Ecogia Science Meetings
Past Ecogia Science Meetings (2019-2020)
Presentation Slides
Ecogia Science Meetings 2019-2020
Schedule
Meetings are at 14 in the Castle meeting room at Ecogia
2019-09-02 Marc Audard ** The Promise of the SPICA Infrared Observatory
The SPICA Infrared Observatory has been selected by ESA for further study as part of the M5 competition. It carries 3 instruments, SMI, B-BoP, and SAFARI, covering the 17-230 µm range, with a wavelength resolution R between a few hundred and a thousand, combined with various efficient large area imaging and polarimetry modes. The SPICA telescope will be cooled down to about 8K, effectively suppressing most of the satellite's infrared thermal background, which will allow us to reach down to very low fluxes. SPICA will provide spectroscopic capabilities at a high sensitivity of 2-15 x1e-20 W/m2 (5σ/1hr), much deeper than Herschel. The scientific key objectives of SPICA are i) to reveal the physical processes that govern the formation and evolution of galaxies and black holes, ii) to resolve for the first time the far-infrared polarization, and therefore the magnetic field, of galactic filaments, and iii) to understand the formation and evolution of planetary systems. I will present the SPICA mission, the key scientific objectives, and the foreseen Geneva involvement.
2019-09-09 Dominique Eckert ** X-ray halo scaling relations of supermassive black holes
The evolution of supermassive black holes is known to be tightly connected to the properties of their host galaxy, as evidenced by the famous "Magorrian relation", which shows that the mass of the central black hole is tightly correlated with the luminosity and velocity dispersion of its host galaxy. While the relation has been established for over a decade, the driving mechanism is still debated. One possibility is that the growth of the black hole is mainly governed by the total amount of gas present within the dark matter halo, which fuels the AGN in a self-regulated feedback loop. To test this scenario, we have studied the properties of the hot X-ray halo in a sample of massive galaxies and groups with existing dynamical black hole mass measurements. We find that the gas temperature is tightly correlated with black hole mass and that the scatter of the relation is substantially smaller than for either the bulge luminosity or the velocity dispersion relations. We interpret our results in the framework of the self-regulated feedback scheme and compare them with high-resolution AGN feedback simulations.
2019-09-16 Nami Mowlawi ** Long-period variables in the Gaia era
Long-period variables (LPVs) are red giants that show light variability on time scales of several tens of days to hundreds of days. They comprise semi-regular and Mira variables, that can have variability amplitudes up to several magnitudes in the optical. In Gaia DR2 (April 2018), a catalog of 151'761 LPV candidates with amplitudes larger than 0.2 mag has been published, which doubled the number of known such variables at the time of the release. In this presentation, I will introduce these LPVs and highlight the recent studies performed based on the Gaia DR2 catalog. I will end with some expectations for DR3.
2019-09-23 William Hartley ** Cosmology from combining GW events with optical surveys
The age of gravitational wave astronomy began almost as soon as the advanced-LIGO interferometer was turned on in 2015. Four years later, this new window on the cosmos has already had an impact on a wide range of topics in astronomy, and carries the potential to make a defining contribution to a number of important questions. I will discuss the recent contribution that the combination of optical and GW astronomy has made to the problem of estimating the Hubble parameter - through using GW events as so-called standard sirens. The value of the Hubble parameter is one of the most hotly-debated topics in contemporary cosmology, and the apparent tension between values derived in the local and high-redshift universe offer the tantalising prospect of uncovering the need for new physics in our cosmological model. However, despite the excitement of the spectacular binary neutron star event of 2017, there are ongoing challenges and a great deal of hard work needed to realise the full potential of GW events for this end. I will highlight some of the current H0 results and challenges in pursuit of this goal.
2019-09-30 Maria Sueveges ** Generative Adversarial Networks: first steps for CTA
Generative Adversarial Networks (GANs) are nowadays a hot topic in data science, with amazing performance in some image analysis tasks. In this talk, I will summarise briefly how they are constructed and what they do, and how they could be used for classification tasks in gamma-ray astronomy. I will show the results from a first exploration how they could help bridge the gap between simulated training data and real images, discuss its potential and limitations, and show a couple of more ideas to go further.
