you observe in the figure mentioned above that the gap between the spread on Baa bonds and on Aaa bonds went up too much (compared to other periods) during the period of financial crisis of 2008. what could be the possible reason for that? give me the logic and dynamics of how it happened. I need one page answer plz

Chapter 3 Valuing Bonds FIGURE 3.9 Yield spreads between corporate and 10-yea Treasury bonds. Spread on Baa bonds Yield spread between corporate and government bonds, % WAV wim "MVL Spread on Aaa bonds Apr. 1953 Mar. 1956 Feb. 1959 Jan. 1962 Dec. 1964 Nov. 1967 Oct. 19701 July 2014 Oct. 2005 Sept. 2008 Aug. 2011 Nov. 2002 Dec. 1999 Feb. 1994 Jan. 1997 Apr. 1988 Mar. 1991 June. 1982 July. 1979 May. 1985 Sep. 1973 Aug. 1976 Because of the risk of default, yields on corporate bonds are higher than those of govern- ment bonds. For example, Figure 3.9 shows the yield spread of corporate bonds against U.S. Treasuries. Notice that the spreads widen as safety falls off. Notice also how spreads vary over time. They widened dramatically, for example, during the credit crunch of 2007 to 2009.16