Publications (11)
Exploring the Spectral Energy Distributions of Luminous Broad Absorption Line Quasars at High Redshift
Harum Ahmed, Sarah C. Gallagher, Ohad Shemmer +4
We present the multiwavelength spectral energy distributions (SEDs) for 65 luminous broad absorption line (BAL) quasars with redshifts from the Gemi…
Gemini Near Infrared SpectrographDistant Quasar Survey: the Chandra View
Andrea Marlar, Ohad Shemmer, Michael S. Brotherton +5
We present Chandra observations of 63 sources from the Gemini Near Infrared SpectrographDistant Quasar Survey (GNIRS-DQS) of which 54 were targeted by snapshot observations in C…
Gemini Near Infrared Spectrograph - Distant Quasar Survey: Prescriptions for Calibrating UV-Based Estimates of Supermassive Black Hole Masses in High-Redshift Quasars
Cooper Dix, Brandon Matthews, Ohad Shemmer +10
The most reliable single-epoch supermassive black hole mass () estimates in quasars are obtained by using the velocity widths of low-ionization emission lines, typicall…
Rest-Frame Optical Spectroscopy of Ten z 2 Weak Emission-Line Quasars
Ying Chen, Bin Luo, W. N. Brandt +7
We present near-infrared spectroscopy of ten weak emission-line quasars (WLQs) at redshifts of , obtained with the Palomar 200-inch Hale Telescope. WLQs are an exceptional…
Gemini Near Infrared Spectrograph -- Distant Quasar Survey: Rest-Frame Ultraviolet-Optical Spectral Properties of Broad Absorption Line Quasars
Harum Ahmed, Ohad Shemmer, Brandon Matthews +12
We present the rest-frame ultraviolet-optical spectral properties of 65 broad absorption line (BAL) quasars from the Gemini Near Infrared Spectrograph-Distant Quasar Survey (GNIRS-…
Shedding New Light on Weak Emission-Line Quasars in the C-H Parameter Space
Trung Ha, Cooper Dix, Brandon M. Matthews +20
Weak emission-line quasars (WLQs) are a subset of Type 1 quasars that exhibit extremely weak LyN V 1240 and/or C IV 1549 emission lines. We investigate the relationshi…
Placing High-Redshift Quasars in Perspective: a Catalog of Spectroscopic Properties from the Gemini Near Infrared Spectrograph -- Distant Quasar Survey
Brandon M. Matthews, Ohad Shemmer, Cooper Dix +15
We present spectroscopic measurements for 226 sources from the Gemini Near Infrared Spectrograph - Distant Quasar Survey (GNIRS-DQS). Being the largest uniform, homogeneous survey…
Prescriptions for Correcting Ultraviolet-Based Redshifts for Luminous Quasars at High Redshift
Cooper Dix, Ohad Shemmer, Michael S. Brotherton +3
High-redshift quasars typically have their redshift determined from rest-frame ultraviolet (UV) emission lines. However, these lines, and more specifically the prominent C IV $λ15…
Can X-ray Observations Improve Optical-UV-based Accretion-Rate Estimates for Quasars?
Andrea Marlar, Ohad Shemmer, Michael S. Brotherton +2
Current estimates of the normalized accretion rates of quasars (L/L_Edd), rely on measuring the velocity widths of broad optical-UV emission lines (e.g., H and Mg II $\lambda28…
Systematically smaller single-epoch quasar black hole masses using a radius-luminosity relationship corrected for spectral bias
Jaya Maithil, Michael S. Brotherton, Ohad Shemmer +6
Determining black hole masses and accretion rates with better accuracy and precision is crucial for understanding quasars as a population. These are fundamental physical properties…
Gemini Near Infrared Spectrograph -- Distant Quasar Survey: Augmented Spectroscopic Catalog and a Prescription for Correcting UV-Based Quasar Redshifts
Brandon M. Matthews, Cooper Dix, Ohad Shemmer +13
Quasars at most often have redshifts measured from rest-frame ultraviolet emission lines. One of the most common such lines, C IV , shows blueshifts up to $…