We present the detection of supermassive black holes ( BHs ) in two Virgo ultracompact dwarf galaxies ( UCDs ) , VUCD3 and M59cO .
We use adaptive optics assisted data from the Gemini/NIFS instrument to derive radial velocity dispersion profiles for both objects .
Mass models for the two UCDs are created using multi-band Hubble Space Telescope ( HST ) imaging , including the modeling of mild color gradients seen in both objects .
We then find a best-fit stellar mass-to-light ratio ( M / L ) and BH mass by combining the kinematic data and the deprojected stellar mass profile using Jeans Anisotropic Models ( JAM ) .
Assuming axisymmetric isotropic Jeans models , we detect BHs in both objects with masses of 4.4 ^ { +2.5 } _ { -3.0 } \times 10 ^ { 6 } M _ { \odot } in VUCD3 and 5.8 ^ { +2.5 } _ { -2.8 } \times 10 ^ { 6 } M _ { \odot } in M59cO ( 3 \sigma uncertainties ) .
The BH mass is degenerate with the anisotropy parameter , \beta _ { z } ; for the data to be consistent with no BH requires \beta _ { z } = 0.4 and \beta _ { z } = 0.6 for VUCD3 and M59cO , respectively .
Comparing these values with nuclear star clusters shows that while it is possible that these UCDs are highly radially anisotropic , it seems unlikely .
These detections constitute the second and third UCDs known to host supermassive BHs .
They both have a high fraction of their total mass in their BH ; \sim 13 % for VUCD3 and \sim 18 % for M59cO .
They also have low best-fit stellar M / L s , supporting the proposed scenario that most massive UCDs host high mass fraction BHs .
The properties of the BHs and UCDs are consistent with both objects being the tidally stripped remnants of \sim 10 ^ { 9 } M _ { \odot } galaxies .