Search Publications
Nonparametric Dark Energy Reconstruction Using the Tomographic Alcock-Paczynski Test
Sabiu, Cristiano G.; Park, Hyunbae; Li, Yun-He +7 more
The tomographic Alcock-Paczynski (AP) method can result in tight cosmological constraints by using small and intermediate clustering scales of the large-scale structure of the galaxy distribution. By focusing on the redshift dependence, the AP distortion can be distinguished from the distortions produced by the redshift space distortions. In this …
On the High-energy Emissions of Compact Objects Observed with INTEGRAL SPI: Event Selection Impact on Source Spectra and Scientific Results for the Bright Sources Crab Nebula, GS 2023+338 and MAXI J1820+070
Jourdain, Elisabeth; Roques, Jean-Pierre
The Spectrometer on INTEGRAL (SPI) instrument has observed the hard X-ray sky from 20 keV up to a few MeV for more than 15 yr. In this energy domain, the main emitters are compact objects for which SPI provides spectral information of prime interest. Recently, two transient sources reached very unusual flux levels and have been detected up to a fe…
Chemical and Kinematic Analysis of CN-strong Metal-poor Field Stars in LAMOST DR3
Shi, Jianrong; Fernández-Trincado, J. G.; Zamora, Olga +5 more
The large amount of chemical and kinematic information available in large spectroscopic surveys has inspired the search for chemically peculiar stars in the field. Though these metal-poor field stars ([Fe/H] < -1) are commonly enriched in nitrogen, their detailed spatial, kinematic, and chemical distributions suggest that various groups may exi…
High-resolution Optical Spectroscopy of Stars in the Sylgr Stellar Stream
Roederer, Ian U.; Gnedin, Oleg Y.
We observe two metal-poor main-sequence stars that are members of the recently discovered Sylgr stellar stream. We present radial velocities, stellar parameters, and abundances for 13 elements derived from high-resolution optical spectra collected using the Magellan Inamori Kyocera Echelle spectrograph. The two stars have identical compositions (w…
Spectroscopic Confirmation of Five Galaxy Clusters at z > 1.25 in the 2500 deg2 SPT-SZ Survey
Bayliss, M. B.; Sharon, K.; Gladders, M. D. +29 more
We present spectroscopic confirmation of five galaxy clusters at 1.25 < z < 1.5, discovered in the 2500 deg2 South Pole Telescope Sunyaev-Zel’dovich (SZ) survey. These clusters, taken from a mass-limited sample with a nearly redshift-independent selection function, have multiwavelength follow-up imaging data from the X-ray to near…
Effective Temperatures of Low-mass Stars from High-resolution H-band Spectroscopy
Kesseli, Aurora Y.; Muirhead, Philip S.; Johns-Krull, Christopher M. +9 more
High-resolution, near-infrared spectra will be the primary tool for finding and characterizing Earth-like planets around low-mass stars. Yet, the properties of exoplanets cannot be precisely determined without accurate and precise measurements of the host star. Spectra obtained with the Immersion Grating Infrared Spectrometer simultaneously provid…
Titan Surface Temperatures during the Cassini Mission
Flasar, F. M.; Coustenis, A.; Achterberg, R. K. +11 more
By the close of the Cassini mission in 2017 the Composite Infrared Spectrometer had recorded surface brightness temperatures on Titan for 13 yr (almost half a Titan year). We mapped temperatures in latitude from pole to pole in seven time segments from northern mid-winter to northern summer solstice. At the beginning of the mission the warmest tem…
Fast-cadence TESS Photometry and Doppler Tomography of the Asynchronous Polar CD Ind: A Revised Accretion Geometry from Newly Proposed Spin and Orbital Periods
Garnavich, Peter; Littlefield, Colin; Szkody, Paula +5 more
The Transiting Exoplanet Survey Satellite observed the asynchronous polar (AP) CD Ind at a 2 min cadence almost continuously for 28 days in 2018, covering parts of five consecutive cycles of the system’s 7.3 day beat period. These observations provide the first uninterrupted photometry of a full spin-orbit beat cycle of an AP. Twice per beat cycle…
The Acceleration of Energetic Particles at Coronal Shocks and Emergence of a Double Power-law Feature in Particle Energy Spectra
Chen, Yao; Giacalone, Joe; Guo, Fan +1 more
We present numerical modeling of particle acceleration at coronal shocks propagating through a streamer-like magnetic field by solving the Parker transport equation with spatial diffusion both along and across the magnetic field. We show that the location on the shock where the high-energy particle intensity is the largest, depends on the energy o…
Compact Star-forming Galaxies as Old Starbursts Becoming Quiescent
Ivison, R. J.; Gómez-Guijarro, C.; Magdis, G. E. +8 more
Optically compact star-forming galaxies (SFGs) have been proposed as immediate progenitors of quiescent galaxies, although their origin and nature are debated. Were they formed in slow secular processes or in rapid merger-driven starbursts? Answering this question would provide fundamental insight into how quenching occurs. We explore the location…