Publications (14)
Unique Astrophysics in the Lyman Ultraviolet
Jason Tumlinson, Alessandra Aloisi, Gerard Kriss +24
There is unique and groundbreaking science to be done with a new generation of UV spectrographs that cover wavelengths in the "Lyman Ultraviolet" (LUV; 912 - 1216 Ang). There is no…
Quasar Outflows and AGN Feedback in the Far UV: HST/COS Observations of QSO HE0238-1904
Nahum Arav, Benoit Borguet, Carter Chamberlain +2
Spectroscopic observations of quasar outflows at rest-frame 500-1000 Angstrom have immense diagnostic power. We present analyses of such data, where absorption troughs from three i…
A FUSE Survey of Interstellar Molecular Hydrogen toward High-Latitude AGN
Kristen Gillmon, J. Michael Shull, Jason Tumlinson +1
We report results from a FUSE survey of interstellar molecular hydrogen (H2) along 45 sight lines to AGN at high Galactic latitudes (|b| > 20 degrees). Most (39 of 45) of the sight…
Softening of the Metagalactic Ionizing Background from Internal He II Absorption in Quasars
Michael Shull, Charles Danforth
Quasars and active galactic nuclei (AGN) are significant contributors to the metagalactic ionizing background at redshifts z < 3. Recent HST/COS composite spectra of AGN find a har…
Hubble-COS Observations of Galactic High-Velocity Clouds: Four AGN Sight Lines through Complex C
Michael Shull, Matthew Stevans, Charles Danforth +3
We report ultraviolet spectra of Galactic high-velocity clouds (HVCs) in Complex C, taken by the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope (HST), together wit…
The Warm Circum-Galactic Medium: 10^5-6 K Gas Associated with a Single Galaxy Halo or with an Entire Group of Galaxies?
John Stocke, Brian Keeney, Charles Danforth +3
In preparation for a Hubble Space Telescope (HST) observing project using the Cosmic Origins Spectrograph (COS), the positions of all AGN targets having high-S/N far-UV G130M spect…
Ultraviolet and X-ray Variability of the Seyfert 1.5 Galaxy Markarian 817
Lisa M. Winter, Charles Danforth, Ranjan Vasudevan +9
We present an investigation of the ultraviolet and X-ray spectra of the Seyfert 1.5 galaxy Markarian 817. The ultraviolet analysis includes two recent observations taken with the C…
Hubble/COS Observations of the Quasar HE 2347-4342: Probing the Epoch of He II Patchy Reionization at Redshifts z = 2.4-2.9
Michael Shull, Kevin France, Charles Danforth +2
We report ultraviolet spectra of the high-redshift (z_em = 2.9) quasar, HE 2347-4342, taken by the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope (HST). Spectra in…
The Photon Underproduction Crisis
Juna A. Kollmeier, David H. Weinberg, Benjamin D. Oppenheimer +9
We examine the statistics of the low-redshift Lyman-alpha forest from smoothed particle hydrodynamic simulations in light of recent improvements in the estimated evolution of the c…
The Cosmic Origins Spectrograph
James C. Green, Cynthia S. Froning, Steve Osterman +23
The Cosmic Origins Spectrograph (COS) is a moderate-resolution spectrograph with unprecedented sensitivity that was installed into the Hubble Space Telescope (HST) in May 2009, dur…
Gaia-EDR3 Parallax Distances to the Great Carina Nebula and its Star Clusters (Trumpler 14, 15, 16)
Michael Shull, Jeremy Darling, Charles Danforth
Using offset-corrected Gaia-EDR3 parallax measurements and spectrophotometric methods, we have determined distances for 69 massive stars in the Carina OB1 association and associate…
An Unbiased Far Ultraviolet Survey of Magellanic Cloud Supernova Remnants
Parviz Ghavamian, William P. Blair, Ravi Sankrit +2
We have undertaken a FUSE survey of Magellanic Cloud supernova remnants, looking primarily for O VI and C III emission lines. Work in earlier cycles with FUSE indicates that optica…
Far-Ultraviolet & Halpha Spectroscopy of SNR0057-7226 in the SMC HII Region N66
Charles Danforth, Ravi Sankrit, William Blair +2
N66/NGC346 is the largest and brightest HII region in the Small Magellanic Cloud and contains at least one known supernova remnant SNR0057-7226. Optical emission from the remnant i…
On the Redshift of the Very High Energy Blazar 3C 66A
Amy Furniss, Michele Fumagalli, Charles Danforth +2
As a bright gamma-ray source, 3C 66A is of great interest to the high-energy astrophysics community, having a potential for placing cosmological constraints on models for the extra…