lambda4686$emission and a broad component of the H $\alpha$emission line, indicating winds. The line widths of the broad H $\alpha$and He II $\lambda4686$emitting gas clouds are weakly correlated ( $R^{2}=0.15$ ), suggesting He II $\lambda4686$emission is inconsistent with winds from super-Eddington accretors. However, the ratio of X-ray luminosity to star formation rate shows an anti-correlation with metallicity in 5 out of 9 X-ray detected sources, implying ultraluminous X-ray sources are key contributors to the observed X-ray luminosity. This could be due to super-Eddington accretors or IMBH. The X-ray emission is much higher than that produced by Wolf-Rayet stars and supernovae-driven winds. Thus, the X-ray luminosity in these 9 sources can only be explained by black holes with masses over$100~M_\mathrm{\odot}$ . Our findings suggest the presence of LLAGN in these galaxies, with broad H $\alpha$line widths implying BH masses of$10^4-10^6M_\mathrm{\odot}$ . Given Green Peas' role as significant Lyman Continuum leakers, LLAGN in these galaxies could have contributed significantly to cosmic reionization.