11. A method comprising: receiving a search query; determining, using one or more processors, that the search query matches a topic among a plurality of topics, each topic of the plurality of topics i) describing information included by a document of multiple documents and ii) distinguishing the document from the remaining documents of the multiple documents; identifying multiple identities associated with the topic based on multiple documents in which the topic is referred, each identity of the multiple identities corresponding to an expert of one or more experts; for each document of the multiple documents, obtaining a composite score of each identity of the document based on an aggregation of aggregate scores of the identity for the document, the aggregate score of each identity based on a topic score associated with the document and an identity score of each identity associated with the document, the identity score for each identity indicating a degree of relevance between the identity and the document, and the topic score for the topic indicating a degree of relevance between the topic and the document; ordering the multiple identities based on a respective composite score associated with each document of the multiple documents; and presenting the multiple identities based on the ordering.
11. A method comprising: receiving a search query; determining, using one or more processors, that the search query matches a topic among a plurality of topics, each topic of the plurality of topics i) describing information included by a document of multiple documents and ii) distinguishing the document from the remaining documents of the multiple documents; identifying multiple identities associated with the topic based on multiple documents in which the topic is referred, each identity of the multiple identities corresponding to an expert of one or more experts; for each document of the multiple documents, obtaining a composite score of each identity of the document based on an aggregation of aggregate scores of the identity for the document, the aggregate score of each identity based on a topic score associated with the document and an identity score of each identity associated with the document, the identity score for each identity indicating a degree of relevance between the identity and the document, and the topic score for the topic indicating a degree of relevance between the topic and the document; ordering the multiple identities based on a respective composite score associated with each document of the multiple documents; and presenting the multiple identities based on the ordering. 42. The method of claim 11 , wherein aggregate score of each topic for each document is a product of the topic score of the topic associated with the document and the identity score associated with the document.