java, throwing unchecked exception by making an object of Throwable

Question

what is the difference between the following two codes? one of them is working fine while other is giving a compilation error.

compilation problem in code 1

class XYZ
{
    public static void main(String[] args) 
    {
        Throwable obj = new ArithmeticException("this is an error");    
        throw obj;
    }
}

ERROR -

XYZ.java:7: error: unreported exception Throwable; must be caught or declared to be thrown
                throw obj;
                ^
1 error
error: compilation failed

Successful execution in code 2

class XYZ
{
    public static void main(String[] args) //throws InterruptedException
    {
        throw new ArithmeticException("this is an error");
    }
}

output

Exception in thread "main" java.lang.ArithmeticException: this is an error
        at XYZ.main(XYZ.java:6)

As we can see both the codes are identical but the one at the top is giving a compilation error whereas the second code is working without a flaw.

I wanna know

• why this is so?

• How can I make my first code work fine?