We explore X-ray evidence for the presence of active galactic nuclei ( AGNs ) in the two most actively star-forming Green Pea galaxies ( GPs ) , SDSS J0749+3337 and SDSS J0822+2241 , which have star-formation rates ( SFRs ) of 123 ~ { } M _ { \odot } yr ^ { -1 } and 78 ~ { } M _ { \odot } yr ^ { -1 } , respectively .
The GPs have red mid-infrared ( MIR ) spectral energy distributions and higher 22 \mu m luminosities than expected from a proxy of the SFR ( H \alpha luminosity ) , consistent with hosting AGNs with 2–10 keV luminosities of \sim 10 ^ { 44 } erg s ^ { -1 } .
We thus obtain and analyze the first hard ( > 10 keV ) X-ray data observed with NuSTAR and archival XMM-Newton data below 10 keV .
From the NuSTAR \approx 20 ksec data , however , we find no significant hard X-ray emission .
By contrast , soft X-ray emission with 0.5–8 keV luminosities of \approx 10 ^ { 42 } erg s ^ { -1 } is significantly detected in both targets , which can be explained only by star formation ( SF ) .
A possible reason for the lack of clear evidence is that a putative AGN torus absorbs most of the X-ray emission .
Applying a smooth-density AGN torus model , we determine minimum hydrogen column densities along the equatorial plane ( N _ { H } ^ { eq } ) consistent with the non-detection .
The results indicate N _ { H } ^ { eq } \gtrsim 2 \times 10 ^ { 24 } cm ^ { -2 } for SDSS J0749+3337 and N _ { H } ^ { eq } \gtrsim 5 \times 10 ^ { 24 } cm ^ { -2 } for SDSS J0822+2241 .
Therefore , the GPs may host such heavily obscured AGNs .
Otherwise , no AGN exists and the MIR emission is ascribed to SF .
Active SF in low-mass galaxies is indeed suggested to reproduce red MIR colors .
This would imply that diagnostics based on MIR photometry data alone may misidentify such galaxies as AGNs .