Search Publications
Hα and 4000 Å Break Measurements for ~3500 K-selected Galaxies at 0.5 < z < 2.0
van Dokkum, Pieter G.; Franx, Marijn; Labbé, Ivo +3 more
We measure spectral features of ~3500 K-selected galaxies at 0.5 < z < 2.0 from high-quality medium-band photometry using a new technique. First, we divide the galaxy sample in 32 subsamples based on the similarities between the full spectral energy distributions (SEDs) of the galaxies. For each of these 32 galaxy types we construct a compos…
Limits on the local dark matter density
Read, Justin I.; Garbari, Silvia; Lake, George
We revisit systematics in determining the local dark matter density ρdm from the vertical motion of stars in the solar neighbourhood. Using a simulation of a Milky Way like galaxy, we determine the data quality required to detect ρdm at its expected local value. We introduce a new method for recovering ρdm that use…
Investigating coronal saturation and supersaturation in fast-rotating M-dwarf stars
Briggs, K. R.; Jeffries, R. D.; Evans, P. A. +2 more
At fast rotation rates, the coronal activity of G- and K-type stars has been observed to 'saturate' and then decline again at even faster rotation rates - a phenomenon dubbed 'supersaturation'. In this paper, we investigate coronal activity in fast-rotating M-dwarfs using deep XMM-Newton observations of 97 low-mass stars of known rotation period i…
A reflection origin for the soft and hard X-ray excess of Ark 120
Fabian, A. C.; Nardini, E.; Reis, R. C. +1 more
Over the last few years, several models have been proposed to interpret the widespread soft excess observed in the X-ray spectra of type 1 active galactic nuclei (AGN). In particular, reflection from the photoionized accretion disc blurred by relativistic effects has proven to be successful in reproducing both the spectral shape and the variabilit…
New star-forming galaxies at z≈ 7 from Wide Field Camera Three imaging
Wilkins, Stephen M.; Bunker, Andrew J.; Caruana, Joseph +1 more
The addition of Wide Field Camera Three on the Hubble Space Telescope has led to a dramatic increase in our ability to study the z > 6 Universe. The improvement in the near-infrared (NIR) sensitivity of WFC3 over previous instruments has enabled us to reach apparent magnitudes approaching 29 (AB). This allows us to probe the rest-frame UV conti…
Foreshock cavitons for different interplanetary magnetic field geometries: Simulations and observations
Russell, C. T.; Omidi, N.; Blanco-Cano, X. +1 more
Global hybrid (kinetic ions, fluid electrons) simulations have shown the existence of foreshock cavitons characterized by large depressions in plasma density and magnetic field magnitude, bounded by enhancements in these two parameters. Foreshock cavitons share some characteristics with reported foreshock cavities, but in contrast to the cavities …
Photometric and Spectroscopic Evolution of the IIP SN 2007it to Day 944
Welch, D. L.; Gallagher, J. S.; Barlow, M. J. +9 more
SN 2007it is a bright, Type IIP supernova which shows indications of both pre-existing and newly formed dust. The visible photometry shows a bright late-time luminosity, powered by the 0.09 M sun of 56Ni present in the ejecta. There is also a sudden drop in optical brightness after day 339, and a corresponding brightening in …
Equatorial glaciations on Mars revealed by gravitational collapse of Valles Marineris wallslopes
Mège, Daniel; Bourgeois, Olivier
Martian global climate models that account for evidence of past glaciations reported in tropical to mid-latitude regions of Mars predict accumulation of water ice in Valles Marineris during past periods of high obliquity. Observational evidence for such glaciations is given here. Topographic basement ridges of tectonic origin are common in Valles …
Black Hole Mass and Bulge Luminosity for Low-mass Black Holes
Ho, Luis C.; Greene, Jenny E.; Jiang, Yan-Fei
We study the scaling between bulge magnitude and central black hole (BH) mass in galaxies with virial BH masses <~ 106 M sun. Based on careful image decomposition of a snapshot Hubble Space Telescope I-band survey, we found that these BHs are found predominantly in galaxies with pseudobulges. Here we show that the M B…
Morphology, dynamics and plasma parameters of plumes and inter-plume regions in solar coronal holes
Llebaria, A.; Auchère, F.; Feng, L. +12 more
Coronal plumes, which extend from solar coronal holes (CH) into the high corona and—possibly—into the solar wind (SW), can now continuously be studied with modern telescopes and spectrometers on spacecraft, in addition to investigations from the ground, in particular, during total eclipses. Despite the large amount of data available on these promi…