Search Publications
Quasi-periodic Pulsations during the Impulsive and Decay phases of an X-class Flare
Hayes, L. A.; Gallagher, P. T.; Dennis, B. R. +3 more
Quasi-periodic pulsations (QPPs) are often observed in X-ray emission from solar flares. To date, it is unclear what their physical origins are. Here, we present a multi-instrument investigation of the nature of QPP during the impulsive and decay phases of the X1.0 flare of 2013 October 28. We focus on the character of the fine structure pulsation…
The Infrared Spectral Properties of Magellanic Carbon Stars
van Loon, J. Th.; Sahai, R.; Wood, P. R. +12 more
The Infrared Spectrograph on the Spitzer Space Telescope observed 184 carbon stars in the Magellanic Clouds. This sample reveals that the dust-production rate (DPR) from carbon stars generally increases with the pulsation period of the star. The composition of the dust grains follows two condensation sequences, with more SiC condensing before amor…
The near-to-mid infrared spectrum of quasars
Alonso-Herrero, Almudena; Hatziminaoglou, Evanthia; Hernán-Caballero, Antonio +1 more
We analyse a sample of 85 luminous (log (νLν(3 µm)/erg s-1) > 45.5) quasars with rest frame ∼2-11 µm spectroscopy from AKARI and Spitzer. Their high luminosity allows a direct determination of the near-infrared quasar spectrum free from host galaxy emission. A semi-empirical model consisting of a single templat…
A Deep Campaign to Characterize the Synchronous Radio/X-Ray Mode Switching of PSR B0943+10
Tiengo, A.; Mereghetti, S.; Esposito, P. +14 more
Observations of PSR B0943+10 with XMM-Newton and the LOFAR, LWA, and Arecibo radio telescopes in 2014 November confirm the synchronous X-ray/radio switching between a radio-bright (B) mode and a radio-quiet (Q) mode, in which the X-ray flux is a factor ∼2.4 higher than in the B-mode. We discovered X-ray pulsations during the B-mode (0.5-2 keV puls…
Low Gas Fractions Connect Compact Star-forming Galaxies to Their z ~ 2 Quiescent Descendants
Weiner, Benjamin J.; Bezanson, Rachel; Williams, Christina C. +3 more
Early quiescent galaxies at z∼ 2 are known to be remarkably compact compared to their nearby counterparts. Possible progenitors of these systems include galaxies that are structurally similar, but are still rapidly forming stars. Here, we present Karl G. Jansky Very Large Array (VLA) observations of the CO(1-0) line toward three such compact, star…
Absorption-line Spectroscopy of Gravitationally Lensed Galaxies: Further Constraints on the Escape Fraction of Ionizing Photons at High Redshift
Stark, Daniel P.; Ellis, Richard S.; Zitrin, Adi +2 more
The fraction of ionizing photons escaping from high-redshift star-forming galaxies is a key obstacle in evaluating whether galaxies were the primary agents of cosmic reionization. We previously proposed using the covering fraction of low-ionization gas, measured via deep absorption-line spectroscopy, as a proxy. We now present a significant update…
High Spatial Resolution Fe XII Observations of Solar Active Regions
Testa, Paola; De Pontieu, Bart; Hansteen, Viggo
We use UV spectral observations of active regions with the Interface Region Imaging Spectrograph (IRIS) to investigate the properties of the coronal Fe xii 1349.4 Å emission at unprecedented high spatial resolution (∼0.33″). We find that by using appropriate observational strategies (I.e., long exposures, lossless compression), Fe xii emission can…
An enhanced merger fraction within the galaxy population of the SSA22 protocluster at z = 3.1
Lehmer, B. D.; Alexander, D. M.; Matsuda, Y. +3 more
The overdense environments of protoclusters of galaxies in the early Universe (z > 2) are expected to accelerate the evolution of galaxies, with an increased rate of stellar mass assembly and black hole accretion compared to co-eval galaxies in the average density `field'. These galaxies are destined to form the passive population of massive ga…
The Lyman alpha reference sample. VII. Spatially resolved Hα kinematics
Verhamme, Anne; Cannon, John M.; Hayes, Matthew +19 more
We present integral field spectroscopic observations with the Potsdam Multi-Aperture Spectrophotometer of all 14 galaxies in the z ~ 0.1 Lyman Alpha Reference Sample (LARS). We produce 2D line-of-sight velocity maps and velocity dispersion maps from the Balmer α (Hα) emission in our data cubes. These maps trace the spectral and spatial properties …
O VI Emission Imaging of a Galaxy with the Hubble Space Telescope: a Warm Gas Halo Surrounding the Intense Starburst SDSS J115630.63+500822.1
Scarlata, Claudia; Hayes, Matthew; Östlin, Göran +3 more
We report results from a new Hubble Space Telescope campaign that targets the O VI λ λ 1032,1038 Å doublet in emission around intensely star-forming galaxies. The program aims to characterize the energy balance in starburst galaxies and gas cooling in the difficult-to-map coronal temperature regime of 2{--}5× {10}5 K. We present the fir…