2019-10-07 Christos Panagiotou ** NuSTAR view of nearby AGN
In this talk, I will summarize the latest results of my PhD project. I have studied the X-ray spectrum of a sample of nearby Seyfert galaxies observed by NuSTAR, focusing on examining their reflection emission. The applied analysis shows that the reflection behaviour, and probably origin, varies with absorption. The disc is the main reflector in unabsorbed sources and the geometrical or physical relation between disc and corona shapes the reflection strength in these sources. On the other hand, a clumpy obscurer seems to be needed to explain the spectral trends of the heavily absorbed sources. Finally, I will discuss the spectral similarities and differences observed between the various classes of AGN and how these may be explained within the unification model.
2019-10-10 Lucia Pavan ** Technology Transfer at the University of Geneva - an insider view
I will briefly introduce the basics of technology transfer, and show how it is organized specifically at UniGe. A few examples will follow on contributions of astrophysics and/or related fields to the technological and industrial advances in the industry.
2019-10-14 Marco Tucci ** Cosmic Infrared Background (CIB) as a window into primordial non-Gaussianity
In cosmic microwave background (CMB) experiments the cosmic infrared background (CIB) produced by unresolved high redshift galaxies is treated as a nuisance that must be subtracted from the data. In this talk, I will review the basic aspects and issues related to the CIB and I will show that the CIB encodes interesting cosmological information. In particular, the CIB is a sensitive probe of inflationary non Gaussianities. Although Galactic dust dominates over the non_Gaussian CIB signal, I will show that it is possible to mitigate the dust contamination with enough frequency channels especially if high frequencies such as the Planck 857 GHz channel are available. Future space missions should be able to probe the local primordial non-Gaussianity down to an amplitude | f_{NL} | ~< 1.
2019-10-21 Matteo Balbo ** Hide and Seek: ETA Carinae at high energy
Waiting fervently for the next periastron passage of ETA Carinae (February 2020), I will summarise the works done and the discoveries achieved so far, with a special focus at high-energy radiation. This source is indeed the first example of gamma-ray emission from a binary system which does not contain a compact object. Several authors predicted possible gamma-ray emission from colliding wind systems already more than 20 years ago, but this has been discovered (and firmly accepted) only in the recent years, thanks to AGILE, Fermi-LAT and HESS observations. I will comment on the physical processes and discuss the possible high-energy interpretations.
2019-10-28 Lorenzo Rimoldini ** On the classification of variable objects in Gaia
The content of the Gaia DR2 variability tables is richer than it might appear. The DR2 (semi-)supervised classification results include additional variability types and candidates with respect to the ones treated in the type-specific catalogues available in the Gaia archive. The rationale and some features of the variables classified in DR2 are recalled and compared with plans for DR3.
2019-11-04 Andreas Postel ** Episodic accretion in star formation
Episodic accretion plays an important role in the evolution of young stars.Although it has been investigated for a long time, the origin of such episodicaccretion events is not yet understood. I will present our results of Herscheland Spitzer observations and preliminary results from modeling young stellarobjects (YSOs), with a short outlook to our next steps.
2019-11-11 Lingsong Ge ** Hierarchical Bayesian analysis of the AGN X-ray spectra in the XMM-COSMOS field
I will present our recent work of fitting the X-ray spectra of 663 AGN sources in the XMM-COSMOS field, all of which have a spectroscopic redshift. We developed a new approach based on a Bayesian hierarchical model in order to correctly propagate the uncertainties on the components, e.g. reflection and soft-excess, that are present in the X-ray spectra of AGN, but not necessarily detectable in medium-sensitivity surveys. 1000 realistic simulations of AGN spectra have been created and analysed to validate our approach and identify the limitations in the recovery of the main parameters. As preliminary results we reconstruct the Nh distribution of AGN in the COSMOS field using a Bayesian model that takes into account the selection function of the XMM-COSMOS survey. Using the same approach, we explore the relationship between the obscured AGN fraction and luminosity.
2019-11-18 Enrico Bozzo ** A report on a few missions under development/study with UoG participation
I will briefly describe the most interesting aspects of the on-going developments/studies in Switzerland for several space missions in which the University of Geneva (UoG) is involved. These include: Euclid (VIS), Athena, eXTP, THESEUS, K-EUSO.
