Arnau Ramon was the Count of Pallars Jussà from 1098 until his death. He was the second son of Ramon IV

Raymond IV of Pallars Jussà

Raymond IV was the Count of Pallars Jussà from 1047 until his death in 1098. He was the son and successor of Raymond III and Ermessenda. His reign was characterised by ceaseless wars and litigations with his cousins Artau I and Artau II of Pallars Sobirà, yet it was transformative in the history...

 and co-ruled with his elder brother Pere Ramon until the latter's death in 1111. After this he was succeeded by his younger brother Bernat Ramon. There is preserved a document recording how Ramon IV exempted Arnau from owing his brother Pere potestas for the castle of Talarn

Talarn

Talarn is a municipality in the comarca of the Pallars Jussà in Catalonia, Spain. It is situated in the centre of the Tremp basin, on the Noguera Pallaresa river below the Sant Antoni reservoir. It is the site of a hydroelectric power station and of a training school of the Spanish army...

:

Et mandavit Raimundus comes que non donasset potestatem Arnallus iamdictus de ipso castro de Talarn a Petro comite, si non erat bauzia conprobata.

And Count Ramon ordered that the aforementioned Arnau should not give potestas for that castle of Talarn, unless he was proved a traitor.

The right of potestas ("power") was the right of a superior to assume direct control of a castle upon request.