According to the Wall Street Journal, in order to attempt to slow the economic contraction caused by the Covid-19 virus, the Federal Reserve has promised to inject $1.5 trillion into the economy, by
[making] vast sums of short-term loans available on Wall Street and [purchasing] Treasury securities in a coronavirus-related response aimed at preventing ominous trading conditions from creating a sharper economic contraction.
How can such a large sum of money be allocated to this without any debate or official order by the government? Where does this money come from? And how does providing loans to Wall Street help prevent the economy from contracting further?