Search Publications
PSR J0030+0451 Mass and Radius from NICER Data and Implications for the Properties of Neutron Star Matter
Harding, A. K.; Ray, P. S.; Wood, K. S. +18 more
Neutron stars are not only of astrophysical interest, but are also of great interest to nuclear physicists because their attributes can be used to determine the properties of the dense matter in their cores. One of the most informative approaches for determining the equation of state (EoS) of this dense matter is to measure both a star’s equatoria…
Cosmological Constraints from the Hubble Diagram of Quasars at High Redshifts
Lusso, E.; Risaliti, G.
The concordance model (Λ cold dark matter (ΛCDM) model, where Λ is the cosmological constant) reproduces the main current cosmological observations1-4 assuming the validity of general relativity at all scales and epochs and the presence of CDM and of Λ, equivalent to dark energy with a constant density in space and time. However, the ΛC…
An Embedded X-Ray Source Shines through the Aspherical AT 2018cow: Revealing the Inner Workings of the Most Luminous Fast-evolving Optical Transients
Berger, E.; Hurley, K.; Götz, D. +42 more
We present the first extensive radio to γ-ray observations of a fast-rising blue optical transient, AT 2018cow, over its first ∼100 days. AT 2018cow rose over a few days to a peak luminosity L pk ∼ 4 × 1044 erg s-1, exceeding that of superluminous supernovae (SNe), before declining as L ∝ t -2. Initial s…
Nine-hour X-ray quasi-periodic eruptions from a low-mass black hole galactic nucleus
Read, A. M.; Knigge, C.; Heywood, I. +11 more
In the past two decades, high-amplitude electromagnetic outbursts have been detected from dormant galaxies and often attributed to the tidal disruption of a star by the central black hole1,2. X-ray emission from the Seyfert 2 galaxy GSN 069 (2MASX J01190869-3411305) at a redshift of z = 0.018 was first detected in July 2010 and implies …
A year in the life of GW 170817: the rise and fall of a structured jet from a binary neutron star merger
Troja, E.; Piro, L.; van Eerten, H. +6 more
We present the results of our year-long afterglow monitoring of GW 170817, the first binary neutron star merger detected by Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) and Advanced Virgo. New observations with the Australian Telescope Compact Array and the Chandra X-ray Telescope were used to constrain its late-time behavio…
Observation of inverse Compton emission from a long γ-ray burst
Maraschi, L.; Troja, E.; Piro, L. +304 more
Long-duration γ-ray bursts (GRBs) originate from ultra-relativistic jets launched from the collapsing cores of dying massive stars. They are characterized by an initial phase of bright and highly variable radiation in the kiloelectronvolt-to-megaelectronvolt band, which is probably produced within the jet and lasts from milliseconds to minutes, kn…
Universal thermodynamic properties of the intracluster medium over two decades in radius in the X-COP sample
Pointecouteau, E.; Rossetti, M.; Rasia, E. +10 more
Context. The hot plasma in a galaxy cluster is expected to be heated to high temperatures through shocks and adiabatic compression. The thermodynamical properties of the gas encode information on the processes leading to the thermalization of the gas in the cluster's potential well and on non-gravitational processes such as gas cooling, AGN feedba…
1ES 1927+654: An AGN Caught Changing Look on a Timescale of Months
Filippenko, Alexei V.; Remillard, Ronald A.; Rest, Armin +21 more
We study the sudden optical and ultraviolet (UV) brightening of 1ES 1927+654, which until now was known as a narrow-line active galactic nucleus (AGN). 1ES 1927+654 was part of the small and peculiar class of “true Type-2” AGNs that lack broad emission lines and line-of-sight obscuration. Our high-cadence spectroscopic monitoring captures the appe…
Constraining the Neutron Star Mass-Radius Relation and Dense Matter Equation of State with NICER. I. The Millisecond Pulsar X-Ray Data Set
Steiner, James F.; Remillard, Ronald A.; Enoto, Teruaki +27 more
We present the set of deep Neutron Star Interior Composition Explorer (NICER) X-ray timing observations of the nearby rotation-powered millisecond pulsars PSRs J0437-4715, J0030+0451, J1231-1411, and J2124-3358, selected as targets for constraining the mass-radius relation of neutron stars and the dense matter equation of state (EoS) via modeling …
Non-thermal pressure support in X-COP galaxy clusters
Pointecouteau, E.; Rossetti, M.; Rasia, E. +13 more
Galaxy clusters are the endpoints of structure formation and are continuously growing through the merging and accretion of smaller structures. Numerical simulations predict that a fraction of their energy content is not yet thermalized, mainly in the form of kinetic motions (turbulence, bulk motions). Measuring the level of non-thermal pressure su…