Tim Heckman

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We present an analysis of the host properties of 85224 emission-line galaxies selected from the Sloan Digital Sky Survey. We show that Seyferts and LINERs form clearly separated branches on the standard optical diagnostic diagrams. We derive a new empirical classification scheme which cleanly separates star-forming galaxies, composite AGN-H ii galaxies,(More)
We investigate trends between the recent star formation history and black hole growth in galaxy bulges in the Sloan Digital Sky Survey (SDSS). The galaxies lie at 0.01 < z < 0.07 where the fibre aperture covers only the central 0.6-4.0 kpc diameter of the galaxy. We find strong trends between black hole growth, as measured by dust-attenuation-corrected [O(More)
Proliferative oligodendrocyte progenitor cells (OPs) express large, delayed outward-rectifying K(+) currents (I(K)), whereas nondividing immature and mature oligodendrocytes display much smaller I(K). Here, we show that up-regulation of I(K) occurs in G(1) phase of the cell cycle in purified cultured OPs and is the result of an RNA synthesis-dependent,(More)
We present 13 Broad Absorption Line (BAL) quasars, including 12 new objects, which were identified in the Sloan Digital Sky Survey (SDSS) and matched within 2 ′′ to sources in the FIRST radio survey catalog. The surface density of this sample of radio BAL quasars is 4.5 ± 1.2 per 100 deg 2 , i.e. approximately 4 times larger than previously found by the(More)
Detailed high-resolution observations of the innermost regions of nearby galaxies have revealed the presence of supermassive black holes. These black holes may interact with their host galaxies by means of 'feedback' in the form of energy and material jets; this feedback affects the evolution of the host and gives rise to observed relations between the(More)
The cosmological star formation rate in the combined Chandra Deep Fields North and South is derived from our X-Ray Luminosity Function for Galaxies in these Deep Fields. Mild evolution is seen up to redshift order unity with SFR ∼ (1 + z) 2.7. This is the first directly observed normal star-forming galaxy X-ray luminosity function (XLF) at cosmologically(More)
We use high signal-to-noise ratio long-slit spectra in the λλ3600-4700Å range of the twenty brightest northern Seyfert 2 galaxies to study the variation of the stellar population properties as a function of distance from the nucleus. In order to characterize the stellar population and other continuum sources (e.g. featureless continuum FC) we have measured(More)
We present a method to estimate the total gas column density, dust-togas and dust-to-metal ratios of distant galaxies from rest-frame optical spectra. The technique exploits the sensitivity of certain optical lines to changes in depletion of metals onto dust grains and uses photo-ionization models to constrain these physical ratios along with the(More)
We present data from Integral Field Spectroscopy for 3 supercompact UV-Luminous Galaxies (ScUVLGs). As nearby (z ∼ 0.2), compact (R 50 ∼1-2 kpc), bright Paschen-α sources, with unusually high star formation rates (SFR=3−100 M ⊙ yr −1), ScUVLGs are an ideal population for studying detailed kinematics and dynamics in actively star-forming galaxies. In(More)
We present an atlas of the central regions of 75 Seyfert galaxies imaged in the near-UV with the Advanced Camera for Surveys of the Hubble Space Telescope at an average resolution of ∼10 pc. These data complement archival high resolution data from the Space Telescope at optical and near-IR wavelengths, creating an extremely valuable dataset for astronomers(More)