The simplest way to answer your question to me is: if a Central Bank can for example raise the interest rate then the prices of assets such as bonds and stocks will decrease to equalize theirs returns with the new interest rate. If in this simplest model the price of a stock is its dividend divided by the interest rate and the Central Bank is able to raise the interest rate then in this very simple model the price of the stock will fall. If interest goes up the demand for the existing standards bonds and stock goes down and their prices goes down to equalize its returns with the higher rate of interest. All this in the simplest model. If the Central Bank lowers the interest rate the contrary would be true, thinking only in this limited framework.

In equilibrium can not be different assets with different return adjusted by risk. If these returns for term deposits, bonds, and stock were in equilibrium before the change in interest rate after the change in interest its returns will change to adjust to the new situation. For existing standard bonds and stocks their returns in the market must change with the change in interest rate and for that it is nedeed that their prices change. The market will react when the information arrives to it, in absence of insider information. Is the market is efficient in weak and semistrong form all new public information will affect the prices of the assets in the market including the interest rate.If the new is expected the market react with the expectation. If the new is unexpected the market react when the new arrives. The timing of the adjustment of the prices of the assets to change in the interest rate will be different but the adjustment will take place being the news expected or unexepected

Yes, Central Banks can affect asset prices by ' the open market operations , the foreign exchange market intervention , and by the direct asset purchases as has been done in the USA by the Federal Reserve System recently .In open market operations , when the central banks buy or sell the securities their prices are affected.The foreign exchange market intervention is often done to influences the exchange rates. The Federal Reserve system purchased the ' mortgage bonds ' to raise its prices in the market .When the central banks increase the money supply, if that will lead to the market value of assets relative to the replacement cost of capital and assets , and therefore , will lead to more investments in the economy , is a topic studied under the ' transmission mechanism of monetary policy '.

https://papers.ssrn.com/sol3/papers.cfm?abstract_id=2629978

https://www4.troweprice.com/iws/wps/wcm/connect/a1d431004a7c260f933cf30dd808399c/Global_Monetary_Stimulus_US_Final.pdf?MOD=AJPERES&extPDF=true&src=IB_FIHPSlider

https://books.google.com.tr/books?id=56jlY1XU6dMC&pg=PA299&lpg=PA299&dq=central+bank+actions+affect+asset+prices&source=bl&ots=kG3rTki2nY&sig=U9uiGAUTi_fN1cwufs9wNc8xjf0&hl=tr&sa=X&ved=0ahUKEwjn892Lv-PYAhXMOSwKHdqrBw8Q6AEIYDAH#v=onepage&q=central%20bank%20actions%20affect%20asset%20prices&f=false