Search Publications
ιHorologi, the first coronal activity cycle in a young solar-like star
Sanz-Forcada, J.; Stelzer, B.; Metcalfe, T. S.
Context. The shortest chromospheric (Ca ii H&K) activity cycle (1.6 yr) has been recently discovered in the young (~600 Myr) solar-like star ι Hor. Coronal X-ray activity cycles have only been discovered in a few stars other than the Sun, all of them with an older age and a lower activity level than ι Hor.
Aims: We intended to find the X-…
Cluster observations of ∂Bz/∂x during growth phase magnetotail stretching intervals
Petrukovich, A. A.; Nakamura, R.; Baumjohann, W. +2 more
We study a statistics of ∂Bz/∂x in a thin stretching current sheet (substorm growth phases) observed by Cluster between 8 and 18 RE downtail. After 2005, spacecraft separation allowed to measure directly this derivative of Bz along the tail axis. The near-tail events (within 14 RE) exhibited a straight d…
A near-infrared relationship for estimating black hole masses in active galactic nuclei
Peterson, Bradley M.; Elvis, Martin; Karovska, Margarita +4 more
Black hole masses for samples of active galactic nuclei (AGN) are currently estimated from single-epoch optical spectra using scaling relations anchored in reverberation mapping results. In particular, the two quantities needed for calculating black hole masses, namely the velocity and the radial distance of the orbiting gas are derived from the w…
Proper Motions and Origins of AXP 1E 2259+586 and AXP 4U 0142+61
Tendulkar, Shriharsh P.; Kulkarni, Shrinivas R.; Cameron, P. Brian
Using high-resolution NIR images supported by laser guide star adaptive optics from the Keck II telescope from 2005 to 2012, we have measured the proper motions of two anomalous X-ray pulsars, AXP 1E 2259+586 and AXP 4U 0142+61. The proper motion of AXP 1E 2259+586 in the sky frame is (µα, µδ) = (- 6.4 ± 0.6, -2.3…
Magnetic field strength distribution of magnetic bright points inferred from filtergrams and spectro-polarimetric data
Veronig, A.; Utz, D.; Hanslmeier, A. +3 more
Context. Small scale magnetic fields can be observed on the Sun in G-band filtergrams as magnetic bright points (MBPs) or identified in spectro-polarimetric measurements due to enhanced signals of Stokes profiles. These magnetic fields and their dynamics play a crucial role in understanding the coronal heating problem and also in surface dynamo mo…
Parametrized modified gravity constraints after Planck
Hu, Bin; Bartolo, Nicola; Liguori, Michele +1 more
We constrain f(R) and chameleon-type modified gravity in the framework of the Berstchinger-Zukin parametrization using the recently released Planck data, including both the cosmic mircowave background radiation (CMB) temperature power spectrum and the lensing potential power spectrum. Some other external data sets are included, such as baryon acou…
H-ATLAS: The Cosmic Abundance of Dust from the Far-infrared Background Power Spectrum
Clements, D. L.; Scott, D.; Ibar, E. +22 more
We present a measurement of the angular power spectrum of the cosmic far-infrared background (CFIRB) anisotropies in one of the extragalactic fields of the Herschel Astrophysical Terahertz Large Area Survey at 250, 350, and 500 µm bands. Consistent with recent measurements of the CFIRB power spectrum in Herschel-SPIRE maps, we confirm the ex…
Constraining the bright-end of the UV luminosity function for z ≈ 7-9 galaxies: results from CANDELS/GOODS-South
Wilkins, Stephen M.; Bunker, Andrew J.; Caruana, Joseph +3 more
The recent Hubble Space Telescope near-infrared imaging with the Wide-Field Camera #3 (WFC 3) of the Great Observatories Origins Deep Survey South (GOODS-S) field in the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) programme covering nearly 100 arcmin2, along with already existing Advanced Camera for Surveys …
The Inner Kiloparsec of Mrk 273 with Keck Adaptive Optics
Kewley, Lisa; Armus, Lee; U, Vivian +6 more
There is X-ray, optical, and mid-infrared imaging and spectroscopic evidence that the late-stage ultraluminous infrared galaxy merger Mrk 273 hosts a powerful active galactic nucleus (AGN). However, the exact location of the AGN and the nature of the nucleus have been difficult to determine due to dust obscuration and the limited wavelength covera…
Probing the role of polycyclic aromatic hydrocarbons in the photoelectric heating within photodissociation regions
Teyssier, D.; Ossenkopf, V.; Goicoechea, J. R. +8 more
Aims: We observationally investigate the relation between the photoelectric heating efficiency in photodissociation regions (PDRs) and the charge of polycyclic aromatic hydrocarbons (PAHs), which are considered to play a key role in photoelectric heating.
Methods: Using PACS onboard Herschel, we observed six PDRs spanning a wide range of…