Search Publications
Herschel PEP/HerMES: the redshift evolution (0 ≤ z ≤ 4) of dust attenuation and of the total (UV+IR) star formation rate density
Berta, S.; Magnelli, B.; Nordon, R. +20 more
Using new homogeneous luminosity functions (LFs) in the far-ultraviolet (FUV) from VVDS and in the far-infrared (FIR) from Herschel/PEP and Herschel/HerMES, we studied the evolution of the dust attenuation with redshift. With this information, we were able to estimate the redshift evolution of the total (FUV + FIR) star formation rate density (SFR…
A variable absorption feature in the X-ray spectrum of a magnetar
Mereghetti, Sandro; Esposito, Paolo; Turolla, Roberto +9 more
Soft-γ-ray repeaters (SGRs) and anomalous X-ray pulsars (AXPs) are slowly rotating, isolated neutron stars that sporadically undergo episodes of long-term flux enhancement (outbursts) generally accompanied by the emission of short bursts of hard X-rays. This behaviour can be understood in the magnetar model, according to which these sources are ma…
A statistical relation between the X-ray spectral index and Eddington ratio of active galactic nuclei in deep surveys
Sanders, D. B.; Taniguchi, Y.; Alexander, D. M. +33 more
We present an investigation into how well the properties of the accretion flow on to a supermassive black hole may be coupled to those of the overlying hot corona. To do so, we specifically measure the characteristic spectral index, Γ, of a power-law energy distribution, over an energy range of 2-10 keV, for X-ray selected, broad-lined radio-quiet…
The Ultra-long Gamma-Ray Burst 111209A: The Collapse of a Blue Supergiant?
Piro, L.; D'Elia, V.; Cutini, S. +8 more
We present optical, X-ray and gamma-ray observations of GRB 111209A, observed at a redshift of z = 0.677. We show that this event was active in its prompt phase for about 25000 s, making it the longest burst ever observed. This rare event could have been detected up to z ~ 1.4 in gamma-rays. Compared to other long gamma-ray bursts (GRBs), GRB 1112…
Dipolarization fronts as a consequence of transient reconnection: In situ evidence
André, M.; Hamrin, M.; Sitnov, M. I. +10 more
Dipolarization fronts (DFs) are frequently detected in the Earth's magnetotail from XGSM = -30 RE to XGSM = -7 RE. How these DFs are formed is still poorly understood. Three possible mechanisms have been suggested in previous simulations: (1) jet braking, (2) transient reconnection, and (3) spontaneous f…
A Correlation between Star Formation Rate and Average Black Hole Accretion in Star-forming Galaxies
Gorjian, Varoujan; Dey, Arjun; Alberts, Stacey +14 more
We present a measurement of the average supermassive black hole accretion rate (BHAR) as a function of the star formation rate (SFR) for galaxies in the redshift range 0.25 < z < 0.8. We study a sample of 1767 far-IR-selected star-forming galaxies in the 9 deg2 Boötes multi-wavelength survey field. The SFR is estimated using 250 &…
The Hinode Spectro-Polarimeter
Kubo, M.; Lites, B. W.; Ichimoto, K. +16 more
The joint Japan/US/UK Hinode mission includes the first large-aperture visible-light solar telescope flown in space. One component of the Focal Plane Package of that telescope is a precision spectro-polarimeter designed to measure full Stokes spectra with the intent of using those spectra to infer the magnetic-field vector at high precision in the…
A Significantly Low CO Abundance toward the TW Hya Protoplanetary Disk: A Path to Active Carbon Chemistry?
Cleeves, L. Ilsedore; Bergin, Edwin A.; Qi, Chunhua +2 more
In this Letter we report the CO abundance relative to H2 derived toward the circumstellar disk of the T-Tauri star TW Hya from the HD (1 - 0) and C18O (2 - 1) emission lines. The HD (1 - 0) line was observed by the Herschel Space Observatory Photodetector Array Camera and Spectrometer whereas C18O (2 - 1) observati…
HerMES: Candidate Gravitationally Lensed Galaxies and Lensing Statistics at Submillimeter Wavelengths
Aussel, H.; Pérez-Fournon, I.; Ivison, R. J. +83 more
We present a list of 13 candidate gravitationally lensed submillimeter galaxies (SMGs) from 95 deg2 of the Herschel Multi-tiered Extragalactic Survey, a surface density of 0.14 ± 0.04 deg-2. The selected sources have 500 µm flux densities (S 500) greater than 100 mJy. Gravitational lensing is confirmed by fol…
Groundwater activity on Mars and implications for a deep biosphere
Michalski, Joseph R.; Niles, Paul B.; Cuadros, Javier +3 more
By the time eukaryotic life or photosynthesis evolved on Earth, the martian surface had become extremely inhospitable, but the subsurface of Mars could potentially have contained a vast microbial biosphere. Crustal fluids may have welled up from the subsurface to alter and cement surface sediments, potentially preserving clues to subsurface habita…