ORCID Profile
0000-0002-9880-5039
Current Organisations
University of Rijeka
,
Institut de Física d'Altes Energies
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Publisher: American Astronomical Society
Date: 17-08-2010
Publisher: American Astronomical Society
Date: 16-02-2011
Publisher: American Astronomical Society
Date: 16-08-2011
Publisher: American Astronomical Society
Date: 19-10-2009
Publisher: American Astronomical Society
Date: 02-02-2010
Publisher: American Astronomical Society
Date: 07-04-2014
Publisher: American Astronomical Society
Date: 16-10-2015
Publisher: American Astronomical Society
Date: 11-2013
Publisher: American Astronomical Society
Date: 13-08-2012
Publisher: American Astronomical Society
Date: 02-2012
Publisher: American Astronomical Society
Date: 30-05-2012
Publisher: American Astronomical Society
Date: 06-03-2018
Publisher: EDP Sciences
Date: 27-04-2011
Publisher: American Astronomical Society
Date: 12-11-2013
Publisher: American Association for the Advancement of Science (AAAS)
Date: 28-11-2014
Abstract: Supermassive black holes with masses of millions to billions of solar masses are commonly found in the centers of galaxies. Astronomers seek to image jet formation using radio interferometry but still suffer from insufficient angular resolution. An alternative method to resolve small structures is to measure the time variability of their emission. Here we report on gamma-ray observations of the radio galaxy IC 310 obtained with the MAGIC (Major Atmospheric Gamma-ray Imaging Cherenkov) telescopes, revealing variability with doubling time scales faster than 4.8 min. Causality constrains the size of the emission region to be smaller than 20% of the gravitational radius of its central black hole. We suggest that the emission is associated with pulsar-like particle acceleration by the electric field across a magnetospheric gap at the base of the radio jet.
Publisher: EDP Sciences
Date: 04-03-2008
Publisher: American Astronomical Society
Date: 20-10-2016
Publisher: American Astronomical Society
Date: 20-06-2011
Publisher: American Astronomical Society
Date: 28-04-2015
Publisher: American Astronomical Society
Date: 06-07-2012
Publisher: EDP Sciences
Date: 07-2010
Publisher: Oxford University Press (OUP)
Date: 21-08-2009
Publisher: American Astronomical Society
Date: 31-07-2012
Publisher: American Astronomical Society
Date: 27-04-2015
Publisher: EDP Sciences
Date: 12-04-2011
Publisher: Oxford University Press (OUP)
Date: 02-07-2012
Publisher: American Astronomical Society
Date: 27-01-2014
Publisher: EDP Sciences
Date: 26-11-2010
Publisher: EDP Sciences
Date: 08-10-2009
Publisher: IOP Publishing
Date: 29-06-2011
Publisher: Springer Science and Business Media LLC
Date: 2006
DOI: 10.1038/NATURE04441
Abstract: In the favoured core-accretion model of formation of planetary systems, solid planetesimals accumulate to build up planetary cores, which then accrete nebular gas if they are sufficiently massive. Around M-dwarf stars (the most common stars in our Galaxy), this model favours the formation of Earth-mass (M(o)) to Neptune-mass planets with orbital radii of 1 to 10 astronomical units (au), which is consistent with the small number of gas giant planets known to orbit M-dwarf host stars. More than 170 extrasolar planets have been discovered with a wide range of masses and orbital periods, but planets of Neptune's mass or less have not hitherto been detected at separations of more than 0.15 au from normal stars. Here we report the discovery of a 5.5(+5.5)(-2.7) M(o) planetary companion at a separation of 2.6+1.5-0.6 au from a 0.22+0.21-0.11 M(o) M-dwarf star, where M(o) refers to a solar mass. (We propose to name it OGLE-2005-BLG-390Lb, indicating a planetary mass companion to the lens star of the microlensing event.) The mass is lower than that of GJ876d (ref. 5), although the error bars overlap. Our detection suggests that such cool, sub-Neptune-mass planets may be more common than gas giant planets, as predicted by the core accretion theory.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 11-07-2018
Abstract: Previous detections of in idual astrophysical sources of neutrinos are limited to the Sun and the supernova 1987A, whereas the origins of the diffuse flux of high-energy cosmic neutrinos remain unidentified. On 22 September 2017, we detected a high-energy neutrino, IceCube-170922A, with an energy of ~290 tera-electron volts. Its arrival direction was consistent with the location of a known γ-ray blazar, TXS 0506+056, observed to be in a flaring state. An extensive multiwavelength c aign followed, ranging from radio frequencies to γ-rays. These observations characterize the variability and energetics of the blazar and include the detection of TXS 0506+056 in very-high-energy γ-rays. This observation of a neutrino in spatial coincidence with a γ-ray-emitting blazar during an active phase suggests that blazars may be a source of high-energy neutrinos.
Publisher: Wiley
Date: 2009
Publisher: Springer Science and Business Media LLC
Date: 11-2003
DOI: 10.1038/NATURE10684
Abstract: Most known extrasolar planets (exoplanets) have been discovered using the radial velocity or transit methods. Both are biased towards planets that are relatively close to their parent stars, and studies find that around 17-30% (refs 4, 5) of solar-like stars host a planet. Gravitational microlensing, on the other hand, probes planets that are further away from their stars. Recently, a population of planets that are unbound or very far from their stars was discovered by microlensing. These planets are at least as numerous as the stars in the Milky Way. Here we report a statistical analysis of microlensing data (gathered in 2002-07) that reveals the fraction of bound planets 0.5-10 AU (Sun-Earth distance) from their stars. We find that 17(+6)(-9)% of stars host Jupiter-mass planets (0.3-10 M(J), where M(J) = 318 M(⊕) and M(⊕) is Earth's mass). Cool Neptunes (10-30 M(⊕)) and super-Earths (5-10 M(⊕)) are even more common: their respective abundances per star are 52(+22)(-29)% and 62(+35)(-37)%. We conclude that stars are orbited by planets as a rule, rather than the exception.
