https://ui.adsabs.harvard.edu/abs/2018A%26A...620A..79M/abstract
https://ui.adsabs.harvard.edu/abs/2019A%26A...624L...1M/abstract
The robotic and wide-field Telescope Fabra ROA at Montsec (TFRM) [1] is surveying since Dec 2011 up to 60 northern fields containing a selection of ~10 cataloged M-dwarfs per field. This survey is called TFRM-PSES (TFRM-Preselected Super-Earths Survey) [2]. Since its launch in Apr 2018, the Transiting Exoplanet Survey Satellite (TESS) [3] is delivering outstanding results in several areas of planetary science. The two largest TESS catalogs of stellar flares have been just released: [4,5] and [6], respectively. These comprise ~25,000 M-dwarfs and ~200,000 FGKM stars, studied with 2 min. cadence, observed during the first two TESS sectors and the first two years of the mission, respectively.
TESS paramount contribution is its combination of all-sky photometry and the ~100-parts-per-million photometric precision that is currently offering. However, TFRM-PSES spans ~7yr more of baseline and, when pointing at a TFRM-PSES field this shows ~4x better cadence than TESS.
The goal of this MSc Thesis is two-fold. In the first part, the student will:
1-select M-dwarfs stars in a single TFRM-PSES field and a short baseline as a working dataset,
2-process the working dataset: use the astrometry and differential photometry routines to get the working light curves from TFRM-PSES images,
3-detect the TFRM-PSES flares by means of the AltaiPony [7] algorithm,
4-compare the flares detection rate of TFRM-PSES flares with respect to the TESS catalogs.
To do so, the student will make sure the baselines and targets overlap.
5-study the flare frequency distribution as a function of spectral type.
6-study possible discrepancies in 4- and 5- with respect to the results published in [4,5,6],
If the first part is completed, the student will undergo the second part. In particular, he/she:
7-one of the main advantages of TFRM-PSES is its longer baseline with respect to TESS. This way, the student will search the literature several M-dwarfs flares outside TESS baseline but inside TFRM-PSES'.
A potentially interesting profile of targets could be M-dwarfs which TESS has detected to have a transiting exoplanet,
8-repeat 1- to 6- for these particular flare events and discuss them,
9-repeat 1- to 6- over a full ten-year baseline TFRM-PSES field.
References:
[2] : Fors, O., Boloix, J., Voss, H., et al. 2012, Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun 17. Poster: https://www.researchgate.net/publication/234016345_First_operational_mo…;
[3] : https://www.nasa.gov/tess-transiting-exoplanet-survey-satellite
[4] : Günther, M.N., Zhan, Z., Seager, S., et al. 2020, AJ, 159, 60. doi:10.3847/1538-3881/ab5d3a. Preprint: https://arxiv.org/pdf/1901.00443.pdf
[5] : Catalog from paper at [4] :https://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/159/60
[6] : Günther, M.N. 2021, Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun, 288. doi:10.5281/zenodo.4569134. Poster: https://zenodo.org/record/4569134#.YUMd830p4uU
[7] : AltaiPony https://github.com/ekaterinailin/AltaiPony
Title: Gamma-ray binaries with the Cherenkov Telescope Array
Advisor: Pol Bordas
Abstract: In the last decade very-high-energy (VHE) astronomy has emerged as a new astronomical window, allowing for the study of the most extreme astrophysical processes in our Universe. The current generation of Cherenkov Telescopes H.E.S.S, MAGIC and VERITAS has revealed the presence of about two-hundred of such VHE sources in the gamma-ray sky [1]. This is however just the tip of the iceberg, and the improved capabilities of the next generation of instruments, the Cherenkov Telescope Array (CTA) [2], is expected to increase this number by about one order of magnitude.
Gamma-ray binaries (GBs) are binary systems where a neutron star or black hole orbits around a “normal” companion star, which display most of their non-thermal radiative output at energies above 100 GeVs [3]. Their emission patterns are thought to trace the (variable or periodic) high-energy processes taking place at different parts of the orbit. Seven systems of this kind have been discovered so far. They are considered unique labs where extremely-efficient particle acceleration and high-energy emission/absorption mechanisms can be studied on “human” time-scales, from minutes to a few months.
In this Project we will study the VHE emission from GBs as observed with CTA. The candidate will make use of dedicated simulation and analysis pipelines (Python-based) in order to retrieve the observation strategy and the array configuration required to constrain the timing and spectral properties of these sources. Mastering these CTA pipelines will also provide the candidate with the needed expertise on the analysis of high-level scientific data on a given galactic/extragalactic VHE gamma-ray source that the observatory will deliver (open-source) in the next years.
References:
[1] TeVCat: http://tevcat.uchicago.edu
[2] CTA: https://www.cta-observatory.org
[3] G. Dubus (2013), A&ARv, 21, 64D (arXiv: 1307.7083)
contact e-mail: pbordas@icc.ub.edu
Title: How many black hole binary mergers came from the globular cluster 47 Tuc?
Advisor: Mark Gieles and Tomas Andrade
Abstract:
The globular cluster 47 Tucanae (47 Tuc) is a massive (10^6 Msun) star cluster in the Milky Way halo. Because of its high mass and relatively close distance (4.5 kpc) there are exquisite observations of this cluster making it an important target for dynamical modelling. By comparing mass models to the latest photometric and kinematic data of 47 Tuc, Hénault-Brunet et al. (2020) found that the cluster has a relatively small black hole (BH) population of ~400 Msun (or ~100 BHs) compared to what is expected from stellar evolution models and the latest prescriptions of BH natal kicks (few 10^4 Msun).
A possible explanation is that 47 Tuc formed with a very high density and lost all its BHs through dynamical slingshots in the dense core. You will run N-body calculations on Graphics Processing Units (GPUs) to simulate the gravitational interactions between stars and BHs, including the effects of stellar evolution and the Milky Way potential, to find the initial mass and density that is required to reduce the BH population to its inferred ~400 Msun. The "best-fit" model provides insight in the demographics of the BH population across cosmic time, which you will use to estimate the contribution to gravitational wave detections of BH binary mergers of 47 Tuc-like clusters.
