Search Publications
Was the soft X-ray flare in NGC 3599 due to an AGN disc instability or a delayed tidal disruption event?
Read, A. M.; Komossa, S.; Motta, S. E. +1 more
We present unpublished data from a tidal disruption candidate in NGC 3599 which show that the galaxy was already X-ray bright 18 months before the measurement which led to its classification. This removes the possibility that the flare was caused by a classical, fast-rising, short-peaked, tidal disruption event. Recent relativistic simulations ind…
Constraints on µ-distortion fluctuations and primordial non-Gaussianity from Planck data
Khatri, Rishi; Sunyaev, Rashid
We use the Planck HFI channel maps to make an all sky map of µ-distortion fluctuations. Our µ-type distortion map is dominated by the y-type distortion contamination from the hot gas in the low redshift Universe and we can thus only place upper limits on the µ-type distortion fluctuations. For the amplitude of µ-type distor…
Venus's major cloud feature as an equatorially trapped wave distorted by the wind
Sánchez-Lavega, A.; López-Valverde, M. A.; Machado, P. +2 more
The superrotation of the atmospheres of slowly rotating bodies is a long-standing problem yet unsolved in atmospheric dynamics. On Venus, the most extreme case known of superrotation, this is accompanied and influenced by a recurrent planetary-scale cloud structure, known as the Y feature. So far, no model has simultaneously reproduced its shape, …
The role of the Fraunhofer lines in solar brightness variability
Solanki, S. K.; Shapiro, A. I.; Tagirov, R. V. +2 more
Context. The solar brightness varies on timescales from minutes to decades. A clear identification of the physical processes behind such variations is needed for developing and improving physics-based models of solar brightness variability and reconstructing solar brightness in the past. This is, in turn, important for better understanding the sol…
Hyperbolic inflation in the light of Planck 2015 data
Basilakos, Spyros; Barrow, John D.
Rubano and Barrow have discussed the emergence of a dark energy, with late-time cosmic acceleration arising from a self-interacting homogeneous scalar field with a potential of hyperbolic power type. Here, we study the evolution of this scalar-field potential back in the inflationary era. Using the hyperbolic power potential in the framework of in…
Variability-selected active galactic nuclei in the VST-SUDARE/VOICE survey of the COSMOS field
Salvato, M.; Brandt, W. N.; Vaccari, M. +16 more
Context. Active galaxies are characterized by variability at every wavelength, with timescales from hours to years depending on the observing window. Optical variability has proven to be an effective way of detecting AGNs in imaging surveys, lasting from weeks to years.
Aims: In the present work we test the use of optical variability as a too…
SXP 5.05 = IGR J00569-7226: using X-rays to explore the structure of a Be star's circumstellar disc
Haberl, F.; Udalski, A.; Bartlett, E. S. +5 more
On MJD 56590-1 (2013 Oct 25-26), observations of the Magellanic Clouds by the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) observatory discovered a previously unreported bright, flaring X-ray source. This source was initially given the identification IGR J00569-7226. Subsequent multiwavelength observations identified the system as ne…
Post-Planck dark energy constraints
Hazra, Dhiraj Kumar; Pal, Supratik; Sen, Anjan A. +2 more
We constrain plausible dark energy models using the recently published cosmic microwave background (CMB) temperature anisotropy data from Planck together with WMAP9 low-ℓ polarization data and the data from low redshift surveys. To circumvent the limitations of any particular equation of state toward describing all existing dark energy models, we …
Total electron content in the Martian atmosphere: A critical assessment of the Mars Express MARSIS data sets
Gurnett, D. A.; Lester, M.; Morgan, D. D. +14 more
The total electron content (TEC) is one of the most useful parameters to evaluate the behavior of the Martian ionosphere because it contains information on the total amount of free electrons, the main component of the Martian ionospheric plasma. The Mars Express Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) radar is able to d…
Charge exchange in cometary coma: Discovery of H- ions in the solar wind close to comet 67P/Churyumov-Gerasimenko
Goldstein, R.; Mokashi, P.; Tzou, C. -Y. +4 more
As Rosetta was orbiting comet 67P/Churyumov-Gerasimenko, the Ion and Electron Sensor detected negative particles with angular distributions like those of the concurrently measured solar wind protons but with fluxes of only about 10% of the proton fluxes and energies of about 90% of the proton energies. Using well-known cross sections and energy-lo…