2019-11-25 Guillaume Desprez ** The Euclid photometric redshift challenge
The Euclid mission is a large photometric survey of the extra galactic sky (~15000 square degrees) that aims to study the dark universe. It expects to observe 10 billion sources, and need an accurate measurement of the redshift for 1 billion galaxies to achieve its goal. Spectroscopic redshifts can be very accurate, but too expensive in terms of telescope time to be used for this 10 years mission, therefore the mission will rely on photometric redshifts (photo-z), less accurate but easier to measure for a large amount of sources.To define the way those redshifts must be produced, the Euclid photo-z team designed a challenge to test the state of the art photo-z codes. Euclid-like photometry have been produced and separated into two catalogs sent to the participant of the challenge, a calibration catalog containing the photometry of the sources and their redshifts and a validation catalog containing only the photometry of the sources for which the participants will have to send their results. The design of the challenge was made to carry out a blind analysis between the different methods.I will present the results of the 13 methods that have been sent back, and their analysis. I will show you the the pros and cons of the different strategies that have been adopted by the participants, taking in account the context of the Euclid mission and its requirements. Finally, I will argue that we can benefit of the difference of strategies of the methods to improve the photo-z prediction for the mission.
2019-12-02 Nicolas Produit ** Latest news about POLAR.
POLAR published the easy things in Nature astronomy. It was polarizationmeasurements of the 5 best GRB we had.The analysis of POLAR now proceeded on several front trying to extractmuch more difficult measurements.- we extracted a pulse resolved spectrum of the Crab (published)- we are working on the polarization of GRB that arrived in POLAR at alarge Zenith angle.- we are working on measuring the polarization of the Crab- we are working on the localization capabilities of POLAR
2019-12-09 Volodymyr Savchenko ** Interoperability and automation in searches for Hard X-ray counterparts of multi-messenger transients with INTEGRAL
The INTEGRAL observatory is equipped with a collection of detectors monitoring the entire hard X-ray sky with over 80% duty cycle, and able to re-point to perform deep and sensitive hard X-ray observations of a large selected sky region.This makes INTEGRAL uniquely valuable in searches for elusive, unpredictable, and short-lived hard X-ray and gamma-ray counterparts of multimessenger transients. I will review the follow-up and dissemination strategy we have developed in these searches, which have in particular allowed to maximize scientific benefit of the first confident detection of the multi-messenger transient. These strategies continue to form the basis of the INTEGRAL follow-up activity of gravitational wave transients in the ongoing LIGO/Virgo O3 run.I will outline how semantically-annotated network of real-time services enables the complete workflow starting from parsing of the emerging scientific information in the machine-formatted alerts as well as human-made publications, then proceeding to the inference of new useful scientific conjectures, and concluding with publishing the provenance-enabled ontology-annotated results in outgoing alerts and linked-data online publications.The core of the platform is built around the mechanisms of workflow introspection and flexible interface-first modular development, allowing the researches to efficiently contribute to the constant improvement and operations ofthe platform by leveraging their core competencies in the collaborative research environment. The synergies and interoperability interfaces developed between different tiers of the platform and external collaborators enable its integration into the larger research and discovery process.
2019-12-16 Skipped
2019-12-23 Holidays
2019-12-30 Holidays
2020-01-06 Holidays
2020-01-13 Andrea Tramacere ** Fitting the spectral energy distribution of blazars with the JetSeT code
JetSeT is an open source Python framework with a C numerical engine, to reproduce radiative and accelerative processes acting in relativistic jets, allowing to fit the numerical models to observed data(git repo: https://jetset.readthedocs.io/en/latest/ doc: https://github.com/andreatramacere/jetset anaconda binaries: https://anaconda.org/andreatramacere/jetset ).I will give a shortened version of the three hours hands-on session that I will teach at the Multi-Messenger Astrophysics School in Asiago next week.
2020-01-20 Carlo Ferrigno ** Looking for signs of clumpy wind accretion in supergiant fast X-ray binaries
I will review the models that are used to interpret the phenomenology of Super Giant Fast X-ray binaries and present preliminary results on the analysis of a set of xmm-newton fill - in program observations ( pi Bozzo).
2020-01-27 Berry Holl ** Exoplanet & brown dwarf detection in Gaia data
The vast majority of the currently known exoplanets and brown dwarfs have been detected by radial velocity and transit surveys,but this might soon change. With the ongoing collection of data by the Gaia ESA spacecraft there will be sufficiently precise epochastrometric information to reliably detect low-mass unseen companions like brown dwarfs and high-mass planets.We will discuss the astrometric detection method, its Gaia sensitivity, and an estimate of the number of detectable systems,which likely will be (much) higher than the number of systems known today! Additionally we will shortly discuss the potentialof detecting transits in Gaia photometry, and the use of Gaia epoch radial velocities.
