0000000000673071
AUTHOR
E. Ambrosi
showing 4 related works from this author
The Chameleon on the branches: spectral state transition and dips in NGC 247 ULX-1
2021
Soft Ultra-Luminous X-ray (ULXs) sources are a subclass of the ULXs that can switch from a supersoft spectral state, where most of the luminosity is emitted below 1 keV, to a soft spectral state with significant emission above 1 keV. In a few systems, dips have been observed. The mechanism behind this state transition and the dips nature are still debated. To investigate these issues, we obtained a long XMM-Newton monitoring campaign of a member of this class, NGC 247 ULX-1. We computed the hardness-intensity diagram for the whole dataset and identified two different branches: the normal branch and the dipping branch, which we study with four and three hardness-intensity resolved spectra, r…
Time domain astronomy with the THESEUS satellite
2021
THESEUS is a medium size space mission of the European Space Agency, currently under evaluation for a possible launch in 2032. Its main objectives are to investigate the early Universe through the observation of gamma-ray bursts and to study the gravitational waves electromagnetic counterparts and neutrino events. On the other hand, its instruments, which include a wide field of view X-ray (0.3-5 keV) telescope based on lobster-eye focussing optics and a gamma-ray spectrometer with imaging capabilities in the 2-150 keV range, are also ideal for carrying out unprecedented studies in time domain astrophysics. In addition, the presence onboard of a 70 cm near infrared telescope will allow simu…
Quasi-periodic dipping in the ultraluminous X-ray source, NGC 247 ULX-1
2021
Most ultraluminous X-ray sources (ULXs) are believed to be stellar mass black holes or neutron stars accreting beyond the Eddington limit. Determining the nature of the compact object and the accretion mode from broadband spectroscopy is currently a challenge, but the observed timing properties provide insight into the compact object and details of the geometry and accretion processes. Here we report a timing analysis for an 800 ks XMM-Newton campaign on the supersoft ultraluminous X-ray source, NGC 247 ULX-1. Deep and frequent dips occur in the X-ray light curve, with the amplitude increasing with increasing energy band. Power spectra and coherence analysis reveals the dipping preferential…
How radical prostatectomy procedures have changed over the last 10 years in Italy: a comparative analysis based on more than 1500 patients participat…
2020
Purpose Therapeutic strategies for prostate cancer (PCa) have been evolving dramatically worldwide. The current article reports on the evolution of surgical management strategies for PCa in Italy. Methods The data from two independent Italian multicenter projects, the MIRROR-SIU/LUNA (started in 2007, holding data of 890 patients) and the Pros-IT-CNR project (started in 2014, with data of 692 patients), were compared. Differences in patients' characteristics were evaluated. Multivariable logistic regression models were used to identify characteristics associated with robot-assisted (RA) procedure, nerve sparing (NS) approach, and lymph node dissection (LND). Results The two cohorts did not …