Requirements: basic programming in python for data analyses and plotting; running fortran N-body code in Linux environment
References:
- Giersz & Heggie 2011, MNRAS, 410, 2698 https://ui.adsabs.harvard.edu/abs/2011MNRAS.410.2698G/abstract
- Hénault-Brunet, Gieles et al. 2020, MNRAS, 491, 113 https://ui.adsabs.harvard.edu/abs/2020MNRAS.491..113H/abstract
- Aarseth 1999, PASP, 111, 1333 https://ui.adsabs.harvard.edu/abs/1999PASP..111.1333A/abstract
contact e-mail: mgieles@icc.ub.edu, tandrade@icc.ub.edu
Title: Properties of eccentric binary black hole mergers from globular clusters
Advisor: Mark Gieles, Tomas Andrade and Ruxandra Bondurescu
Abstract: After the discovery of gravitational waves (GWs, Abbott et al. 2017)The LIGO-Virgo gravitational wave (GW) interferometers have detected several dozens binary black hole binary (BBH) mergers. Various models exist to successfully explain the merger rate and properties of the mergers: they may originate from massive star binaries, or from dynamical interactions in dense stellar systems, such as globular clusters (GCs). Although model predictions differ, the data do not yet allow us to discriminate whether these is a dominant channel, and the relative contribution of each of these channels could be anywhere between 20-90%.
A unique prediction of the dynamical channel is the existence of BBH with measurable eccentricity (i.e. at the LIGO-Virgo frequencies). In this project you will make predictions for the properties of eccentric mergers that occur in GCs as the result of GW capture. You will use the model predictions for the evolution of GCs and their BHs (Antonini & Gieles 2020a,b), and combine these with recipes for mergers following GW capture in single-single and single-binary encounters (Samsing et al. 2020). The goal of this project is to quantify where these eccentric BBH mergers lie in the mass-eccentric diagram.
References:
- Abbott et al. 2016, PhRvL, 116, 061102 https://ui.adsabs.harvard.edu/abs/2016PhRvL.116f1102A/abstract
- Antonini & Gieles 2020a, PhRevD, 102, 123016 https://ui.adsabs.harvard.edu/abs/2020PhRvD.102l3016A/abstract
- Antonini & Gieles 2020b, MNRAS, 492, 2936 https://ui.adsabs.harvard.edu/abs/2020MNRAS.492.2936A/abstractm
- Samsing et al. 2020, PhRevD, 101, 123010 https://ui.adsabs.harvard.edu/abs/2020PhRvD.101l3010S/abstract
Contact e-mail: mgieles@icc.ub.edu, tandrade@icc.ub.edu
Title: Finding gamma-ray binary candidates with Gaia DR2
Advisor: Marc Ribó
Abstract: Gamma-ray binaries are a special class of binary systems that produce Very High Energy (VHE) gamma-ray emission above 100 GeV. Half a dozen of these sources have been discovered up to now thanks to Imaging Atmospheric Cherenkov Telescopes like MAGIC, HESS or VERITAS. They are new laboratories for a variety of physical processes that vary as a function of the orbital phase of the systems. However, not all these processes are fully understood, and the discovery of new systems for further detailed studies is necessary to shed light on gamma-ray binary physics.
In this context, the Gaia DR2 catalog provides a good starting point to find new gamma-ray binary candidates. The goal of this project is to perform a cross-correlation study between Gaia DR2 data, available OB catalogs, and mutli-wavelength data (radio, X-rays, Fermi) to build a catalog of gamma-ray binary candidates to be studied in detail with the future Cherenkov Telescope Array.
Requirements: programming skills in fortran and python
References:
Dubus 2013, A&ARv, 21, 64 (http://adsabs.harvard.edu/abs/2013A%26ARv..21...64D)
Miller-Jones et al. 2018, MNRAS (http://adsabs.harvard.edu/doi/10.1093/mnras/sty1775)
https://gea.esac.esa.int/archive/
contact e-mail: mribo@ub.edu
Title: Study of the cosmological 21 cm line in a biphasic hydrogenic gas medium.
Advisor: Eduard Salvador
Abstract: Much interest is put on the observation of the cosmological 21 cm line as a direct probe for the reionization process in the Universe. The first detection of the 21 cm signal has recently been reported, which appeared to have a very strange unexpected shape. However, all theoretical predictions so far assume that neutral hydrogen causing that signal is in the form of a homogeneous medium at an intermediate temperature between that of ionized hydrogen as found around galaxies and of the neurtral hydrogen found far from them. In this Master thesis we will study the effects in the 21 cm line of actually having a biphasic hidrogen medium, made of ionized bubbles in a neutral background.
contact e-mail: eduard@fqa.ub.edu
Title: The role of the first non-massive stars in the chemical evolution of the early universe.
Advisor: Pilar Gil-Pons
Abstract:: The nature of the first stellar generations and their role in the evolution of the early universe has been a matter of debate during the last decades. Recent 3D hydrodynamical simulations of stellar formation support the occurrence of low- and intermediate-mass primordial (or metal-free) stars. However, the traditional view was that the first stars had to be massive. As a consequence the evolution, the nucleosynthetic yields, and the contribution to the chemical evolution of the universe, of the most metal-poor non-massive stars is not thoroughly understood.
We aim to develop techniques to compare the observed surface abundances of the most metal-poor stars in the Galactic halo to the recently calculated yields of low- and intermediate-mass stars of metallicity Z≲10-5 .Results will be analysed in order to draw conclusions on the role of these stars in the evolution of the early universe.
