Related papers: The FeII Optical Emission in AGN

We present evidence for a skewed distribution of UV FeII emission in quasars within candidate overdense regions spanning spatial scales of ~ 50 Mpc at 1.11 < z < 1.67, compared to quasars in field environments at comparable redshifts. The…

Absorption due to HeII Ly-alpha has been detected at low resolution in the spectra of four quasars between redshifts z = 2.74-3.29. We assess these observations, giving particular attention to the radiative transfer of the ionizing…

We present high resolution (R=80,000) spectroscopy of [NeII] emission from two young stars, GM Aur and AA Tau, which have moderate to high inclinations. The emission from both sources appears centered near the stellar velocity and is…

We considered the fourth catalog of gamma-ray point sources produced by the Fermi Large Area Telescope (LAT) and selected only jetted active galactic nuclei (AGN) or sources with no specific classification, but with a low-frequency…

The study of narrow-line Seyfert 1 galaxies (NLS1s) is now mostly limited to low redshift ($z<0.8$) because their definition requires the presence of the H$\beta$ emission line, which is redshifted out of the spectral coverage of major…

Accurate emission line fluxes from planetary nebulae (PNe) provide important constraints on the nature of the final phases of stellar evolution. Large, evolved PNe may trace the latest stages of PN evolution, where material from the AGB…

Near-infrared spectra of four QSOs located at $z>6$ are obtained with the OH-airglow suppressor mounted on the Subaru telescope. The FeII/MgII emission-line ratios of these QSOs are examined by the same fitting algorithm as in our previous…

We use JWST Near-Infrared Spectrograph (NIRSpec) observations from the the Cosmic Evolution Early Release survey (CEERS), GLASS-JWST ERS (GLASS), and JWST Advanced Deep Extragalactic Survey (JADES) to measure rest-frame optical…

We explore mechanisms to produce extremely high Ly-alpha/HeII flux ratios, or to enhance the observed number of Ly-alpha photons per incident ionizing photon, in extended AGN-photoionized nebulae at high-redshift. Using photoionization…

The [O II] 3727 emission line is often used as an indicator of star formation rate in extragalactic surveys, and it can be an equally effective tracer of star formation in systems containing luminous active galactic nuclei (AGNs). In order…

We report on the environments, kinematics, and SFH of [OII]-selected objects in the z=0.4 galaxy cluster A851, using Keck optical spectra. A large fraction (~55%) of cluster [OII] emitters show strong Balmer absorptions (>4A in equivalent…

We present near-infrared spectroscopic observations for a sample of ten optically faint luminous infrared galaxies (R-[24]> 14) using Keck NIRSPEC and Gemini NIRI. The sample is selected from a 24 micron Spitzer MIPS imaging survey of the…

We use Hubble Space Telescope WFC3 G102 and G141 grism spectroscopy to measure rest-optical emission-line ratios of 533 galaxies at $z\sim1.5$ in the CANDELS Ly$\alpha$ Emission at Reionization (CLEAR) survey. We compare…

We review constraints on models of the broad line region that are imposed by observations of the emission lines in Active Galactic Nuclei. Comparison of high and low ionization lines in sources with FWHM Hbeta < 4000 km/s points toward low…

We present a study of the gaseous and stellar emission in I Zw18, the most metal-poor star-forming galaxy known. Archival HST WFPC2 and FOS data have been used to analyze the spatial distribution of [OIII], Halpha, and HeII 4686. The latter…

We report the detection of complex Fe K line emission from a Chandra High Energy Transmission Grating Spectrometer observation of the Seyfert 1 galaxy IC 4329A. The line emission is double-peaked, one peak centered at ~6.3 keV, and the…

Most of the celestial gamma rays detected by the Large Area Telescope (LAT) aboard the Fermi Gamma-ray Space Telescope originate from the interstellar medium when energetic cosmic rays interact with interstellar nucleons and photons.…

We investigate the structure of the Mg II broad line emission region in a sample of 284 Type 1 active galactic nuclei (AGNs), through comparing the kinematical parameters of the broad Mg II and broad H$\beta$ lines. We found that the Mg II…

We present a new empirical template for iron emission in active galactic nuclei (AGN) covering the $4000-5600$ A range. The new template is based on a spectrum of the narrow-line Seyfert 1 galaxy Mrk 493 obtained with the Hubble Space…

The Wisconsin H-Alpha Mapper (WHAM) is a new facility dedicated to the study of faint optical emission lines from diffuse interstellar gas. During its first 18 months of operation, WHAM carried out a survey of the interstellar H-alpha…