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Abstract: We present the results of our analysis of Gaia19dke, an extraordinary microlensing event in the Cygnus constellation that the Gaia satellite discovered. This event featured a strong microlensing parallax effect, resulting in multiple light curve peaks. We conducted extensive photometric, spectroscopic, and high-resolution imaging follow-up observations to determine the mass and nature of the invisible lensing object. Using the Milky Way priors on the density and proper motion of lenses, we found that the lens is likely to be located at a distance of DL=3.3(+2.1, -1.7) kpc, and has a mass of ML=0.50(+0.82, -0.27) M☉. Based on its low luminosity and mass, we propose that the lens in the Gaia19dke event is either a main sequence star or an isolated white dwarf. Due to its brightness, longevity, and lack of blending, Gaia19dke is a target for which the forthcoming Gaia Data Release 4 data will help to constrain the parameters of the lens.
Keywords: gravitational lensing, micro stars, fundamental parameters, white dwarfs, astrophysics, solar astrophysics, stellar astrophysics, astrophysics of galaxies, instrumentation for astrophysics, methods for astrophysics
Published in RUNG: 13.01.2025; Views: 201; Downloads: 1
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Abstract: In this presentation, the existing open data practices in high energy astro-, particle and astroparticle physics are presented. Open data has become fundamental in astrophysics, particle, and astroparticle physics, enhancing collaboration, reproducibility, and transparency, while accelerating innovation. A recent shift toward openness, marked by data-sharing initiatives and accessible resources, is driving breakthroughs like the multi-messenger observation of GW170817, a neutron star merger detected in both gravitational waves and gamma rays, and the identification of blazar TXS 0506+056 as a high-energy neutrino source. Across these fields, robust efforts are underway to develop and implement FAIR-compliant data policies, with a wide array of supportive tools, standards, protocols, and software already in use (Virtual Observatory in astrophysics, CERN’s Open Data Portal in particle physics, ...). The challenges of astroparticle physics data, often more complex than traditional astrophysics or particle physics data, call for additional coordination and technical advancements to meet FAIR principles effectively. Machine learning also plays a transformative role in these domains, enhancing the analysis of both proprietary and open data to reveal new insights and optimize research methodologies.
Keywords: open data, FAIR data, astrophysics, high-energy particle physics, astroparticle physics, multi-messenger astronomy
Published in RUNG: 06.01.2025; Views: 213; Downloads: 1
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Abstract: We report discovering an exoplanet from following up a microlensing event alerted by Gaia. The event Gaia22dkv is toward a disk source rather than the traditional bulge microlensing fields. Our primary analysis yields a Jovian planet with M_p = 0.59 (+0.15, -0.05) M_J at a projected orbital separation r_perpendicular = 1.4 (+0.8, -0.3) au, and the host is a ∼1.1 M⊙ turnoff star at ∼1.3 kpc. At r' ~= 14, the host is far brighter than any previously discovered microlensing planet host, opening up the opportunity to test the microlensing model with radial velocity (RV) observations. RV data can be used to measure the planet's orbital period and eccentricity, and they also enable searching for inner planets of the microlensing cold Jupiter, as expected from the "inner–outer correlation" inferred from Kepler and RV discoveries. Furthermore, we show that Gaia astrometric microlensing will not only allow precise measurements of its angular Einstein radius θ_E but also directly measure the microlens parallax vector and unambiguously break a geometric light-curve degeneracy, leading to the definitive characterization of the lens system.
Keywords: gravitational microlensing exoplanet detection, planetary astrophysics, astrophysics of galaxies, instrumentation astrophysics, methods for astrophysics, solar astrophysics, stellar astrophysics
Published in RUNG: 23.08.2024; Views: 862; Downloads: 8
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Keywords: gamma-ray astrophysics, dark matter, galactic center
Published in RUNG: 15.01.2024; Views: 1724; Downloads: 7
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Abstract: Context. The timescale of a microlensing event scales as a square root of a lens mass. Therefore, long-lasting events are important candidates for massive lenses, including black holes. Aims. Here, we present the analysis of the Gaia18cbf microlensing event reported by the Gaia Science Alerts system. It exhibited a long timescale and features that are common for the annual microlensing parallax effect. We deduce the parameters of the lens based on the derived best fitting model. Methods. We used photometric data collected by the Gaia satellite as well as the follow-up data gathered by the ground-based observatories. We investigated the range of microlensing models and used them to derive the most probable mass and distance to the lens using a Galactic model as a prior. Using a known mass-brightness relation, we determined how likely it is that the lens is a main-sequence (MS) star. Results. This event is one of the longest ever detected, with the Einstein timescale of tE = 491.41−84.94+128.31 days for the best solution and tE = 453.74−105.74+178.69 days for the second best. Assuming Galaxy priors, this translates to the most probable lens masses of ML = 2.65−1.48+5.09 M⊙ and ML = 1.71−1.06+3.78 M⊙, respectively. The limits on the blended light suggest that this event was most likely not caused by a MS star, but rather by a dark remnant of stellar evolution.
Keywords: gravitational lensing: micro, Galaxy: stellar content, stars: black holes, stars: neutron, Astrophysics - Solar and Stellar Astrophysics
Published in RUNG: 13.11.2023; Views: 1831; Downloads: 7
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