Around Gaia Alerts in 20 questions

Gaia is a European Space Agency (ESA) astrometry space mission, and a successor to the ESA Hipparcos mission. Gaia's main goal is to collect high-precision astrometric data (i.e. positions, parallaxes, and proper motions) for the brightest 1 billion objects in the sky. These data, complemented with multi-band, multi-epoch photometric and spectroscopic data collected from the same observing platform, will allow astronomers to reconstruct the formation history, structure, and evolution of the Galaxy. Gaia will observe the whole sky for 5 years, providing a unique opportunity for the discovery of large numbers of transient and anomalous events, e.g. supernovae, novae and microlensing events, GRB afterglows, fallback supernovae, and other theoretical or unexpected phenomena. The Photometric Science Alerts team has been tasked with the early detection, classification and prompt release of anomalous sources in the Gaia data stream. In this paper, we discuss the challenges we face in preparing to use Gaia to search for transient phenomena at optical wavelengths.Comment: Text of the poster presented at the IAU Symposium #285 "New Horizons in Time Domain Astronomy", Oxford, UK, 19-23 September 2011, included in the proceedings Eds. R.E.M. Griffin, R.J. Hanisch & R. Seaman. Original poster is available under this link: http://www.ast.cam.ac.uk/ioa/wikis/gsawgwiki/images/3/33/AroundGaiaPoster2011.pd

Constraining the masses of microlensing black holes and the mass gap with Gaia DR2

Context: Gravitational microlensing is sensitive to compact-object lenses in the Milky Way, including white dwarfs, neutron stars or black holes, and could potentially probe a wide range of stellar remnant masses. However, the mass of the lens can be determined only in very limited cases, due to missing information on both source and lens distances and their proper motions. Aims: We aim at improving the mass estimates in the annual parallax microlensing events found in the 8 years of OGLE-III observations towards the Galactic Bulge (Wyrzykowski et al. 2016) with the use of Gaia Data Release 2 (DR2). Methods: We use Gaia DR2 data on distances and proper motions of non-blended sources and recompute the masses of lenses in parallax events. We also identify new events in that sample which are likely to have dark lens; the total number of such events is now 18. Results: The derived distribution of masses of dark lenses is consistent with a continuous distribution of stellar remnant masses. A mass gap between neutron-star and black-hole masses in the range between 2 and 5 solar masses is not favoured by our data, unless black holes receive natal-kicks above 20-80 km/s. We present 8 candidates for objects with masses within the putative mass gap, including a spectacular multi-peak parallax event with mass of $2.4^{+1.9}_{-1.3}\ M_\odot$ located just at 600 pc. The absence of an observational mass gap between neutron stars and black holes, or, conversely, the evidence for black hole natal kicks if a mass gap is assumed, can inform future supernova modelling efforts.Comment: 12 pages, published as Wyrzykowski&Mandel, 2020, A&A, 636, A2

Photometric science alerts from Gaia

Gaia is the cornerstone mission of the European Space Agency. From late 2013 it will start collecting superb astrometric, photometric and spectroscopic data for around a billion of stars of our Galaxy. While surveying the whole sky down to V=20mag Gaia will be detecting transients and anomalous behaviour of objects, providing near-real-time alerts to the entire astronomical community. Gaia should detected about 6000 supernovae, 1000 microlensing events and many other interesting types of transients. Thanks to its on-board low-dispersion spectrograph the classification of transients will be robust, assuring low false-alert rate. We describe the operation of the Photometric Science Alerts system, outline the scientific possibilities and conclude with an invitation to collaborate in the ground-based follow-up Gaia alerts during the early months of the mission when the outcome of the alerting pipeline needs to be verified

