MEXICO CITY — When Carmen Aristegui, Mexico’s most famous radio personality, was abruptly fired this month, nobody expected her to go quietly. But anger over her dismissal has been rising steadily, and it has turned up the heat in this country’s charged political atmosphere.

Conspiracy theories have abounded since a dispute between Ms. Aristegui and her employer, MVS Communications, ended in her departure. She has become an emblem of press freedom under siege, and social media has lighted up with demands for her return to the airwaves.

Even her critics, who point to a lack of reportorial rigor in many of her stories, argue that her dismissal removed one of the few broadcast journalists in Mexico who openly challenge authority. Many journalists contend that Ms. Aristegui’s case is part of a broader attempt by the government to check aggressive news coverage.

“Today we have radio that is less plural than it was two weeks ago,” said Raúl Trejo, a media expert at the National Autonomous University of Mexico. “I have been very critical. But I think her voice is very healthy for Mexican society.”