2020-02-03 Isabelle Santos ** Combining template fitting and machine learning
To perform weak lensing -- one of the science goals of the Euclid mission -- high accuracy redshifts for a large number of galaxies are needed. Two broad families of methods exist to estimate photometric redshift (photo-z), each with their pros and cons: machine learning (ML) methods which rely on training with available spectroscopic data, and template fitting (TF) which rely on models, or templates, provided by the user. Machine learning methods perform well in the part of the parameter space where many training samples are available. However, they lack the ability to extrapolate to new data. Template fitting performs better on high redshift samples for which little training data is available. Yet they are dependent of the galactic models provided by the user, which may fail to contain all the information that can be extracted by training an ML model on representative data. I present avenues of research to combine template fitting and machine learning techniques, to yield better photometric redshift estimates.
2020-02-10 Oluwashina ‘shina’ Adegoke ** RefleX: modeling the radiation field in the accretion flow around agns
Proper modeling of the radiation field around active galactic nuclei (AGNs) is key to our understanding of the physical processes occurring within the different components that make up the regions surrounding these systems. Several of the available models are optimised for a few physical processes at the expense of others and so only approximately mimic the physics in these systems.I will, in this presentation, talk about the ray-tracing code RefleX (Paltani & Ricci, 2017). The code has been developed with the capability to simulate realistically, the physical processes of the propagation of electromagnetic radiation through matter around the central engines of AGNs. I will compare results from RefleX and RXTorus - a RefleX-based torus model - with other standard models in use. I will then focus on the many physical processes (and geometries) that are being simulated and tested with the simulation platform.
2020-02-17 Vitalii Sliusar ** Probing multi-wavelength properties of blazars jets using long-term variability data: from radio to gamma-rays
Relativistic particles in the blazars jets emit radiation at all wavelengths, from radio to TeV gamma-rays. Rotation of the super massive black hole in the center of the accretion disk is the likely source of the power. Particles of the ionised gas via Blandford-Znajek mechanism and magneto-hydrodynamical processes in the black hole vicinity are initially accelerated and are feeded into the jet. Further acceleration takes place due to the propagation of relativistic shocks through the jet, while exact radiation mechanisms are still elusive. Using long-term data for the brightest and closest blazars: Mrk 421 (HBL, z=0.031), Mrk 501 (HBL, z=0.034), I will compare evidences for different radiation scenarios (synchrotron self-Compton, external Compton, hadronic etc.) and temporal properties of these sources based on inter-band cross-correlations, fractional variability and gamma-rays to radio response analysis. Both blazars yield complex, unpredictable timing/spectral variability, strong and fast X-ray flares, broad non-thermal spectral energy distribution (SED) with a two-"hump" structure.
2020-02-24 PhD day
2020-03-02 William Hartley ** The Impact of Spectroscopic Incompleteness for Weak Lensing Surveys
There are two main ingredients required to extract cosmological model parameter from the weak lensing shear signal: the shear correlation function, and the redshift distribution of the source galaxies. One method to estimate the redshift distribution is to use a sample of galaxies with confident spectroscopic redshifts that have been observed with the same filters as the target lensing same. We construct a weighted histogram in redshift, where the weights compensate for any mismatch in sampling between the spectroscopic and target samples. I will discuss the limitations of this approach and estimate the possible biases it can introduce in the context of the Dark Energy Survey.
2020-03-09 Dominique Eckert ** Measuring gas motions in nearby galaxy clusters with XMM/EPIC-pn
Galaxy clusters form through a gradual process of merging of smaller entities under the action of gravity. This hierarchical formation process is still taking place at the current epoch, leading the formation of ever larger structures with total masses in excess of 1e15 solar masses. During merging events, the hot intracluster medium of the merging entities collides, leading to hydrodynamical phenomena (shock fronts, turbulence, adiabatic compression) which heat the gas until it relaxes within the potential well of the newly formed structure. A key quantity for understanding the impact of merging processes and the thermalization of the energy is the velocity field of the gas. While measurements of gas velocities will be achievable with upcoming high-resolution X-ray calorimeters like XRISM and Athena/X-IFU, I will show how in spite of its moderate spectral resolution the EPIC-pn detector on XMM can already be used to measure bulk gas motions in the brightest nearby clusters. This can be achieved by calibrating on-the-fly the energy scale of the pn camera using the bright Cu K-alpha fluorescence line. I will present velocity maps of the Perseus and Coma clusters and describe the implications of these measurements for understanding the merging history of these systems and the thermalization of the kinetic energy.
