As academic researchers become experts in one or more fields, they have often specialized in writing about subjects within their expertise, often earning prestige as sources of reliable information and perspectives on these topics.
One source of expert authors on various subject matters is the Scholars Strategy Network. Here's how they determine experts, as described by their About page:
"The Scholars Strategy Network (SSN) is a national membership organization made up of college- and university-based researchers interested in improving policy and strengthening democracy. Founded in 2011 by Theda Skocpol, Victor S. Thomas Professor of Government and Sociology at Harvard University, SSN has grown into a network of over 1800 researchers in 47 states. SSN members organize themselves into local chapters across the United States, working to advance the use of research wherever policy decisions are made - from city halls to state legislatures to Washington."
Professor of Sociology and Director of the Immigrant Well-Being Research Center, University of South Florida-Tampa
Professor of Sociology and Director, Center for Latin American and Latino Studies, American University
Assistant Professor / Lecturer Critical Human Geography, University of Leeds
Associate Professor of Labor Relations, Law & History, School of Industrial and Labor Relations, Cornell University
Associate Professor of Women's, Gender, and Sexuality Studies, Stony Brook University
Associate Professor in Urban & Region Planning and Ethnic & Women’s Studies, California State Polytechnic University, Pomona
Herbert Kurz Chair of Constitutional Rights and Associate Professor of Political Science, CUNY Brooklyn College
Director of Research, Latino Policy Forum
Professor of Geography and Geosciences, University of Louisville
Associate Professor of Political Science, University of California, San Diego