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Einstein-Maxwell dilaton-axion (EMDA) gravity provides a simple framework toinvestigate the signatures of string theory. The axion and the dilaton fieldsarising in EMDA gravity have important implications in inflationary cosmologyand in addressing the late time acceleration of the universe. It is thereforeinstructive to explore the implications of such a model in explaining theastrophysical observations. In this work we explore the role of EMDA gravity inexplaining the observed shadows of black holes (M87* and Sgr A*) released bythe Event Horizon Telescope (EHT) collaboration. The Kerr-Sen metric representsthe exact, stationary and axisymmetric black hole solution of EMDA gravity.Such a black hole is characterized by the angular momentum $a$ acquired fromthe axionic field and the dilatonic charge $r_2$ arising from stringcompactifications. We study the role of spin and the dilaton charge inmodifying the shape and size of the black hole shadow. We note that black holeswith larger dilaton charge cast a smaller shadow. We investigate theconsequences of such a result in addressing the EHT observations of M87* andSgr A*. Our analysis reveals that the shadow of M87* exhibits a preferencetowards the Kerr scenario. However, when 10% offset in the shadow diameter isconsidered, $0.1\lesssim r_2\lesssim 0.3$ is observationally favored within1-$\sigma$. The shadow of Sgr A* on the other hand shows a preference towardsthe Kerr-Sen scenario since the central value of its shadow can be betterexplained by a non-zero dilaton charge $0.1 \lesssim r_2 \lesssim 0.4$.However, when the 1-$\sigma$ interval is considered the Kerr scenario isincluded. We discuss the implications of our results.

Imprints of Einstein-Maxwell dilaton-axion gravity in the observed shadows of Sgr A* and M87*