Świadomość nadciśnienia tętniczego a palenie papierosów wśród dorosłych Polaków

Background Arterial hypertension (HT) is one the most frequent cardiovascular disease (CVD) risk factor. When the doctor recognizes hypertension he should search for and treat not only HT but also the other risk factors, especially cigarette smoking. Material and methods In 2002 year, we conducted national, cross sectional epidemiological survey NATPOL PLUS aimed to assess prevalence and control of main risk factors in Poland. In the representative sample of 3051 adults (age 18-94, 1664 F, 1387 M) we performed questionnaires, blood pressure and antropometric measurements, as well as laboratory tests. Results Analyses were done in a group of 809 patients with HT. HT diagnosis was based on three separate series of measurements. Correlation between HT awareness and cigarette smoking was found. In smokers (n = 218) only 53.5% of subjects were aware of HT. In nonsmokers (n = 422) this proportion was equal to 65.0%. Among patients aware of HT (n = 495, 61.2% of all subjects with HT) there were 23.6% of smokers, 55.4% of nonsmokers, and 21.0% of ex-smokers. Among patients unaware of HT (n = 314) corresponding figures were: 32.3%, 47.1%, 20.6% (p < 0.05). We also asked all patients with HT the question about their knowledge on methods to prevent CVD. Smoking cessation was mentioned by 45.8% of smokers and 32.2% of ex-smokers (p < 0.001). Only 12.1% of smokers and 18.8% of ex-smokers with HT declared giving up smoking as a method they used to prevent heart disease (p = 0.086). Seventy seven percent of patients (n = 515) with diagnosed HT admitted that they obtained antitobacco counseling from their doctors. Conclusion Prevalence of cigarette smoking in patients with HT that are aware of the disease was only slightly smaller in comparison with subjects unaware of HT. In process of medical treatment of HT the doctors should pay much more attention to diagnose and treat other CVD risk factors, especially cigarette smoking. Arterial Hypertension 2010, vol. 14, no 3, pages 196-200Wstęp Nadciśnienie tętnicze jest jednym z najbardziej rozpowszechnionych czynników ryzyka chorób serca i naczyń. Równolegle z terapią NT powinno się rozpoznawać i leczyć inne czynniki ryzyka, w szczególności palenie papierosów. Materiał i metody W 2002 roku, w ramach programu NATPOL PLUS, reprezentatywna próba 3051 Polaków (zakres wieku 18-94 lata; 1664 K, 1387 M) wypełniła kwestionariusz, a następnie przeprowadzono pomiary ciśnienia i antropometryczne oraz badania laboratoryjne na czczo. Wyniki Wykonane analizy u 809 chorych z NT wykazały związek między świadomością posiadanego nadciśnienia tętniczego a częstością palenia papierosów. Wśród palących (n = 218) jedynie 53,5% było świadomych NT, a wśród niepalących (n = 422) ten odsetek stanowił 65%. Wśród osób świadomych NT (n = 495, 61,2% chorych) palący stanowili 23,6%, niepalący 55,4%, a ci, którzy rzucili 21,0%. Wśród nieświadomych NT (n = 314) odpowiednie odsetki wynosiły: 32,3%, 47,1%, 20,6% (p < 0,05). Na otwarte pytanie o znajomość metod zapobiegania chorobom serca innych niż przyjmowanie leków, wśród osób z NT ograniczenie palenia papierosów wskazywało 45,8% palących oraz 32,2% osób, które rzuciły palenie (p < 0,001). Wśród chorych na NT, których pytano o świadome stosowanie metod zapobiegania chorobom serca na ograniczenie palenia wskazywało 12,1% palących oraz 18,8% osób, które rzuciły palenie (p = 0,086). Wśród osób, u których lekarz zdiagnozował wcześniej NT (n = 515), lekarze zalecali ograniczenie palenia tytoniu u 77,3% palących (p < 0,001). Wnioski Odsetek osób palących papierosy jest wśród chorych świadomych i leczonych z powodu NT tylko w niewielkim stopniu niższy w porównaniu z osobami nieświadomymi NT. W postępowaniu lekarskim u chorych z NT należy intensywniej niż dotąd dążyć do redukcji innych czynników ryzyka, w szczególności palenia tytoniu. Nadciśnienie Tętnicze 2010, tom 14, nr 3, strony 196-20