Publisher: EDP Sciences
Date: 04-2018
DOI: 10.1051/0004-6361/201731169
Abstract: Context. The large jet kinetic power and non-thermal processes occurring in the microquasar SS 433 make this source a good candidate for a very high-energy (VHE) gamma-ray emitter. Gamma-ray fluxes above the sensitivity limits of current Cherenkov telescopes have been predicted for both the central X-ray binary system and the interaction regions of SS 433 jets with the surrounding W50 nebula. Non-thermal emission at lower energies has been previously reported, indicating that efficient particle acceleration is taking place in the system. Aim. We explore the capability of SS 433 to emit VHE gamma rays during periods in which the expected flux attenuation due to periodic eclipses ( P orb ~ 13.1 days) and precession of the circumstellar disk ( P pre ~ 162 days) periodically covering the central binary system is expected to be at its minimum. The eastern and western SS 433/W50 interaction regions are also examined using the whole data set available. We aim to constrain some theoretical models previously developed for this system with our observations. Methods. We made use of dedicated observations from the Major Atmospheric Gamma Imaging Cherenkov telescopes (MAGIC) and High Energy Spectroscopic System (H.E.S.S.) of SS 433 taken from 2006 to 2011. These observation were combined for the first time and accounted for a total effective observation time of 16.5 h, which were scheduled considering the expected phases of minimum absorption of the putative VHE emission. Gamma-ray attenuation does not affect the jet/medium interaction regions. In this case, the analysis of a larger data set amounting to ~40–80 h, depending on the region, was employed. Results. No evidence of VHE gamma-ray emission either from the central binary system or from the eastern/western interaction regions was found. Upper limits were computed for the combined data set. Differential fluxes from the central system are found to be ≲ 10 −12 –10 −13 TeV −1 cm −2 s −1 in an energy interval ranging from ~few × 100 GeV to ~few TeV. Integral flux limits down to ~ 10 −12 –10 −13 ph cm −2 s −1 and ~ 10 −13 –10 −14 ph cm −2 s −1 are obtainedat 300 and 800 GeV, respectively. Our results are used to place constraints on the particle acceleration fraction at the inner jetregions and on the physics of the jet/medium interactions. Conclusions. Our findings suggest that the fraction of the jet kinetic power that is transferred to relativistic protons must be relatively small in SS 433, q p ≤ 2.5 × 10 −5 , to explain the lack of TeV and neutrino emission from the central system. At the SS 433/W50 interface, the presence of magnetic fields ≳10 μ G is derived assuming a synchrotron origin for the observed X-ray emission. This also implies the presence of high-energy electrons with E e − up to 50 TeV, preventing an efficient production of gamma-ray fluxes in these interaction regions.
Publisher: EDP Sciences
Date: 25-10-2012
Publisher: American Astronomical Society
Date: 12-10-2011
Publisher: EDP Sciences
Date: 12-09-2006
Publisher: American Astronomical Society
Date: 23-04-2013
Publisher: Elsevier BV
Date: 08-2018
Publisher: American Astronomical Society
Date: 14-11-2012
Publisher: EDP Sciences
Date: 27-03-2013
Publisher: American Astronomical Society
Date: 27-11-2013
Publisher: EDP Sciences
Date: 08-2015
Publisher: American Astronomical Society
Date: 17-01-2013
Publisher: American Astronomical Society
Date: 06-05-2013
Publisher: Oxford University Press (OUP)
Date: 11-05-2009
Publisher: EDP Sciences
Date: 13-05-2005
Publisher: American Astronomical Society
Date: 07-2022
Abstract: We report the first unambiguous detection and mass measurement of an isolated stellar-mass black hole (BH). We used the Hubble Space Telescope (HST) to carry out precise astrometry of the source star of the long-duration ( t E ≃ 270 days), high-magnification microlensing event MOA-2011-BLG-191/OGLE-2011-BLG-0462 (hereafter designated as MOA-11-191/OGLE-11-462), in the direction of the Galactic bulge. HST imaging, conducted at eight epochs over an interval of 6 yr, reveals a clear relativistic astrometric deflection of the background star’s apparent position. Ground-based photometry of MOA-11-191/OGLE-11-462 shows a parallactic signature of the effect of Earth’s motion on the microlensing light curve. Combining the HST astrometry with the ground-based light curve and the derived parallax, we obtain a lens mass of 7.1 ± 1.3 M ⊙ and a distance of 1.58 ± 0.18 kpc. We show that the lens emits no detectable light, which, along with having a mass higher than is possible for a white dwarf or neutron star, confirms its BH nature. Our analysis also provides an absolute proper motion for the BH. The proper motion is offset from the mean motion of Galactic disk stars at similar distances by an amount corresponding to a transverse space velocity of ∼45 km s −1 , suggesting that the BH received a “natal kick” from its supernova explosion. Previous mass determinations for stellar-mass BHs have come from radial velocity measurements of Galactic X-ray binaries and from gravitational radiation emitted by merging BHs in binary systems in external galaxies. Our mass measurement is the first for an isolated stellar-mass BH using any technique.
Publisher: American Astronomical Society
Date: 02-05-2012
Publisher: American Astronomical Society
Date: 07-04-2009
Publisher: American Astronomical Society
Date: 14-10-2010
Publisher: American Astronomical Society
Date: 08-01-2013
No related grants have been discovered for Dijana Dominis Prester.