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Analysis of NuSTAR and Suzaku observations of Cyg X-1 in the hard state: evidence for a truncated disc geometry
Parker, Michael; Zdziarski, Andrzej A.; Basak, Rupal +1 more
The geometry of the accretion flow in black hole X-ray binaries in the hard state, in particular the position of the disc inner edge, has been a subject of intense debate in recent years. We address this issue by performing a spectral study of simultaneous observations of Cyg X-1 in the hard state by NuSTAR and Suzaku. The same data were analysed …
Scientific Synergy between LSST and Euclid
Smith, Graham P.; Conselice, Christopher J.; Aubourg, Éric +34 more
Euclid and the Large Synoptic Survey Telescope (LSST) are poised to dramatically change the astronomy landscape early in the next decade. The combination of high-cadence, deep, wide-field optical photometry from LSST with high-resolution, wide-field optical photometry, and near-infrared photometry and spectroscopy from Euclid will be powerful for …
The Rest-frame Optical (900 nm) Galaxy Luminosity Function at z ∼ 4-7: Abundance Matching Points to Limited Evolution in the M STAR/M HALO Ratio at z ≥ 4
Muzzin, Adam; Labbé, Ivo; Bouwens, Rychard J. +4 more
We present the first determination of the galaxy luminosity function (LF) at z ∼ 4, 5, 6, and 7, in the rest-frame optical at {λ }{rest}∼ 900 {nm} (z‧ band). The rest-frame optical light traces the content in low-mass evolved stars (∼stellar mass—M *), minimizing potential measurement biases for M *. Moreover, it i…
On the metallicity dependence of the [Y/Mg]-age relation for solar-type stars
McMillan, Paul J.; Feltzing, Sofia; Howes, Louise M. +1 more
Several recent studies of solar twins in the solar neighbourhood have shown a tight correlation between various elemental abundances and age, in particular [Y/Mg]. If this relation is real and valid for other types of stars as well as elsewhere in the Galaxy, it would provide a very powerful tool to derive ages of stars without the need to resort …
No Overdensity of Lyman-Alpha Emitting Galaxies around a Quasar at z ∼ 5.7
Walter, F.; Decarli, R.; Overzier, R. +4 more
Bright quasars, observed when the universe was less than one billion years old (z > 5.5), are known to host massive black holes (∼109 M⊙) and are thought to reside in the center of massive dark matter overdensities. In this picture, overdensities of galaxies are expected around high-redshift quasars. However, observations …
Red clump stars and Gaia: calibration of the standard candle using a hierarchical probabilistic model
Bovy, Jo; Leistedt, Boris; Hogg, David W. +1 more
Distances to individual stars in our own Galaxy are critical in order to piece together the nature of its velocity and spatial structure. Core helium burning red clump (RC) stars have similar luminosities, are abundant throughout the Galaxy and thus constitute good standard candles. We build a hierarchical probabilistic model to quantify the quali…
High-precision abundances of elements in Kepler LEGACY stars. Verification of trends with stellar age
Christensen-Dalsgaard, J.; Grundahl, F.; Slumstrup, D. +3 more
Context. A previous study of solar twin stars has revealed the existence of correlations between some abundance ratios and stellar age providing new knowledge about nucleosynthesis and Galactic chemical evolution.
Aims: High-precision abundances of elements are determined for stars with asteroseismic ages in order to test the solar twin relat…
Ultra-diffuse and Ultra-compact Galaxies in the Frontier Fields Cluster Abell 2744
van Dokkum, Pieter; Romanowsky, Aaron J.; Abraham, Roberto +3 more
We report the discovery of a large population of ultra-diffuse galaxies (UDGs) in the massive galaxy cluster Abell 2744 (z = 0.308) as observed by the Hubble Frontier Fields program. Since this cluster is ∼5 times more massive than Coma, our observations allow us to extend 0.7 dex beyond the high-mass end of the relationship between UDG abundance …
Updating the (supermassive black hole mass)-(spiral arm pitch angle) relation: a strong correlation for galaxies with pseudobulges
Graham, Alister W.; Davis, Benjamin L.; Seigar, Marc S.
We have conducted an image analysis of the (current) full sample of 44 spiral galaxies with directly measured supermassive black hole (SMBH) masses, MBH, to determine each galaxy's logarithmic spiral arm pitch angle, ϕ. For predicting black hole masses, we have derived the relation: log (MBH/M⊙) = (7.01 ± 0.07) - (…
Galactic masers: Kinematics, spiral structure and the disk dynamic state
Dambis, A. K.; Bobylev, V. V.; Bajkova, A. T. +3 more
We applied the currently most comprehensive version of the statistical-parallax technique to derive the kinematical parameters of the maser sample with 136 sources. Our kinematic model comprises the overall rotation of the Galactic disk and the spiral density-wave effects, and the variation of radial velocity dispersion with Galactocentric distanc…