2020-03-16 Nicolas Produit ** Quantum mechanics and astronomy.
I will try to show that astronomy is not just counting number ofphotons. There is much more we can do with all the signals that comefrom the objects in the sky. I will discuss some quantum phenomena andthe perspective they open for astronomy.
2020-03-23 Volodymyr Savchenko ** Status and prospects of hard X-ray follow-up of GW events
As the third run of the GW networks nearing its end in one month,and the next run expected after a long shutdown (according to amonth-old plans), I will summarize the conclusions of our gamma-ray andhard X-ray follow-ups so far, touching some theoretical work, focusingon what exactly did we learn in this activity, and what can we plan andexpect to learn in the near future.
2020-03-30 Isabelle Santos ** The mystery of the filamentary structures in theLOFAR data
With the advent of low-frequency observatories such as LOFAR, Faraday tomography can be used to observe the interstellar medium (ISM). This method reveals thin straight lines with no polarized emission. These depolarization canals have been shown to be aligned with other tracers of the ISM in certain areas of the sky, but their nature has not yet been determined. This works is one step towards the characterization of these depolarization canals by investigating the alignment between them and other tracers in an area around the Draco Nebula.
2020-04-06 Christos Panagiotou ** The Fourier Resolved Spectrum of NGC 5548
NGC 5548, an archetypical AGN, was the subject of a large monitoring campaign in 2014. The source was observed simultaneously from optical to X-rays for a period of more than 4 months, with a high cadence of almost 2 observations per day in some bands. The X-ray variability was found to lead the UV/optical one, while the wavelength dependence of the estimated time lags seemed to follow the relation expected for a simple accretion disc. In this talk, I will present the results of studying the multiwavelength variability of the source in the Fourier space and of reproducing the observed variability amplitudes as the outcome of X-ray reprocessing by the disc using state-of-the-art response functions. The modelling of the variability amplitudes offers a new way to study the inner geometry of AGN.The observed variability can be well reproduced for typical values of the accretion rate and the position of the X-ray source. While these results are not consistent with the values obtained from the observed time lags, this discrepancy can be resolved if a truncated accretion disc or intrinsic absorption is assumed.
2020-04-13 Holidays
2020-04-20 Skipped
2020-04-27 Skipped
2020-05-04 Guillaume Desprez ** How to detect galaxy clusters ?
With the forthcoming large extragalactic photometric surveys (e.g. Euclid, LSST) billions of galaxies will be observed. Some of these galaxies are gathered in massive structures called galaxy clusters. These clusters are interesting from an astrophysical and cosmological point of views. The distribution in mass and redshift of the galaxy clusters is a probe to test cosmological models, and ,due to the dense environment the galaxies in clusters undergo a different evolution from the fields galaxies.It exists several methods that are used to detect galaxy clusters from X-rays to radio wavelength. I will present a review of different ways of detection that are considered in the context of optical and near-infrared photometric surveys.
2020-05-11 Marc Audard ** Gaia: Toward DR3
A review of steps toward the third data release of Gaia.
2020-05-18 Oluwashina ‘shina’ Adegoke ** Ultraviolet to X-ray Comptonisation Delay in Mrk 493
The broadband X-ray emission from type 1 active galactic nuclei, dominated by a power-law continuum, is thoughtto arise from repeated inverse Compton scattering of seed optical/UV photons by energetic electrons in a hotcorona. The seed optical/UV photons are assumed to arise from an accretion disc, but direct observationalevidence has remained elusive. Here we report the discovery of variations in the UV emission preceding thevariations in the X-ray emission based on ∼100 ks XMM-Newton observations of the narrow-line Seyfert 1 galaxyMrk 493. We find that the UV emission leads by ∼5 ks relative to the X-ray emission. The UV lead is consistentwith the time taken by the UV photons to travel from the location of their origin in the accretion disc to the hotcorona, and the time required for repeated inverse Compton scattering converting the UV photons into X-rayphotons. Our findings provide the first direct observational evidence for the accretion disc being responsible for theseed photons for thermal Comptonisation in the hot corona, and for constraining the size of the corona to ∼20rg .
