Search Publications
Studying the Ultraviolet Spectrum of the First Spectroscopically Confirmed Supernova at Redshift Two
Benoit-Lévy, A.; Bechtol, K.; Zheng, W. +89 more
We present observations of DES16C2nm, the first spectroscopically confirmed hydrogen-free superluminous supernova (SLSN-I) at redshift z≈ 2. DES16C2nm was discovered by the Dark Energy Survey (DES) Supernova Program, with follow-up photometric data from the Hubble Space Telescope, Gemini, and the European Southern Observatory Very Large Telescope …
Optical Counterparts of Ultraluminous X-Ray Sources NGC 4559 X-10 and NGC 4395 ULX-1
Vinokurov, A.; Atapin, K.; Fabrika, S.
We study the optical counterparts of ultraluminous X-ray sources (ULXs) NGC 4559 X-10 and NGC 4395 ULX-1. Their absolute magnitudes, after taking reddening into account, are M V ≈ -5.3 and M V ≈ -6.2, respectively. The spectral energy distribution (SED) of the NGC 4559 X-10 counterpart is well fitted by a spectrum of an A…
On the Impact of Helium Content on the RR Lyrae Distance Scale
Marconi, M.; Castellani, M.; Bono, G. +3 more
We constructed new sets of He-enhanced (Y = 0.30, Y = 0.40) nonlinear, time-dependent convective hydrodynamical models of RR Lyrae (RRL) stars covering a broad range in metal abundances (Z = 0.0001-0.02). The increase in He content from the canonical value (Y = 0.245) to Y = 0.30-0.40 causes a simultaneous increase in stellar luminosity and in pul…
Late-time Flattening of Type Ia Supernova Light Curves: Constraints from SN 2014J in M82
Baade, Dietrich; Sparks, William B.; Wang, Lifan +11 more
The very nearby Type Ia supernova 2014J in M82 offers a rare opportunity to study the physics of thermonuclear supernovae at extremely late phases (≳800 days). Using the Hubble Space Telescope, we obtained 6 epochs of high-precision photometry for SN 2014J from 277 days to 1181 days past the B-band maximum light. The reprocessing of electrons and …
The z = 0.54 LoBAL Quasar SDSS J085053.12+445122.5. I. Spectral Synthesis Analysis Reveals a Massive Outflow
Gallagher, Sarah C.; Terndrup, Donald M.; Leighly, Karen M. +2 more
We introduce SimBAL, a novel spectral-synthesis procedure that uses grids of ionic column densities generated by the photoionization code Cloudy and a Bayesian model calibration to forward-model broad absorption-line quasar (BALQ) spectra. We used SimBAL to analyze the Hubble Space Telescope Cosmic Origins Spectrograph (COS) spectrum of the low-re…
Evidence of Environmental Quenching at Redshift z ≈ 2
Ferguson, Henry C.; Giavalisco, Mauro; Ji, Zhiyuan +5 more
We report evidence of environmental quenching among galaxies at redshifts of ≈2, namely the probability that a galaxy quenches its star formation activity is enhanced in the regions of space in proximity of other quenched, more massive galaxies. The effect is observed as strong clustering of quiescent galaxies around quiescent galaxies on angular …
Hubble Space Telescope Wide Field Camera 3 Identifies an r p = 1 Kpc Dual Active Galactic Nucleus in the Minor Galaxy Merger SDSS J0924+0510 at z = 0.1495
Shen, Yue; Strauss, Michael A.; Greene, Jenny E. +2 more
Kiloparsec-scale dual active galactic nuclei (AGNs) are active supermassive black hole pairs co-rotating in galaxies with separations of less than a few kpc. Expected to be a generic outcome of hierarchical galaxy formation, their frequency and demographics remain uncertain. We have carried out an imaging survey with the Hubble Space Telescope (HS…
Evolution of the Solar Lyα Line Profile during the Solar Cycle
Bzowski, Maciej; Kubiak, Marzena A.; Sokół, Justyna M. +1 more
Recent studies of interstellar neutral (ISN) hydrogen observed by the Interstellar Boundary Explorer (IBEX) suggested that the present understanding of the radiation pressure acting on hydrogen atoms in the heliosphere should be revised. There is a significant discrepancy between theoretical predictions of the ISN H signal using the currently used…
Gas Contents of Galaxy Groups from Thermal Sunyaev-Zel’dovich Effects
Wang, Huiyuan; Ma, Yin-Zhe; Yang, Xiaohu +4 more
A matched filter technique is applied to the Planck all-sky Compton y-parameter map to measure the thermal Sunyaev-Zel’dovich (tSZ) effect produced by galaxy groups of different halo masses selected from large redshift surveys in the low-z universe. Reliable halo mass estimates are available for all of the groups, which allows us to bin groups of …
Time Stamps of Vertical Phase Mixing in the Galactic Disk from LAMOST/Gaia Stars
Zhang, Yong; Tian, Hai-Jun; Wu, Yue +2 more
The perturbation mechanism of the Galactic disk is a long-standing puzzle. The imprints from perturbations provide important diagnostics concerning the disk’s formation and evolution. Here we try to constrain when the vertical perturbation took place in the disk by tracking the phase-mixing history. First, we clearly depict the spiral structures o…