• Publications
  • Influence
A Search for “Dwarf'' Seyfert Nuclei. III. Spectroscopic Parameters and Properties of the Host Galaxies
We have completed an optical spectroscopic survey of the nuclear regions (r < 200 pc) of a large sample of nearby galaxies. Although the main objectives of the survey are to search for low-luminosity
The Chandra Deep Field North Survey. XIII. 2 Ms Point-Source Catalogs
We present point-source catalogs for the ?2 Ms exposure of the Chandra Deep Field North, currently the deepest X-ray observation of the universe in the 0.5?8.0 keV band. Five hundred and three (503)
The thermal history of the intergalactic medium
At redshifts z≳2, most of the baryons reside in the smooth intergalactic medium which is responsible for the low column density Lyα forest. This photoheated gas follows a tight temperature–density
Abundance Patterns in the Draco, Sextans, and Ursa Minor Dwarf Spheroidal Galaxies
The Keck I telescope and the High Resolution Echelle Spectrometer (HIRES) have been used to obtain spectra for red giant stars belonging to the Draco, Sextans, and Ursa Minor dwarf spheroidal (dSph)
A Search for ``Dwarf'' Seyfert Nuclei. V. Demographics of Nuclear Activity in Nearby Galaxies
We use the sample of emission-line nuclei derived from a recently completed optical spectroscopic survey of nearby galaxies to quantify the incidence of local (z ≈ 0) nuclear activity. Particular
Abundances at High Redshifts: The Chemical Enrichment History of Damped Lyα Galaxies
We study the elemental abundances of C, N, O, Al, Si, S, Cr, Mn, Fe, Ni, and Zn in a sample of 14 damped Lyα systems (galaxies) with H I column density N(H I) ≥ 1020 cm−2, using high-quality spectra
Mg II absorption in the spectra of 103 QSOs : implications for the evolution of gas in high-redshift galaxies
Spectra of 103 low- and intermediate-redshift QSOs (roughly half of which are radio sources) have been obtained with a resolution of 4-6 A in order to investigate the statistics of Mg II λλ2796, 2803
A Search for “Dwarf” Seyfert Nuclei. IV. Nuclei with Broad Hα Emission
We present the results of an optical spectroscopic survey designed to search for low-luminosity "dwarf" Seyfert nuclei in a magnitude-limited (BT ≤ 12.5 mag) sample of 486 bright, northern galaxies.
The Chandra Deep Field North Survey. V. 1 Ms Source Catalogs
An extremely deep X-ray survey (≈1 Ms) of the Hubble Deep Field North (HDF-N) and its environs (≈450 arcmin2) has been performed with the Advanced CCD Imaging Spectrometer on board the Chandra X-Ray