Contact e-mail: pilar.gil@upc.edu
Title: Unveiling the nature of the HH377 shock throught Herschel-PACS observations
Advisor: Gemma Busquet, Robert Estalella
Abstract:: Molecular outflows are among the most conspicuous manifestations of a nascent star. These outflows are known to result from the entrainment of circumstellar gas, swept up by the primary jet, where a shock front is generated as a consequence of the supersonic impact of the jet with the natal cloud. Shocks heat, accelerate, and compress the ambient gas material switching on a complex chemistry that leads to an enhancement of the abundance of several species. The goal of this project is to investigate the physical conditions of the Herbig-Haro object HH377 of the Cepheus E outflow using spectroscopic data from PACS instruments onboard of Herschel satellite. The observational results will be compared with the shock-model predictions to understand the nature of the HH 377 shock.
References:
[1] Flower, D.R. & Pineau Des Forêts, G. 2010, MNRAS 406, 1745
[2] Hollenbach, D. & McKee C.F. 1989, ApJ 342, 305
[3] Lefloch, B. , Gusdorf, A., Codella, C., Eislöffel, J. , Neri, R. , Gómez-Ruiz, A. I., Güsten, R. , Leurini, S., Risacher, C. & Benedittini, M. 2015, A&A, 581, A4
contact e-mail: busquet@ice.cat, robert.estalella@ub.edu
Title: Proper motions of the L1157-B1 protostellar shock
Advisor: Gemma Busquet, Robert Estalella
Abstract:: Molecular outflows are among the most conspicuous manifestations of a nascent star. These outflows are known to result from the entrainment of circumstellar gas, swept up by the primary jet, where a shock front is generated as a consequence of the supersonic impact of the jet with the natal cloud. Shocks heat, accelerate, and compress the ambient gas material switching on a complex chemistry that leads to an enhancement of the abundance of several species. The goal of this project is to investigate the physical conditions of the HerbieHaro object HH377 of the Cepheus E outflow using spectroscopic data from PACS instrument onboard of Herschel satellite. The observational results will be compared with the shock-model predictions to understand the nature of the HH377 shock.
References:
Flower, D. R. & Pineau Des Forˆets, G. 2010, MNRAS 406, 1745
Hollenbach, D. & McKee, C. F. 1989, ApJ 342, 305
Lefloch, B., Gusdorf, A., Codella, C., Eisl¨offel, J., Neri, R., G´omez-Ruiz, A. I., G¨usten, R., Leurini, S., Risacher, C., & Benedettini, M. 2015, A&A, 581, A4
contact e-mail: busquet@ice.cat, robert.estalella@ub.edu
Title: The Local Universe in the era of Big Data. The global properties of lenticular galaxies with nuclear activity.
Adivsor: Josep Maria Solanes
Abstract::
Lenticular or S0 galaxies were introduced by Hubble as objects that show intermediate morphology between ellipticals and spirals. Today we recognize them as rotating lens-shaped disks of stars which lack spiral arms and host a significant central bulb. By applying machine learning techniques in a sample of many thousands of single-fiber optical spectra of nearby lenticular galaxies, we have recently shown [1] that there are actually two clearly distinct S0 sub-populations: the majority of S0 conform to the classic picture of these objects, in that they exhibit low star formation rates, low extinction and no significant emission lines in their spectra; the other class is made up of bluer galaxies, with significant star formation fed by larger amounts of gas and dust that materialize in an emission-line spectrum. An extra dimension to the two used in the definition of these sub-populations, shows that there is also a subset of S0 galaxies with significant (nuclear) activity.
The goal of this TFM is precisely that the student analyzes the main characteristics of this subset of active lenticulars (with regards to set of control objects) using observations in both X-rays and radio [2,3]. These should allow him/her to determine, together with the optical spectra, whether the electromagnetic radiation of these galaxies is thermal in nature, i.e. produced by massive stars, or the result of the synchrotron emission produced by matter infalling into the central black hole.
The study, which will be co-supervised by researchers from the Instituto de Astrofísica de Andalucía, entails the use of virtual observatory tools, sample characterization, bias identification and analysis, and, finally, running machine learning algorithms. All of this aimed at identifying the most relevant physical parameters of these galaxies and exploring their interrelations and possible dependence on the environment.
Requirements: a reasonable level of computer literacy.
References:
[1] Tous, J.L., Solanes, J.M., and Perea, J.D. 2020, MNRAS, submitted
[2] Jackson, F.E., et al. 2012, MNRAS, 422, pp. 2-13.
contact e-mail: jm.solanes@ub.edu
Title: Milky Way disk dynamics with data analysis
Advisor: Teresa Antoja, Pau Ramos
Abstract: Recently, the European Space Agency’s mission Gaia, with strong participation from the Barcelona team, has measured positions and velocities for an unprecedented number of stars with an unprecedented resolution in our Galaxy, the Milky Way. These measurements show strong disturbances [1,2] possibly due to the effects of the spiral arms and Galactic bar [3] or the perturbations from external galaxies approaching our own [4]. A throughout comparison with models is needed, but so far only a qualitative comparison has been done in part due to the complexity of the features seen in the data.
The student will explore new data analysis tools, never applied to this particular problem, to characterize in a novel and global way the phase space distributions of stars and will apply these methods to both Galaxy simulations and to new Gaia measurements (new data release on 3 rd of December 2020) for a robust comparison. One of the challenges is to analyze all phase space dimensions together and not different 2d projections as done so far. This will be an important step to finally decipher the history of our Galaxy, its interaction with other galaxies, and distinguish between the different (internal/external) perturbations that have affected the Milky Way.
