Papers by Lindita Hamolli
The Sixteenth Marcel Grossmann Meeting
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Galaxies
In this work, we investigate the possibility of observing quasars, particularly lensed quasars, b... more In this work, we investigate the possibility of observing quasars, particularly lensed quasars, by the Nancy Grace Roman Space Telescope (Roman). To this aim, based on the capabilities of the Roman Space Telescope and the results from the quasar luminosity function (QLF) in the infrared band of the Spitzer Space Telescope imaging survey, we calculated the number of quasars expected to be in its field of view. In order to estimate the number of lensed quasars, we develop a Monte Carlo simulation to estimate the probability that a quasar is lensed once or more times by foreground galaxies. Using the mass–luminosity distribution function of galaxies and the redshift distributions of galaxies and quasars, we find that 1 per 180 observed quasars will be lensed by foreground galaxies. Further on, adopting a singular isothermal sphere (SIS) model for lens galaxies, we calculate the time delay between lensed images for single and multiple lensing systems and present their distributions. We ...
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Astrophysics and Space Science, 2018
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Astrophysical Bulletin, 2017
The K2’s Campaign 9 (K2C9) by the Kepler satellite for microlensing observations towards the Gala... more The K2’s Campaign 9 (K2C9) by the Kepler satellite for microlensing observations towards the Galactic bulge started on April 7, 2016, and is going to last for about three months. It offers the first chance to measure the masses of members of the large population of the isolated dark low-mass objects further away in our Galaxy, free-floating planets (FFPs). Intentionally, this observational period of K2 will overlap with that of the 2016 Spitzer follow-up microlensing project expected to start in June, 2016. Therefore, for the first time it is going to be possible to observe simultaneously the same microlensing events from a ground-based telescope and two satellites. This will help in removing the two-fold degeneracy of the impact parameter and in estimating the FFP mass, provided that the angular Einstein ring radius ΘE is measured. In this paper we calculate the probability that a microlensing event is detectable by two or more telescopes and study how it depends on the mass function index of FFPs and the position of the observers on the orbit.
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International Conference on Recent Trends and Applications in Computer Science and Information Technology, 2016
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In recent years free-floating planets (FFPs) have drawn a great interest among astrophysicists. G... more In recent years free-floating planets (FFPs) have drawn a great interest among astrophysicists. Gravitational microlensing is a unique and exclusive method for their investigation which may allow obtaining precious information about their mass and spatial distribution. The planned Euclid space-based observatory will be able to detect a substantial number of microlensing events caused by FFPs towards the Galactic bulge. Making use of a synthetic population algorithm, we investigate the possibility of detecting finite source effects in simulated microlensing events due to FFPs. We find a significant efficiency for finite source effect detection that turns out to be between 20% and 40% for a FFP power law mass function index in the range [0.9, 1.6]. For many of such events it will also be possible to measure the angular Einstein radius and therefore constrain the lens physical parameters. These kinds of observations will also offer a unique possibility to investigate the photosphere an...
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Free-floating planets are recently drawing a special interest among the scientific community. Gra... more Free-floating planets are recently drawing a special interest among the scientific community. Gravitational microlensing is up to now the exclusive method for the study of this Galactic population. In this work we find that the future Euclid space-based observatory can discover a substantial number of microlensing events in its field of view, caused by freefloating planets. Making use of a synthetic population, we investigate also the importance of using the parallax effect as an additional source of information. We conclude about the best positions of the Earth in its orbit for obtaining the greatest number of events with parallax traces.
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The multi-messenger astronomy: gamma-ray bursts, search for electromagnetic counterparts to neutrino events and gravitational waves. Proceedings of the International Conference., 2019
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The isolated dark low-mass objects in our Galaxy, such as free-floating planets (FFP), can be det... more The isolated dark low-mass objects in our Galaxy, such as free-floating planets (FFP), can be detected by microlensing observations. By the light curve can be defined three parameters, but only the Einstein time, TE involves the mass, the distance and the transverse velocity of the lens. To break this degeneracy, have to be detected the perturbations in the light curve due to the relative accelerations among the observer, the lens and the source. Recently, toward Galactic bulge are planned space-based microlensing observations by WFIRST, which can be located in L2 point or geosynchronous orbit (GSO). Using the simulations Monte Carlo in C++ we investigate that the better position for the parallax e ffect detection in microlensing events caused by FFPs is L2 point than GSO.
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THESEUS is an ESA space based project, which aims to explore the early universe by unveiling a co... more THESEUS is an ESA space based project, which aims to explore the early universe by unveiling a complete census of Gamma-ray Burst (GRB) population in the first billion years. This goal is expected to be realized by the combined observations of its three instruments on board: the Soft X-ray Imager (SXI), the X and Gamma Imaging Spectrometer (XGIS), and the InfraRed Telescope (IRT). This last one will identify, localise, and study the afterglow of the GRBs detected by SXI and XGIS, and about 40% of its time will be devoted to an all-sky photometric survey, which will certainly detect a relevant number of extragalactic sources, including Quasars. In this paper, we focus on the capability of IRT-THESEUS Telescope to observe Quasars and, in particular, Quasars lensed by foreground galaxies. In our analysis we consider the recent results for the Quasar Luminosity Function (QLF) in the infrared band based on the Spitzer Space Telescope imaging survey. In order to estimate the number of len...
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Journal of Physics: Conference Series, Mar 14, 2012
In this work we examine the possibility of observing microlensing events in the Kepler space obse... more In this work we examine the possibility of observing microlensing events in the Kepler space observatory field of view, caused by brown dwarfs or free-floating planets. We calculate the optical depth towards the field of view of the Kepler satellite and the rate of these events based on latest results about mass distribution of astrophysical objects from brown dwarf down to Earth mass order. With the current data, the probability of such events is insignificant, due to the small number of stars observed by this instrument compared to other experiments devoted to the microlensing method. Nevertheless, this probability may increase significantly in the case of a higher presence of free-floating planets, whose number is poorly defined so far.
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Arabian Journal of Mathematics
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Astrophysics and Space Science
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Astrophysics and Space Science, 2016
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International Journal of Modern Physics D, 2013
ABSTRACT Free-floating planets (FFPs) are recently drawing a special interest of the scientific c... more ABSTRACT Free-floating planets (FFPs) are recently drawing a special interest of the scientific community. Gravitational microlensing is up to now the exclusive method for the investigation of FFPs, including their spatial distribution function and mass function. In this paper, we examine the possibility that the future Euclid space-based observatory may allow to discover a substantial number of microlensing events caused by FFPs. Based on latest results about the free-floating planet (FFP) mass function in the mass range [10-5, 10-2]M⊙, we calculate the optical depth towards the Galactic bulge as well as the expected microlensing rate and find that Euclid may be able to detect hundreds to thousands of these events per month. Making use of a synthetic population, we also investigate the possibility of detecting parallax effect in simulated microlensing events due to FFPs and find a significant efficiency for the parallax detection that turns out to be around 30%.
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The Thirteenth Marcel Grossmann Meeting, 2014
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Advances in Astronomy, 2015
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Papers by Lindita Hamolli