Search Publications
Constraints on the early and late integrated Sachs-Wolfe effects from the Planck 2015 cosmic microwave background anisotropies in the angular power spectra
Melchiorri, Alessandro; Cabass, Giovanni; Gerbino, Martina +3 more
The integrated Sachs-Wolfe (ISW) effect predicts additional anisotropies in the cosmic microwave background (CMB) due to time variation of the gravitational potential when the expansion of the Universe is not matter dominated. The ISW effect is therefore expected in the early Universe, due to the presence of relativistic particles at recombination…
Searching for coherent pulsations in ultraluminous X-ray sources
Santangelo, A.; Ducci, L.; Doroshenko, V.
Luminosities of ultraluminous X-ray sources (ULXs) are uncomfortably large when compared to the Eddington limit for isotropic accretion onto stellar-mass object. Most often either supercritical accretion onto stellar mass black holes or accretion onto intermediate mass black holes is invoked the high luminosities of ULXs. However, the recent disco…
Ground-based Paα Narrow-band Imaging of Local Luminous Infrared Galaxies. I. Star Formation Rates and Surface Densities
Tamura, Yoichi; Kohno, Kotaro; Tanabé, Toshihiko +33 more
Luminous infrared galaxies (LIRGs) are enshrouded by a large amount of dust produced by their active star formation, and it is difficult to measure their activity in optical wavelengths. We have carried out Paα narrow-band imaging observations of 38 nearby star forming galaxies including 33 LIRGs listed in the IRAS Revised Bright Galaxy Sample cat…
Surfing gravitational waves: can bigravity survive growing tensor modes?
Amendola, Luca; Pettorino, Valeria; Könnig, Frank +2 more
The theory of bigravity offers one of the simplest possibilities to describe a massive graviton while having self-accelerating cosmological solutions without a cosmological constant. However, it has been shown recently that bigravity is affected by early-time fast growing modes on the tensor sector. Here we argue that we can only trust the linear …
Dynamics in Sunspot Umbra as Seen in New Solar Telescope and Interface Region Imaging Spectrograph Data
Yurchyshyn, V.; Kilcik, A.; Abramenko, V.
We analyze sunspot oscillations using Interface Region Imaging Spectrograph (IRIS) slit-jaw and spectral data and narrow-band chromospheric images from the New Solar Telescope (NST) for the main sunspot in NOAA AR 11836. We report that the difference between the shock arrival times as measured by the Mg II k 2796.35 Å and Si IV 1393.76 Å line form…
Birkeland current effects on high-latitude ground magnetic field perturbations
Anderson, B. J.; Snekvik, K.; Østgaard, N. +8 more
Magnetic perturbations on ground at high latitudes are directly associated only with the divergence-free component of the height-integrated horizontal ionospheric current, J⊥,df. Here we show how J⊥,df can be expressed as the total horizontal current J⊥ minus its curl-free component, the latter being completely det…
Suzaku studies of the supernova remnant CTB 109 hosting the magnetar 1E 2259+586
Enoto, Teruaki; Makishima, Kazuo; Kaneda, Hidehiro +4 more
Ages of the magnetar 1E 2259+586 and the associated supernova remnant CTB 109 were studied. Analyzing the Suzaku data of CTB 109, its age was estimated to be ∼ 14 kyr, which is much younger than the measured characteristic age of 1E 2259+586, 230 kyr. This reconfirms the previously reported age discrepancy of this magnetar/remnant association, and…
Pseudostreamers as the Source of a Separate Class of Solar Coronal Mass Ejections
Wang, Y. -M.
Using white-light and extreme-ultraviolet imaging observations, we confirm that pseudostreamers (streamers that separate coronal holes of the same polarity) give rise to a different type of coronal mass ejection (CME) from that associated with helmet streamers (defined as separating coronal holes of opposite polarity). Whereas helmet streamers are…
A Pilot Survey for C III] Emission in the Reionization Era: Gravitationally Lensed z ∼ 7-8 Galaxies in the Frontier Fields Cluster Abell 2744
Stark, Daniel P.; Ellis, Richard S.; Belli, Sirio +1 more
We report results of a search for C iii] λ λ 1907, 1909 Å emission using Keck’s MOSFIRE spectrograph in a sample of 7 {{z}phot}∼ 7-8 candidates (H∼ 27) lensed by the Hubble Frontier Field cluster Abell 2744. Earlier work has suggested the promise of using the C iii] doublet for redshift confirmation of galaxies in the reionization era g…
Extremely Large EUV Late Phase of Solar Flares
Wang, Yuming; Shen, Chenglong; Liu, Rui +3 more
The second peak in the Fe xvi 33.5 nm line irradiance observed during solar flares by the Extreme-Ultraviolet Variability Experiment (EVE) is known as the EUV late phase. Our previous paper in 2013 by Liu et al. found that the main emissions in the late phase are originated from large-scale loop arcades that are closely connected to but different …