References:
- A dynamically young and perturbed Milky Way disk, Antoja et al. 2018, Nature, 561, 360, https://arxiv.org/abs/1804.10196
- Gaia DR2: Mapping the Milky Way disk kinematics, Gaia Collaboration, Katz, D., Antoja, T., et al. 2018c, A&A, 616, A11, https://arxiv.org/abs/1804.09380
- Transient spiral structure and the disc velocity substructure in Gaia DR2, Hunt, J. A. S., Hong, J., Bovy, J., Kawata, D., & Grand, R. J. J. 2018, MNRAS, 481, 3794, https://arxiv.org/abs/1806.02832
- Footprints of the Sagittarius dwarf galaxy in the Gaia data set, Laporte, C. F. P., Minchev, I., Johnston, K. V., & Gómez, F. A. 2019b, MNRAS, 485, 3134, https://arxiv.org/abs/1808.00451
contact e-mail: tantoja@fqa.ub.edu
Title : Ultrafaint dwarf galaxies and small scale structures in the halo of the Milky Way with Gaia
Advisor: Teresa Antoja, Francesca Figueras, Cecilia Mateu, Pau Ramos, Luis Aguilar
Abstract: Several galaxies with very low luminosity and surface brightness, dominated by dark matter, called Ultrafaint Dwarf Galaxies have been found in the halo of the Milky Way. Among many other aspects [1], these galaxies are important because there may be some tension between the number of observed galaxies and the large number predicted by recent cosmological Lambda-CDM simulations [2].
With this project we aim to find more of these systems and other objects (small cores remaining from stripped galaxies) that may be hidden in the Galactic halo due to their distant location and low number of stars. Since these galaxies are co-moving systems of stars, we will use the advantage of the Gaia mission that measures proper motions (velocities) of a billion stars and look for small over-densities in phase space. The student will use a method already developed by our group [3] and that successfully detected other larger structures in the halo of the Milky Way [4, 5]. These objects are expected to be close to the level of substructure produced by noise, and, as a first step, the student will characterize deeply the noise using simulations without Ultrafaint Galaxies and develop a strategy to find these hidden objects. With this project, we will be able to apply the method to new data from the Gaia mission (made public on the 3 rd of December 2020).
References:
- Galactic Archaeology: The dwarfs that survived and perished, Belokurov, V. 2013, New A Rev., 57, 100, https://arxiv.org/abs/1307.0041
- Where are the missing Galactic satelliters, Klypin A., Kravtsov A. V., Valenzuela O., Prada F., 1999, ApJ, 522, 82, https://arxiv.org/abs/astro-ph/9901240
- Detection of satellite remnants in the Galactic Halo with Gaia-III. Detection limits for ultrafaint dwarf galaxies, Antoja, T., et al 2016, MNRAS 453, 541, https://arxiv.org/abs/1507.04353
- An all-sky proper-motion map of the Sagittarius stream using Gaia DR2, Antoja T., Ramos P., Mateu C., et al. 2020, A&A, 635, L3, https://arxiv.org/abs/2001.10012
- Full 5D characterisation of the Sagittarius stream with Gaia DR2 RR Lyrae, Ramos P., Mateu C., Antoja T., et al. 2020, A&A, 638, 104, https://arxiv.org/abs/2002.11142
contact e-mail: tantoja@fqa.ub.edu
Title : Realistic comparisons between state-of-the-art Milky-Way models and spectroscopic stellar surveys
Advisor: Friedrich Anders, Teresa Antoja
Abstract: In this project, the student will use publicly available high-resolution simulations of Milky-Way-like galaxies (e.g. from the APOSTLE, NIHAO, Auriga projects, [1]) and compare the chemo-kinematic properties to new spectroscopic and astrometric observations of millions of stars in the Milky Way. All simulations were tailored to resemble our Galaxy, but which one comes closest when we look at the details?
The mere existence of large stellar datasets and high-resolution simulations is insufficient to ensure a major knowledge gain about the formation and evolution of our Galaxy. Many datasets are subject to non-trivial selection effects, systematic uncertainties (especially for ages of field stars), and correlated errors that impede straightforward conclusions and affect simplistic model-to-data comparisons [2,3]. There is now an urgent need for more quantitative comparisons of Gaia observations to state-of-the-art Milky Way models and clear indications where such models should be improved.
In this project the student will learn to analyse complex observational and simulation data with python, and how to make physical sense of them. Basic knowledge of Galactic astronomy, statistics, and python programming are necessary.
References:
- https://ui.adsabs.harvard.edu/abs/2018IAUS..334..201S/abstract
- https://ui.adsabs.harvard.edu/abs/2020MNRAS.497.4246B/abstract
- https://ui.adsabs.harvard.edu/abs/2020MNRAS.493.2042E/abstract
contact e-mail:fanders@fqa.ub.edu, tantoja@fqa.ub.edu
Title : Analysing the open-cluster population of the Milky Way with StarHorse
Advisor: Friedrich Anders, Alfred Castro, Tristan Cantat-Gaudin, Carme Jordi
Abstract:
Star clusters are important benchmarks for stellar evolution, the cosmic distance scale, and Galactic structure. Their main physical parameters (age, distance, metallicity) can be determined much more accurately than this is possible for individual stars. Using data from the Gaia mission, the GaiaUB group has recently produced the largest and most complete homogeneous catalogue of Galactic open clusters, including precise ages, distances, and interstellar extinctions [1,2]. This catalogue can now be used to also calibrate physical parameter estimates for individual cluster members, and even field stars.
In [3], stellar parameters for more than 200 million Gaia stars were obtained from fitting astrometric and photometric observations to stellar evolutionary models. Improved estimates will soon be produced by the GaiaUB group using the upcoming Gaia EDR3 data release, scheduled for December 2020. A profound analysis of cluster member stars needs to be undertaken to understand possible systematic effects in the Gaia-derived stellar parameters, and on the other hand these parameters will allow for a better characterisation of the star clusters, and consequently a statistical analysis of the open-cluster population regarding masses, binarity fractions, and differential reddening.
In this project the student will learn to analyse large observational datasets with python, and how to make physical sense of them. Basic knowledge of Galactic astronomy, statistics, and python programming are necessary.
