The Upper Asymptotic Giant Branch of the Elliptical Galaxy Maffei 1 and Comparisons with M32 and NGC 5128

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Abstract
Deep near-infrared images obtained with adaptive optics systems on the Gemini North and Canada-France-Hawaii telescopes are used to investigate the bright stellar content and central regions of the nearby elliptical galaxy Maffei 1. Stars evolving on the upper asymptotic giant branch (AGB) are resolved in a field 3 arcmin from the center of the galaxy. The locus of bright giants on the (K, H-K) color-magnitude diagram is consistent with a population of stars like those in Baade's Window reddened by E(H-K) = 0.28 +/- 0.05 mag. This corresponds to A_V = 4.5 +/- 0.8 mag, and is consistent with previous estimates of the line of sight extinction computed from the integrated properties of Maffei 1. The AGB-tip occurs at K = 20.0, which correponds to M_K = -8.7; hence, the AGB-tip brightness in Maffei 1 is comparable to that in M32, NGC 5128, and the bulges of M31 and the Milky-Way. The near-infrared luminosity functions (LFs) of bright AGB stars in Maffei 1, M32, and NGC 5128 are also in excellent agreement, both in terms of overall shape and the relative density of infrared-bright stars with respect to the fainter stars that dominate the light at visible and red wavelengths. It is concluded that the brightest AGB stars in Maffei 1, NGC 5128, M32, and the bulge of M31 trace an old, metal-rich population, rather than an intermediate age population. It is also demonstrated that Maffei 1 contains a distinct red nucleus, and this is likely the optical signature of low-level nuclear activity and/or a distinct central stellar population. Finally, there is an absence of globular clusters brighter than the peak of the globular cluster LF in the central 700 x 700 parsecs of Maffei 1.
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