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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 …
Revisiting Kepler-444. I. Seismic modeling and inversions of stellar structure
Buldgen, G.; Farnir, M.; Khan, S. +10 more
Context. The CoRoT and Kepler missions have paved the way for synergies between exoplanetology and asteroseismology. The use of seismic data helps providing stringent constraints on the stellar properties which directly impact the results of planetary studies. Amongst the most interesting planetary systems discovered by Kepler, Kepler-444 is uniqu…
Extraction of globular clusters members with Gaia DR2 astrometry
Bustos Fierro, Iván H.; Calderón, J. H.
In this work, we present a method to identify possible members of globular clusters using data from Gaia DR2. The method consists of two stages: the first one based on a clustering algorithm, and the second one based on the analysis of the projected spatial distribution of stars with different proper motions. In order to confirm that the clusters …
The core of the massive cluster merger MACS J0417.5-1154 as seen by VLT/MUSE
Mahler, Guillaume; Richard, Johan; Massey, Richard +11 more
We present a multiwavelength analysis of the core of the massive galaxy cluster MACS J0417.5-1154 (z = 0.441). Our analysis takes advantage of Very Large Telescope/Multi-Unit Spectroscopic Explorer observations which allow the spectroscopic confirmation of three strongly lensed systems. System #1, nicknamed The Doughnut, consists of three images o…
Deriving the Hubble constant using Planck and XMM-Newton observations of galaxy clusters
Mazzotta, Pasquale; Sereno, Mauro; Rasia, Elena +2 more
The possibility of determining the value of the Hubble constant using observations of galaxy clusters in X-ray and microwave wavelengths through the Sunyaev Zel'dovich (SZ) effect has long been known. Previous measurements have been plagued by relatively large errors in the observational data and severe biases induced, for example, by cluster tria…
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…
On migration of dust and ice grains on the surface of the rotating comet nucleus
Wesołowski, M.; Gronkowski, P.; Tralle, I.
In the paper the migration of dust and ice grains over the surface of the comet nucleus is considered and analysed. This phenomenon is a consequence of interplay between the components of three forces tangential to the surface of comet nucleus and acting on the comet's grain. These forces are the gravity of the comet's nucleus, the frictional forc…
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…
K2 observations of the sdBV + dM/bd binaries PHL 457 and EQ Psc
Reed, M. D.; Jeffery, C. S.; Baran, A. S. +5 more
We present an analysis of two pulsating subdwarf B stars PHL 457 and EQ Psc observed during the K2 mission. The K2 light curves of both stars show variation consistent with irradiation of a cooler companion by the hot subdwarf. They also show higher frequency oscillations consistent with pulsation. Using new spectroscopic data, we measured the rad…