References:
[1] https://ui.adsabs.harvard.edu/abs/2020A%26A...640A...1C/abstract
[2] https://ui.adsabs.harvard.edu/abs/2020A%26A...635A..45C/abstract
[3] https://ui.adsabs.harvard.edu/abs/2019A%26A...628A..94A/abstract
contact e-mail:fanders@fqa.ub.edu, acastro@fqa.ub.edu, tcantat@fqa.ub.edu, carme@fqa.ub.edu
Title: On the detectability of isolated black holes in molecular clouds
Advisor: Valentí Bosch-Ramon
Abstract: It is expected that about 10^8 isolated black holes (IBH) produced by stellar evolution populate the Galaxy. These objects are expected to accrete from the medium, subsequently producing winds, thermal emission, and potentially, jets and non-thermal energetic radiation. The aim of this project is to estimate the number of IBH that could fill the densest regions of the Galaxy, and explore whether relatively
nearby objects could be detectable from the Earth. As dense environments make detection difficult due to absorption, only the most energetic non-thermal emission will be considered.
References:
Campana, S.; Pardi, M. C., Do molecular clouds contain accreting black holes?, 1993, A&A, 277, 477
Barkov, M. V.; Khangulyan, D. V.; Popov, S. B., Jets and gamma-ray emission from isolated accreting black holes, 2012, MNRAS, 427, 589
Bosch-Ramon, V.; Bellomo, N., Mechanical feedback effects on primordial black hole accretion, 2020, A&A, 638, 132
contact e-mail: vbosch@fqa.ub.edu
Title: Reconstruction of directional distributions of solar energetic particles in the inner heliosphere
Advisor: Neus Agueda
Abstract:: Solar eruptions release huge amounts of solar energetic particle (SEP) radiation in the heliosphere that can damage satellites and impair terrestrial aviation. Our understanding of SEP events is mostly based on remote electromagnetic observations of the Sun (in white light, X-rays, and radio) and detailed in-situ observations of their directional distributions, energy spectra, composition and time evolution. The goal of this project will be to assess how well the EPD experiment to fly on board the upcoming Solar Orbiter mission will be able to map particle directional distributions. Solar Orbiter will travel to the innermost regions of our solar system to better understand and predict the Sun. Being closer to the Sun will be a challenge from a technological point of view, and it will modify the properties of the observed SEP distributions. Will four fields of view be enough to resolve the anisotropic particle distributions expected close to the Sun?
Requirements: programming skills in IDL or Fortran
References:
http://adsabs.harvard.edu/abs/2014A%26A...570A...5A
http://adsabs.harvard.edu/abs/2009AdSpR..44..794A
Contact e-mail: n.agueda@ub.edu
Title: Connecting Cosmology and Local Group Dynamics to study the Dark Matter
Advisor: Jordi Miralda
Abstract:
Dark Matter constitutes most of the matter in the Universe, but we do not know what it is. The detailed study of orbital motions of galaxies may lead to the discovery of new clues to the nature of dark matter.
New data from the Gaia mission and other observations of nearby dwarf galaxies opens a new opportunity: we are now measuring not only sky positions and redshifts for many stars and dwarf galaxies in the Local Group, but also proper motions and distances. The project will explore a simple way of computing the orbital evolution of many dwarf galaxies
in our Local Group, from the original Hubble expansion after the Big Bang to the present collapse of the Local Group and tidal disruption of dwarfs generating tidal tails. This will combine simple techniques of cosmological simulations
and Local Group dynamical modeling.
Contact e-mail: miralda@icc.ub.edu
Title: The effect of radio-mode heating on galaxy evolution
Advisor: Alberto Manrique
Abstract::
The most important feedback from AGNs is the mechanical reheating of the gas inside galaxies (Springel 2005). A second AGN feedback is the so-called radio-mode heating of the hot intrahalo gas (Croton et al. 2006) taking place when the MBH lies within a naked spheroid directly fed by cooling flows with small angular momentum. In this case, a small fraction of the bolometric AGN luminosity is transferred mechanically to the hot gas in the halo through relativistic jets (Croton et al. 2006, Allen et al. 2006), which slows down the cooling of the hot gas there, possibly even halting it. Such reheating is completely determined by the amount of cold gas feeding the MBH and the AGN radiation.
The aim of the work is to implement a self-consistent computation of the radio-mode heating in the semianalytic model AMIGA (that follows the formation and coupled evolution of galaxies and the inter-galactic medium) to reliably assess the strength of this AGN feedback on galaxy evolution.
References:
Allen, S. W., Dunn, R. J. H., Fabian, A. C., Taylor, G. B., & Reynolds, C. S. 2006, MNRAS, 372, 21
Croton, D. J., Springel, V., White, S. D. M., et al. 2006, MNRAS, 365, 11
Springel, V. 2005, MNRAS, 364, 1105
Contact e-mail:a.manrique@ub.edu
Title: Find a virialized halo finder
Advisor: Josep Maria Solanes
Abstract:: Galaxies within galaxy groups and clusters nowadays can be routinely identified in numerical simulations using methods based on identifying locally overdensities. Most popular halo finders include a final step in which all substructure candidates are subjected to a gravitational unbinding procedure where only the self-bound part is retained (see, e.g. [1]). However, distinguishing the central truly virialized galactic halo from the extended infall region surrounding it is usually a notoriously difficult task.
One possibility, used e.g. by [2], is to measure the spherical mass density profile of galaxies, and determine the radius at which the profile begins to level off and be dominated by the background density. Among the disadvantages of this procedure are that galaxy halos usually are not intrinsically spherical, and that the mass profiles of neighboring galaxies may overlap one another, complicating the calculations.
Another possibility is to attempt a dynamical distinction to separate the two components in velocity space [3]. This works well for central cDs of massive galaxy clusters, but is less robust when the velocity dispersions of the two components are similar and therefore difficult to discriminate. The source of this unsolved problem can be traced to the arbitrariness that accompanies the calculation of the binding energy of a particle, because the potential energy of particles depends on the total mass and shape of the source region adopted [4]. This means that there is no way to tell a priori which mass contributes to the galaxy's virialized core and which does not.
