The z = 4.591 quasar PC 1415+3408 exhibits very strong associated metal–line absorption from the N v \lambda \lambda 1238 , 1242 , Si iv \lambda \lambda 1393 , 1402 , and C iv \lambda \lambda 1548 , 1550 doublets spanning the velocity interval -1700 \leq v \leq 0 km s ^ { -1 } .
Also present , are detached absorption troughs in N v and C iv spanning -5000 \leq v \leq - 3000 km s ^ { -1 } ; this is characteristic of broad absorption line ( BAL ) quasars , but the small overall velocity spread suggests that PC 1415+3408 be classified as a “ Mini–BAL ” quasar .
The N v doublet is consistent with black saturation over the velocity interval -1200 to -500 km s ^ { -1 } ; black N v absorption is extraordinary in all classes of quasars at all redshifts .
Over this velocity interval , the C iv doublet is severely blended , but also consistent with black saturation .
The material over this range of velocity appears to fully occult the continuum source , the broad emission line region , and any material that could give rise to scattered light .
In view of a unified scenario for BAL and Mini–BAL absorption , these facts imply that the quasar is being viewed along a preferred direction .
On the other hand , the black Mini–BALs in PC 1415+3408 could be explained if the BAL flow has an unusual geometry compared to the population of BAL quasars , and/or the spatial extent of a scattering region is small at the lower velocities ( -1700 \leq v \leq 0 km s ^ { -1 } ) .