Search Publications
A Long-Term Study of Ultraluminous X-ray Sources in NGC 891
Earley, Nicholas M.; Dwarkadas, Vikram V.; Cirillo, Victoria
We perform empirical fits to the Chandra and XMM-Newton spectra of three ultraluminous X-ray sources (ULXs) in the edge-on spiral galaxy NGC 891, monitoring the region over a 17-year time window. One of these sources was visible since the early 1990s with ROSAT and was observed multiple times with Chandra and XMM-Newton. Another was visible since …
Searching for Gamma-Ray Binaries in Multiwavelength Catalogs
Luque-Escamilla, Pedro L.; Martí, Josep
The number of gamma-ray binaries currently known is still so small that even a new finding represents a significant expansion of its population. We present a possible hunting strategy based on screening different catalogs to filter potential peculiar stars consistent with gamma-ray sources whose association at lower energies is not yet certain. So…
INTEGRAL View of TeV Sources: A Legacy for the CTA Project
Ubertini, Pietro; Bazzano, Angela; Bird, Antony J. +7 more
Investigations that were carried out over the last two decades with novel and more sensitive instrumentation have dramatically improved our knowledge of the more violent physical processes taking place in galactic and extra-galactic Black-Holes, Neutron Stars, Supernova Remnants/Pulsar Wind Nebulae, and other regions of the Universe where relativi…
In the Quest for Cosmic Rotation
Korotky, Vladimir A.; Masár, Eduard; Obukhov, Yuri N.
This paper analyzes the problem of global rotation in general relativity (GR) theory. Simple cosmological models with rotation and expansion are presented, which give a natural explanation of the modern values of the acceleration parameter at different red shifts without involving the concepts of "dark energy" and "dark matter". It is shown that d…
Modified Newtonian Gravity, Wide Binaries and the Tully-Fisher Relation
Acedo, Luis
A recent study of a sample of wide binary star systems from the Hipparcos and Gaia catalogues has found clear evidence of a gravitational anomaly of the same kind as that appearing in galaxies and galactic clusters. Instead of a relative orbital velocity decaying as the square root of the separation, ΔV∝r‑1/2, it was shown that an asymptotic const…
A Test of Gravitational Theories Including Torsion with the BepiColombo Radio Science Experiment
Schettino, Giulia; Serra, Daniele; Tommei, Giacomo +1 more
Within the framework of the relativity experiment of the ESA/JAXA BepiColombo mission to Mercury, which was launched at the end of 2018, we describe how a test of alternative theories of gravity, including torsion can be set up. Following March et al. (2011), the effects of a non-vanishing spacetime torsion have been parameterized by three torsion…
New Constraints on Spatial Variations of the Fine Structure Constant from Clusters of Galaxies
Ebeling, Harald; Kocevski, Dale; Martins, Carlos J. A. P. +1 more
We have constrained the spatial variation of the fine structure constant using multi-frequency measurements of the thermal Sunyaev-Zeldovich effect of 618 X-ray selected clusters. Although our results are not competitive with the ones from quasar absorption lines, we improved by a factor 10 and ∼2.5 previous results from Cosmic Microwave Backgroun…