Without a doubt this Master project is not for the faint hearted. If you consider yourself a person with great brains and you like to solve complex problems this challenge suits you: would you be able to find a technique that unambiguously separates the relaxed cores of galaxies from their secondary infall region?
References:
[1] Maciejewski, et al. 2009, MNRAS, 396, 1329. Link
[2] Rudick, et al. 2011, ApJ, 732, 48
[3] Dolag, K., Murante, G., & Borgani, S. 2010, MNRAS, 405, 1544
[4] Han, et al. 2012, MNRAS, 427, 2437
Contact e-mail:jm.solanes@ub.edu
Title: Outskirts of open clusters with Gaia and WEAVE
Advisors: Carme Jordi, Lola Balaguer
Abstract: Stellar clusters are crucial in the study of a variety of topics including the star formation process, stellar structure and evolution, dynamical interaction among stars, or the assembly and evolution of galaxies. In fact, most stars, including the Sun, are formed in stellar clusters although most of them are dissolved in the first few Myr. Open clusters are usually distinguished by their higher stellar density in contrast with the sourrounding sky. Most often, their study is restricted either to the brightest stars and/or to their central part, the core. Although this may be enough for the determination of distance and age, it does not suffice to derive the present-day mass function, the total mass, the extension or the internal structure and mass segregation. Thanks to Gaia Early Data Release 3 (EDR3) we have astrometry and photometry for 1.5 billion sources, the most precise all-sky catalogue to date. Previous investigations by our group based on Gaia DR1 and DR2 (2016, 2018) have revealed previously unnoticed open clusters, some of them showing extended coronas and tidal tails due to the disc gravitational potential. We plan to run our detection algorithm on EDR3 data and discover new clusters as soon as the data is made public (foreseen 3th Dec 2020).
Gaia is providing radial velocities ‘only’ to about 13 magnitude, while astrometry and photometry go down to about 21 magnitude. The multi-fibre spectrograph WEAVE at the William Herschel Telescope aims to complement Gaia with radial velocities and elementary chemical abundances. In this framework, the master thesis master project aims to:
- select a set of well extended clusters from the current catalogue plus the new additions from EDR3,
- search for bona-fide members at the outskirts where the cluster/field populations contrast is very low by using astrometry, photometry and spectroscopy,
- analyse the radial profile and mass segregation of intermediate and old clusters as a function of age and galactic position,
- based on all above, establish the strategy for assigning priorities for WEAVE observations.
References:
- Castro-Ginart, A., Jordi, C. et al, 2020, “Hunting for open clusters in Gaia DR2: 582 new open clusters in the Galactic disc”, Astronomy & Astrophysics, 635, A45
- Balaguer-Núñez, L., et al, 2020 “Clusterix 2.0: a virtual observatory tool to estimate cluster membership probability”, Monthly Notices of Royal Astronomical Society, 492, 5811
- Gaia web: https://www.cosmos.esa.int/web/gaia
- Gaia EDR3 overview: https://www.cosmos.esa.int/web/gaia/early-data-release-3
Contact e-mail:l.balaguer@fqa.ub.edu, carme@fqa.ub.edu
Title: Multiple stars in open clusters based on Gaia
Advisors: Carme Jordi, Lola Balaguer, Eduard Masana
Abstract: Stellar clusters are crucial in the study of a variety of topics including the star formation process, stellar structure and evolution, dynamical interaction among stars, or the assembly and evolution of galaxies. In fact, most stars, including the Sun, are formed in stellar clusters although most of them are dissolved in the first few Myr. Open clusters are usually distinguished by their higher stellar density in contrast with the surrounding sky. Most often, their study is restricted either to the brightest stars and/or to their central part, the core. Although this may be enough for the determination of distance and age, it does not suffice to derive the present-day mass function, the total mass, the extension or the internal structure and mass segregation.
Thanks to Gaia data releases with its exquisite high quality photometry we have been able to observe clear sequences of equal mass binary pairs 0.75 mag brighter than the cluster sequence. Pairs with less massive secondary are hidden in the sequence, and triples are scarce and difficult to detect.
The Gaia Early Data Release 3 (EDR3) is foreseen to be public in 3th Dec 2020, with astrometry and photometry for 1.5 billion sources with even more precise astrometry
and photometry than previous releases. Our team plans to redetermine membership of the currently known clusters and discover new ones. In this framework, the master thesis master project aims to:
- select a set of nearby clusters (to have extended clusters sequences in the colour-magnitude diagram) with a reasonable spread of ages and well visible sequences of multiple stars,
- simulate the stellar population of those clusters using the Gaia Object Generator and derive the multiplicity fraction that better reproduces the observed colour- magnitude diagrams,
- study the dependence of multiplicity fraction with age and galactic position.
References:
- Gaia Collaboration, Babusiaux et al, 2018, “GaiaData Release 2:Observational Hertzsprung-Russell diagrams”, Astronomy & Astrophysics, 616, A10
- Castro-Ginart, A., Jordi, C. et al, 2020, “Hunting for open clusters in Gaia DR2: 582 new open clusters in the Galactic disc”, Astronomy & Astrophysics, 635, A45
- Liu, L. et al, 2020 “Modelling unresolved binaries of open clusters in color-magnitude diagram. I. method and application of NGC3532”, https://arxiv.org/pdf/2008.04684.pdf
- Gaia web: https://www.cosmos.esa.int/web/gaia
- Gaia EDR3 overview: https://www.cosmos.esa.int/web/gaia/early-data-release-3
Contact e-mail: emasana@fqa.ub.edu, carme@fqa.ub.edu
Title: Using unsupervised machine learning to detect open clusters in phase space
Advisors: Carme Jordi, Alfred Castro-Ginard, Friedrich Anders
Abstract: The application of data mining techniques to the Gaia archive has provided with lots of new insights on the Milky Way galactic structure and evolution. In particular, the Gaia UB group reported the detection of hundreds of new open clusters by clustering stars with similar positions and proper motions together [1]. However, the use of these techniques has been found to be less effective in the Solar neighborhood due to the strong projection effects for these nearby stars [2].
