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Investigating the X-ray counterparts to unidentified sources in the 1000-orbit INTEGRAL/IBIS catalogue
Bird, A. J.; Fiocchi, M.; Ubertini, P. +6 more
The latest INTEGRAL/IBIS all-sky survey lists 219 hard X-ray sources whose nature is still unknown. We report on our ongoing campaign aimed at identifying these high-energy emitters by exploiting the focusing capabilities of the X-ray Telescope (XRT, 0.2-10 keV) onboard Swift, which allow an enhancement of the source localization to arcsec level, …
The Prototypical Young L/T-Transition Dwarf HD 203030B Likely Has Planetary Mass
Metchev, Stanimir; Miles-Páez, Paulo A.; Marengo, Massimo +2 more
Upon its discovery in 2006, the young L7.5 companion to the solar analog HD 203030 was found to be ≈ 200 K cooler than older late-L dwarfs, which is quite unusual. HD 203030B offered the first clear indication that the effective temperature at the L-to-T spectral type transition depends on surface gravity: now a well-known characteristic of low-gr…
The Araucaria Project: The Distance to the Fornax Dwarf Galaxy from Near-infrared Photometry of RR Lyrae Stars
Gieren, Wolfgang; Pietrzyński, Grzegorz; Górski, Marek +2 more
We have obtained single-phase near-infrared (NIR) magnitudes in the J and K bands for 77 RR Lyrae (RRL) stars in the Fornax Dwarf Spheroidal Galaxy. We have used different theoretical and empirical NIR period-luminosity-metallicity calibrations for RRL stars to derive their absolute magnitudes, and found a true, reddening-corrected distance modulu…
Consistency of Hitomi, XMM-Newton, and Chandra 3.5 keV data from Perseus
Conlon, Joseph P.; Day, Francesca; Jennings, Nicholas +2 more
Hitomi observations of Perseus with the Soft X-ray Spectrometer (SXS) provide a high-resolution look at the 3.5 keV feature reported by multiple groups in the Perseus cluster. The Hitomi spectrum—which involves the sum of diffuse cluster emission and the pointlike central active galactic nucleus (AGN)—does not show any excess at E ∼3.5 keV , givin…
CMB anomalies and the effects of local features of the inflaton potential
Gariazzo, Stefano; Cadavid, Alexander Gallego; Romano, Antonio Enea
Recent analysis of the WMAP and Planck data have shown the presence of a dip and a bump in the spectrum of primordial perturbations at the scales
An Active Galactic Nucleus Caught in the Act of Turning Off and On
Greene, Jenny E.; Stern, Daniel; Comerford, Julia M. +5 more
We present the discovery of an active galactic nucleus (AGN) that is turning off and then on again in the z = 0.06 galaxy SDSS J1354+1327. This episodic nuclear activity is the result of discrete accretion events that could have been triggered by a past interaction with the companion galaxy that is currently located 12.5 kpc away. We originally ta…
Are Internetwork Magnetic Fields in the Solar Photosphere Horizontal or Vertical?
Lites, B. W.; Borrero, J. M.; Danilovic, S. +1 more
Using many observations obtained during 2007 with the Spectro-Polarimeter of the Hinode Solar Optical Telescope, we explore the angular distribution of magnetic fields in the quiet internetwork regions of the solar photosphere. Our work follows from the insight of Stenflo, who examined only linear polarization signals in photospheric lines, thereb…
KELT-18b: Puffy Planet, Hot Host, Probably Perturbed
Bieryla, Allyson; Latham, David W.; Berlind, Perry +54 more
We report the discovery of KELT-18b, a transiting hot Jupiter in a 2.87-day orbit around the bright (V = 10.1), hot, F4V star BD+60 1538 (TYC 3865-1173-1). We present follow-up photometry, spectroscopy, and adaptive optics imaging that allow a detailed characterization of the system. Our preferred model fits yield a host stellar temperature of 667…
Mars Under Primordial Solar Wind Conditions: Mars Express Observations of the Strongest CME Detected at Mars Under Solar Cycle #24 and its Impact on Atmospheric Ion Escape
Barabash, Stas; Nilsson, Hans; Holmström, Mats +3 more
An extremely strong Coronal Mass Ejection (CME) impacted Mars on 12 July 2011, while the Mars Express spacecraft was present inside the nightside ionosphere. Estimated solar wind density and speed during the event are 39 particles cm-3 and 730 km/s, corresponding to nominal solar wind flux at Mars when the solar system was ∼1.1 Ga old. …
X-ray flaring in PDS 456 observed in a high-flux state
Turner, T. J.; Reeves, J. N.; Braito, V. +3 more
We present an analysis of a 190 ks (net exposure) Suzaku observation, carried out in 2007, of the nearby (z = 0.184) luminous (Lbol ∼ 1047 erg s-1) quasar PDS 456. In this observation, the intrinsically steep bare continuum is revealed compared to subsequent observations, carried out in 2011 and 2013, where the sou…