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Firehose and Mirror Instabilities in a Collisionless Shearing Plasma
Kunz, Matthew W.; Schekochihin, Alexander A.; Stone, James M.
Hybrid-kinetic numerical simulations of firehose and mirror instabilities in a collisionless plasma are performed in which pressure anisotropy is driven as the magnetic field is changed by a persistent linear shear S. For a decreasing field, it is found that mostly oblique firehose fluctuations grow at ion Larmor scales and saturate with energies …
A fast and long-lived outflow from the supermassive black hole in NGC 5548
Kaastra, J. S.; Harrison, F. A.; Nandra, K. +31 more
Supermassive black holes in the nuclei of active galaxies expel large amounts of matter through powerful winds of ionized gas. The archetypal active galaxy NGC 5548 has been studied for decades, and high-resolution x-ray and ultraviolet (UV) observations have previously shown a persistent ionized outflow. An observing campaign in 2013 with six spa…
The Long Lives of Giant Clumps and the Birth of Outflows in Gas-rich Galaxies at High Redshift
Amram, Philippe; Daddi, Emanuele; Juneau, Stéphanie +13 more
Star-forming disk galaxies at high redshift are often subject to violent disk instability, characterized by giant clumps whose fate is yet to be understood. The main question is whether the clumps disrupt within their dynamical timescale (<=50 Myr), like the molecular clouds in today's galaxies, or whether they survive stellar feedback for more…
Water vapour absorption in the clear atmosphere of a Neptune-sized exoplanet
Deming, Drake; Madhusudhan, Nikku; Knutson, Heather +6 more
Transmission spectroscopy has so far detected atomic and molecular absorption in Jupiter-sized exoplanets, but intense efforts to measure molecular absorption in the atmospheres of smaller (Neptune-sized) planets during transits have revealed only featureless spectra. From this it was concluded that the majority of small, warm planets evolve to su…
Lens Models and Magnification Maps of the Six Hubble Frontier Fields Clusters
Coe, Dan; Sharon, Keren; Johnson, Traci L. +3 more
We present strong-lensing models as well as mass and magnification maps for the cores of the six Hubble Space Telescope (HST) Frontier Fields galaxy clusters. Our parametric lens models are constrained by the locations and redshifts of multiple image systems of lensed background galaxies. We use a combination of photometric redshifts and spectrosc…
The Typecasting of Active Galactic Nuclei: Mrk 590 no Longer Fits the Role
Martini, P.; Peterson, B. M.; Pogge, R. W. +9 more
We present multiwavelength observations that trace more than 40 yr in the life of the active galactic nucleus (AGN) in Mrk 590, traditionally known as a classic Seyfert 1 galaxy. From spectra recently obtained from Hubble Space Telescope, Chandra, and the Large Binocular Telescope, we find that the activity in the nucleus of Mrk 590 has diminished…
A Substantial Population of Massive Quiescent Galaxies at z ~ 4 from ZFOURGE
Papovich, Casey; Dickinson, Mark; Inami, Hanae +21 more
We report the likely identification of a substantial population of massive M ~ 1011 M ⊙ galaxies at z ~ 4 with suppressed star formation rates (SFRs), selected on rest-frame optical to near-IR colors from the FourStar Galaxy Evolution Survey (ZFOURGE). The observed spectral energy distributions show pronounced breaks, sampled…
Validation of Kepler's Multiple Planet Candidates. II. Refined Statistical Framework and Descriptions of Systems of Special Interest
Torres, Guillermo; Marcy, Geoffrey W.; Lissauer, Jack J. +11 more
We extend the statistical analysis performed by Lissauer et al. in 2012, which demonstrates that the overwhelming majority of Kepler candidate multiple transiting systems (multis) represents true transiting planets, and we develop therefrom a procedure to validate large numbers of planet candidates in multis as bona fide exoplanets. We show that t…
Current dark matter annihilation constraints from CMB and low-redshift data
Madhavacheril, Mathew S.; Sehgal, Neelima; Slatyer, Tracy R.
Updated constraints on the dark matter cross section and mass are presented combining cosmic microwave background (CMB) power spectrum measurements from Planck, WMAP9, ACT, and SPT as well as several low-redshift data sets (BAO, HST, and supernovae). For the CMB data sets, we combine WMAP9 temperature and polarization data for l ≤431 with Planck t…
A Large Catalog of Accurate Distances to Molecular Clouds from PS1 Photometry
Price, P. A.; Rix, H. -W.; Chambers, K. C. +12 more
Distance measurements to molecular clouds are important but are often made separately for each cloud of interest, employing very different data and techniques. We present a large, homogeneous catalog of distances to molecular clouds, most of which are of unprecedented accuracy. We determine distances using optical photometry of stars along lines o…