In this project, the student will explore the inclusion of radial velocities (using 6-D information for each star) and alternative approaches to optimise the open cluster search for nearby objects. The student will learn how to analyse large catalogues with the use of novel data mining techniques. Basic knowledge of Galactic astronomy, statistics, and python programming are necessary.
References:
- [1]: https://ui.adsabs.harvard.edu/abs/2020A%26A...635A..45C/abstract
[2]: https://ui.adsabs.harvard.edu/abs/2020A%26A...635A..45C/abstract
Contact e-mail: carme@fqa.ub.edu, acastro@fqa.ub.edu, fanders@fqa.ub.edu
Title: Study of M-dwarfs flares in the TESS era and their implications in exoplanets atmospheres chemistry
Advisors: Octavi Fors and Andrea Butturini
Tutor: Carme Jordi
Abstract: The Transiting Exoplanet Survey Satellite (TESS) [1] is delivering outstanding results in several areas of planetary science.
The two largest TESS catalogs of stellar flares have been just released: [2,3] and [4], respectively. These comprise ~25,000 M-dwarfs and ~200,000 FGKM studied stars, both with 2 min. cadence, observed during the first two TESS sectors and the first two years of the mission, respectively.
Our multidisciplinary team, is involved in the study of M-dwarfs flares and their implications in exoplanets habitability. This way, the ultimate goal of this MSc Thesis is to develop from [5] a flare-exoplanet atmosphere interaction photo-chemistry model.
This model should be able to provide depleted/catalyzed species rates, and finally be validated by the observed TESS flare frequency distributions.
More in detail, the student will:
1-get a working sample of flaring stars from TESS flares catalogs,
2-obtain the stellar parameters for the flaring stars,
3-obtain a sub-sample of flaring stars with known transiting planets,
4-obtain the orbital elements from the previous planets,
5-get another sub-sample with only those planets within the habitable zone,
6-as regard as the adaptation and implementation of the photo-chemistry model in [5],
this project considers two distinct evolutionary scenarios:
6.1-the current Earth atmosphere, where the ozone depletion would be the species to model,
6.2-the putative Archean Earth atmosphere, where prebiotic chemistry processes linked to species,
such as SO^2−_3 and HS^− [6], could be catalyzed by UV radiation from flares.
Requirements: previous programming skills in Python and Linux.
References:
[1] : https://www.nasa.gov/tess-transiting-exoplanet-survey-satellite
[2] : Günther, M.N., Zhan, Z., Seager, S., et al. 2020, AJ, 159, 60. doi:10.3847/1538-3881/ab5d3a . Preprint: https://arxiv.org/pdf/1901.00443.pdf
[3] : Catalog from paper at [2] :https://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/159/60
[4] : Günther, M.N. 2021, Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun, 288. doi:10.5281/zenodo.4569134 . Poster: https://zenodo.org/record/4569134#.YUMd830p4uU
[5] : Tilley, M.A., Segura, A., Meadows, V., et al. 2019, Astrobiology, 19, 64. doi:10.1089/ast.2017.1794 .
Preprint: https://www.liebertpub.com/doi/pdf/10.1089/ast.2017.1794
[6] : Rimmer, P.B., Xu, J., Thompson, S.J., et al. 2018, Science Advances, 4, eaar3302. doi:10.1126/sciadv.aar3302 .
Preprint: https://arxiv.org/pdf/1808.02718.pdf
Contact e-mail: octavifors@icc.ub.edu, abutturini@ub.edu
Title: High-precision crowded-field PSF photometry of optical counterparts of X-ray sources in the Kepler and TESS eras
Advisor: Octavi Fors
Tutor: Marc Ribó
Abstract: The monitoring of light curves of optical counterparts of X-ray sources implies in most cases to pinpoint low Galactic latitudes, where crowded fields are frequent. The missions Kepler and TESS were mainly conceived as exoplanets missions, and since they were focused on pointing stability and flux collection, they did not emphasize imaging. Kepler and TESS pixels were therefore large: 4 arcsec and 21 arcsec, respectively. As a consequence, their aperture photometry of crowded fields becomes very challenging, since multiple varying targets are likely to be convolved. PSFMachine [1] is a Python tool for creating models of instrument effective Point Spread Functions (ePSFs), also known as Pixel Response Functions (PRFs). These models are then used to fit a scene in a stack of astronomical images. PSFMachine is able to quickly derive photometry from stacks of images and to separate crowded sources. PSFMachine was recently implemented for Kepler images [2]. However, PSFMachine is not guaranteed to work for K2 (Kepler extended mission along the Ecliptic) and TESS data.
The ultimate goal of this MSc Thesis is two-fold. In the first part, the student will:
- select some optical counterparts of X-ray sources located in the Kepler Field. Some of these sources should be in crowded fields and the rest should be at sparse fields,
- validate that PSFMachine delivers both better photometric precision and periods search significance with respect to aperture photometry, specially for the crowded-field sources.
If the student meets the first part, in the second part of the Thesis he/she will:
- adapt the PSFMachine implementation for K2 or TESS data (to be decided),
- select some optical counterparts of X-ray sources located either in K2 footprint or all-sky (if TESS).
- validate that PSFMachine delivers both better photometric precision and periods search significance with respect to aperture photometry, specially for the crowded-field sources.
PSFMachine is a novel technique that has a large potential for the scientific exploitation of all-sky TESS data.
Requirements: previous programming skills in Python and Linux.
