Spiral Galaxies with HST/NICMOS. II. Isophotal Fits and Nuclear Cusp Slopes

Abstract

We present surface brightness profiles for 56 of the 78 spiral galaxies observed in the HST/{\tt NICMOS/Camera-2} F160W snapshot survey introduced in Carollo et al. (2001; paper I), as well as surface brightness profiles for 23 objects out of the 41 that were also observed in the F110W filter. We fit these surface brightness profiles with the Nuker law of Lauer et al. (1995), and use the smooth analytical descriptions of the data to compute the average nuclear stellar cusp slopes $<\gamma >$ in the 0.1${}^{\prime \prime }-0.5^{\prime \prime }$ radial range. Our main result is the startling similarity between the nuclear stellar cusp slopes $<\gamma >$ in the near-infared compared to those derived in the visual passband. This similarity has several implications: (1.) There are typically little or no optical-NIR {\it global} color gradients, and thus no global stellar population variations, inside $\sim 50$-100 pc from the nucleus in nearby spirals. (2.) The large observed range of the strength of the nuclear stellar cusps seen in the HST optical study of spiral galaxies reflects a physical difference between galaxies, and is not an artifact caused by nuclear dust and/or recent star formation. (3.) The dichotomy between $R^{1/4}$ bulges, with steep nuclear stellar cusps $<\gamma >\sim 1$, and exponential bulges, with shallow nuclear stellar cusps $<\gamma ><0.3$, is also not an artifact of the effects of dust or recent star formation. (4) A surrounding massive disk appears to have no effect on the rise of the stellar density distribution within the innermost hundred pc of the

Astronomical Journal, 2002, January Issue

References in corpus (1)

• Spiral Galaxies with HST/NICMOS. I. Nuclear Morphologies, Color Maps and Distinct Nuclei

Cited by in corpus (24)

• Secular Evolution and the Formation of Pseudobulges in Disk Galaxies
• Nuclear Star Clusters
• A New Empirical Model for the Structural Analysis of Early-type Galaxies and a Critical Review of the Nuker Model
• Gas Physics, Disk Fragmentation, and Bulge Formation in Young Galaxies
• Evidence for a New Elliptical-Galaxy Paradigm: Sersic and Core Galaxies
• Quantifying the Coexistence of Massive Black Holes and Dense Nuclear Star Clusters
• Galactic bulges from Hubble Space Telescope NICMOS observations: the lack of r^{1/4} bulges
• The Carnegie-Irvine Galaxy Survey. I. Overview and Atlas of Optical Images
• Spiral Galaxies with HST/NICMOS. I. Nuclear Morphologies, Color Maps and Distinct Nuclei
• Galactic Bulges from HST NICMOS Observations: central galaxian objects, and nuclear profile slopes
• Circumnuclear Gas in Seyfert 1 Galaxies: Morphology, Kinematics, and Direct Measurement of Black Hole Masses
• Late-type galaxies observed with SAURON. Two-dimensional stellar and emission-line kinematics of 18 spirals
• Old and young bulges in late-type disk galaxies
• The host galaxy/AGN connection in nearby early-type galaxies. A new view of the origin of the radio-quiet/radio-loud dichotomy?
• Nuclear properties of a sample of nearby spirals from STIS imaging
• The dynamical structure of isotropic spherical galaxies with a central black hole
• The nature of late-type spiral galaxies: structural parameters, optical and near-infrared colour profiles, and dust extinction
• The Build-Up of Nuclear Stellar Cusps in Extreme Starburst Galaxies and Major Mergers
• The Toomre Sequence Revisited with HST/NICMOS: Nuclear Brightness Profiles and Colors of Interacting and Merging Galaxies
• Nuclear Properties of Nearby Spiral Galaxies from Hubble Space Telescope NICMOS imaging and STIS Spectroscopy
• Secular Evolution and the Growth of Pseudobulges in Disk Galaxies
• Formation of bulges in very late-type galaxies from SSCs
• A triple nucleus in the Brightest Cluster Galaxy in Abell 193
• Star Formation Rate Distribution in the Galaxy NGC 1232