2020-05-25 Lingsong Ge ** AGN X-ray spectral analysis and population inference
Study of AGN population is essential in understanding the evolution of supermassive black holes (SMBHs) and their relation with host galaxies. With larger and larger sample of AGN X-ray spectra, we need methods that automatically fit the spectra and reconstruct their parent population without much bias. Last time I presented our spectral fitting method based on a Bayesian model that correctly propagates on the main spectral parameters like photon index (\Gamma) and hydrogen column density (N_H) the uncertainties due to the presence of secondary, ill-constrained components like reflection and soft-excess, that are present in the X-ray spectra of AGN but not necessarily detectable. In this talk I will briefly recap it and focus on our newly developed Bayesian population inference approaches, which forward-fit the posteriors obtained from spectral analysis. 3000 realistic AGN spectra are simulated and analysed to validate the approaches, and I will show the results of our application to 663 XMM-COSMOS AGN spectra, including the N_H and \Gamma distribution, obscured fraction against X-ray luminosity and its evolution with redshift.
2020-06-01 Holidays
2020-06-08 Carlo Ferrigno ** Discovery of a magnetar X-ray burst with associated fast radio burst.
The INTEGRAL satellite observed serendipitously the Soft Gamma RepeaterSGR~1935+2154 between 2020 April 28 and May 3, during a period ofbursting activity. Several short bursts with fluence in the range10^{-7}-10^{-6} erg cm^{-2} were detected by the IBIS instrument in the20-200 keV range. The burst with the hardest spectrum, discovered andlocalized in real time by the INTEGRAL Burst Alert System, was spatiallyand temporally coincident with a fast radio burst detected by the CHIMEand STARE2 radio telescopes at 400-800 MHz and 1.5 GHz, respectively.The burst light curve in the 20-200 keV range shows three narrow peakssuperimposed on a broad pulse lasting ~0.6 s.The burst spectrum is harder than those of the bursts usually observedfrom this and other magnetars.By the analysis of an expanding dust scattering ring seen in X-rays withthe Neil Gehrels Swift Observatory XRT instrument, we derived a distanceof 4.4_{-1.3}^{+2.8} kpc independent on its possible association withthe supernova remnant G57.2+0.8. At this distance, the burst 20-200 keVfluence corresponds to an isotropic emitted energy of ~10^{39} erg.This is the first burst with a radio counterpart observed from a softgamma-ray repeater and strongly supports the models based on magnetarsthat have been proposed for extragalactic fast radio bursts, despite theenergy budget involved is smaller that that of sourcesat distances of hundreds of Mpc.
2020-06-15 Berry Holl ** Time identification of Gaia DR2 sky maps features and how it can clean your data
Gaia DR2 sky maps can show distinct arc-features, often related to mis-identification due to outliers in the underlying time-series data used to derive the results.Only a small amount of time-series has been published and hence it is usually not possible to re-examine the time-series data.We developed a Java tool that, using the known published scanning law, can identify which time stretches correspond to specific sky coverage regions.This can be used to accurately mask regions and sources on the sky. We will give a small demonstration based on a recently published QSO map (Bailer-Jones et al. 2019).This work is planned to be submitted sometimes this summer so any feedback on this work-in-progress is welcome!
2020-06-22 Andrea Tramacere ** Multiwavelength modeling of the microquasar MAXI J1820+070 during the 2018 outburst, with the JeSeT framework
I will present a self-consistent leptonic model of the multiwavelength SED of MAXI J1820+070from radio to hard-X-ray frequencies, during the 2018 outburst, based on the JetSeT framework.I will discuss the jet magnetic field topology and how it possible to constrain the positionof the acceleration region basing on the spectral properties of the flat-radio spectrum observed in the data.I will show that a compact acceleration region the feed an extended radio jet, with theinclusion of the radiative cooling, can explain the optical to radio data, and can reproducenaturally the flat radio spectrum. I will show also that an irradiated disk plus Comptonizingcorona can explain the UV up to hard-X-ray data.
2020-06-29 Marco Tucci ** Object classification in the Euclid survey
Classification will be an important task for upcoming surveys such as Euclid that will detect billions of new sources. Conventional techniques for star/galaxy classification based on selections in magnitude and morphology are not accurate enough for deep surveys. Machine learning (ML) algorithmsappear instead to be very well suited to classification tasks using morphological and photometric information.We applied different ML approaches to classify objects from simulated and observational datasets, using only photometric information in a configuration similar to the future Euclid survey. The analysis aims to identify the best methods and their performance, considering also Euclid requirements. In the presentation I will show the first results from the analysis and I will discuss future developments.