Ghost Families in the Inner Asteroid Belt

In the inner asteroid belt, the mean size of the high-inclination (I > 9 degrees), non-family asteroids increases with increasing orbital inclination. This observation can be accounted for by the loss of small asteroids from the escape hatches at the secular resonance and the 3:1 Jovian mean motion resonance. Modeling allows us to use the observed asteroid size-orbital inclination correlation to determine the rate of loss of asteroids from the inner belt due Yarkovsky radiation forces. However, this modeling requires some knowledge of the initial distribution of the asteroids in orbital element space. Current models assume a uniform distribution of asteroids with a size-frequency distribution that was initially independent of the location of the asteroids in semimajor axis and proper inclination space. However, if the high-inclination, non-family asteroids are remnants of old ghost families, then these uniform distribution models need some modification. Here, we seek evidence for the existence of old ghost families by analyzing the distributions of the proper eccentricities and inclinations, the SFDs, and the SDSS colors and WISE albedos of the high-inclination, inner belt asteroids.