  Dark matter has been a long-standing and important issue in physics, but
direct evidence of its existence is lacking. This work aims to elucidate the
mystery and show that the dark matter hypothesis is unnecessary. We can nicely
reproduce the observed rotation curves using only conventional Newtonian
dynamics based on experimental surface brightness profiles of several galaxies.
Our success is based on realizing that the mass radial distribution follows a
stretched exponential decay with a small exponent over a few hundred
kiloparsecs. Our quantitative analysis indicates that for these four example
galaxies, there is no need to invoke the hypothetical dark matter presently
unknown to humans or the modified Newtonian dynamics (MOND) paradigm.
