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Reversal of Fortune: Increased Star Formation Efficiencies in the Early Histories of Dwarf Galaxies?
Conroy, Charlie; Weisz, Daniel R.; Madau, Piero
On dwarf galaxy scales, the different shapes of the galaxy stellar mass function and the dark halo mass function require a star-formation efficiency (SFE) in these systems that is currently more than 1 dex lower than that of Milky Way-size halos. Here, we argue that this trend may actually be reversed at high redshift. Specifically, by combining t…
Exploring the X-Ray and γ-Ray Properties of the Redback Millisecond Pulsar PSR J1723-2837
Cheng, K. S.; Takata, J.; Kong, A. K. H. +5 more
We have investigated the X-ray and γ-ray properties of the redback millisecond pulsar PSR J1723-2837 with XMM-Newton, Chandra, and Fermi. We have discovered the X-ray orbital modulation of this binary system with a minimum that coincides with the phases of radio eclipse. The X-ray emission is clearly non-thermal in nature, which can be described w…
The Active Galactic Nucleus Population in X-Ray-selected Galaxy Groups at 0.5 < z < 1.1
Mulchaey, John S.; Bauer, Franz E.; Finoguenov, Alexis +6 more
We use Chandra data to study the incidence and properties of active galactic nuclei (AGNs) in 16 intermediate redshift (0.5 < z < 1.1) X-ray-selected galaxy groups in the Chandra Deep Field-South. We measure an AGN fraction of f(LX,H \gt 1042;MR < {-20}) = 8.0-2.3+3.0% at \bar{z} ∼ 0.…
Probing interstellar extinction near the 30 Doradus nebula with red giant stars
Girardi, Léo; Panagia, Nino; De Marchi, Guido
We have studied the interstellar extinction in a field of ∼ 3 arcmin × 3 arcmin located about 6 arcmin southwest of 30 Doradus in the Large Magellanic Cloud (LMC). Hubble Space Telescope observations in the U, B, V, I and Hα bands reveal patchy extinction in this field. The colour-magnitude diagram (CMD) shows an elongated stellar sequence, almost…
HST/COS Detection of Deuterated Molecular Hydrogen in a Damped Lyα System at z = 0.18
Sembach, Kenneth R.; Tumlinson, Jason; Thom, Christopher +2 more
We report on the detection of deuterated molecular hydrogen, HD, at z = 0.18. HD and H2 are detected in HST/COS data of a low-metallicity (Z ~ 0.07 Z ⊙) damped Lyα (DLA) system at z = 0.18562 toward QSO B0120-28, with log N(H I) = 20.50 ± 0.10. Four absorption components are clearly resolved in H2, while two compon…
On nonlinear cascades and resonances in the outer magnetosphere
Kozak, L.; Amata, E.; Kronberg, E. A. +10 more
The paper addresses nonlinear phenomena that control the interaction between plasma flow (solar wind) and magnetic barrier (magnetosphere). For the first time we demonstrate that the dominant solar wind kinetic energy: (i) excites boundary resonances and their harmonics which modulate plasma jets under the bow shock; (ii) produces discrete three-w…
The Herschel Cold Debris Disks: Confusion with the Extragalactic Background at 160 µm
Rieke, George H.; Gáspár, András
The Herschel "DUst around NEarby Stars" (DUNES) survey has found a number of debris disk candidates that are apparently very cold, with temperatures near 22 K. It has proven difficult to fit their spectral energy distributions with conventional models for debris disks. Given this issue, we carefully examine the alternative explanation that the det…
Non-circular features in Saturn’s D ring: D68
Hedman, M. M.; Burns, J. A.; Showalter, M. R. +1 more
D68 is a narrow ringlet located only 67,627 km (1.12 planetary radii) from Saturn’s spin axis. Images of this ringlet obtained by the Cassini spacecraft reveal that this ringlet exhibits persistent longitudinal brightness variations and a substantial eccentricity (ae=25±1 km). By comparing observations made at different times, we confirm that the …
Seasonal and radial trends in Saturn’s thermal plasma between the main rings and Enceladus
Johnson, R. E.; Elrod, M. K.; Tseng, W. -L. +1 more
A goal of Cassini's extended mission is to examine the seasonal variations of Saturn's magnetosphere, moons, and rings. Recently we showed that the thermal plasma between the main rings and Enceladus exhibited a time dependence that we attributed to a seasonally variable source of oxygen from the main rings (Elrod, M.K., Tseng, W.-L., Wilson, R.J.…
Locating star-forming regions in quasar host galaxies
Netzer, H.; Shemmer, O.; Lutz, Dieter +5 more
We present a study of the morphology and intensity of star formation in the host galaxies of eight Palomar-Green quasars using observations with the Hubble Space Telescope. Our observations are motivated by recent evidence for a close relationship between black hole growth and the stellar mass evolution in its host galaxy. We use narrow-band [O II…