References:
[1]: PSFMachine: https://github.com/SSDataLab/psfmachine
https://ssdatalab.github.io/psfmachine/
[2]: Hedges, C., Luger, R., Martinez-Palomera, J., et al. 2021, AJ, 162, 107. doi:10.3847/1538-3881/ac0825
Preprint: https://arxiv.org/pdf/2106.08411.pdf
Contact emails: octavifors@icc.ub.edu, mribo@fqa.ub.edu
Title: Constraining the Galactic Potential using outer disc substructures
Supervisors: Chervin Laporte, João Amarante, Sergey Koposov
Abstract
The outer disc of the Milky Way (MW), where orbital timescales are of the order of ~1Gyr holds valuable information about the Galaxy's past and current interactions with satellite galaxies. These interactions cause the formation of tidal arms in the outer disc which remain coherent over several Gyrs and can be witnessed at present as long thin stream-like structures with witdth ~1-10 degrees and spanning lengths of ~180degrees on the sky. The dynamic of these tracer structures is simple, following a single particle orbit which can be exploited to measure the potential and its flattening close to the midplane (Laporte et al. 2019).
In this project, we will use the Anticenter Stream (ACS, Grillmair 2006) to constrain the potential and its flattening in the midplane at ~20kpc (similarly to Koposov 2010). This will also probe the impact of baryons on the sphericalisation of dark matter halos. We will map the ACS in 6-D using the astrometric data from Gaia eDR3 combined with radial velocities from legacy surveys (APOGEE, SEGUE, LAMOST) and fit the orbit of the ACS stream. The results and robustness of the method will also be compared with self-consistent N-body simulations of the interaction of the Milky Way with Sagittarius (Laporte et al. 2018).
Requirements: basic programming in Python, statistics and Galactic Astronomy would be a plus but can be learned throughout the project.
Bibliography
1) Laporte et al. 2018, MNRAS, 481, 286: https://ui.adsabs.harvard.edu/abs/2018MNRAS.481..286L/abstract
2) Laporte et al. 2019, MNRAS, 483, 1427: https://ui.adsabs.harvard.edu/abs/2019MNRAS.483.1427L/abstract
3) Grillmair 2006, ApJ, 651, 29: https://ui.adsabs.harvard.edu/abs/2006ApJ...651L..29G/abstract
4) Koposov, 2010, ApJ, 712, 260: https://ui.adsabs.harvard.edu/abs/2010ApJ...712..260K/abstract
contact email: chervin.laporte@icc.ub.edu
Title: Assembly and fate of the population of ultra-faints in the Milky Way.
Supervisors: Chervin Laporte, João Amarante, Matthew Orkney
The Gaia data release revealed that the stellar halo is dominated by a highly anisotropic and non-Gaussian structure pointing to the remains of a massive merger at high-redshift now better known as the Gaia-Sausage-Enceladus (GSE) merger event (Belokurov et al. 2018, Helmi et al. 2018). While much work has focused on the properties of the Sausage (e.g. Fattahi et al. 2019), little is known about its satellite population (Bose et al. 2020). The aim of this project is to shed some light on the population of galaxies that came with the Sausage galaxy through group infall.
In this project we aim to characterize the accretion history of the Milky Way using a statistical sample of MW-like realisations in order to place the Galaxy in a cosmological context. We will look for systems with accretion histories resembling that of the Galaxy (e.g. those with Gaia-Sausage-Enceladus-like satellites merging at high-z vs those without) and characterise their population of satellite galaxies in particular at the low-mass end (the so-called ultra-faint galaxies, UFDs). We will use the Munich semi-analytic model (Henriques et al. 2020) to track the evolution of ultra-faints and identify systems GSE-host MW-like systems and characterise their luminosity function and chemical properties of their UFDs and compare them to rest of the population of MW-like halos. We will then also look into Auriga (Grand et al. 2017) and TNG50 to find analogues of the Sausage and study their satellite they brought with them as well as their survival and compare them with observations of the stellar halo with Gaia and legacy spectroscopic surveys. Interesting systems will be used to set-up some dynamical numerical experiments to study the fate, distribution and properties of the remains of the galaxies brought with the GSE merger.
Requirements: basic programming in Python or IDL and some knowledge of galaxy formation, but can also be learned during the project.
Bibliography:
1) Belokurov et al., 2018, MNRAS, 478, 611: https://ui.adsabs.harvard.edu/abs/2018MNRAS.478..611B/abstract
2) Helmi et al., 2018, Nature, 563, 85: https://ui.adsabs.harvard.edu/abs/2018Natur.563...85H/abstract
3) Fattahi et al. 2019, MNRAS, 484, 4471: https://ui.adsabs.harvard.edu/abs/2019MNRAS.484.4471F/abstract
4) Bose et al. 2020, MNRAS, 495, 743: https://ui.adsabs.harvard.edu/abs/2020MNRAS.495..743B/abstract
5) Henriques et al. 2020, MNRAS, 491, 5795 : https://ui.adsabs.harvard.edu/abs/2020MNRAS.491.5795H/abstract
6) Grand et al. 2017, MNRAS, 467, 179: https://ui.adsabs.harvard.edu/abs/2017MNRAS.467..179G/abstract
7) Pillepich et al. 2019, MNRAS, 490, 3196: https://ui.adsabs.harvard.edu/abs/2019MNRAS.490.3196P/abstract
Contact email: chervin.laporte@icc.ub.edu
Title: Dissecting the Galactic disc with a flexible substructure detector for Gaia.
Supervisors: Chervin Laporte, João Amarante, Sergey Koposov
Abstract
Determining the structure of the Galactic disc in the optical in the midplane through photometry alone is complicated due to the presence of dust. Recently, using the kinematic information provided by the Gaia eDR3 data, a new map of the Milky Way's outer disc was presented (Laporte et al. 2021) revealing a hierarchy of substructure in the disc using a peak detection algorithm inspired by those used to identify halo centers in cosmological simulations (Power et al. 2003). Nonetheless this is only the tip of the iceberg as close inspection reveals the presence of multiple kinematic peaks coinciding on the sky at a given position on the Celestial sphere. How long and extended are the various coherent disc stream-like structures, what is their overall kinematics, chemistry, age distribution of their stellar populations? Are all these substructures excited as a result of kinematic perturbations from satellite galaxies or do they represent folds in the disc seen in projection?
In this project you will devise an algorithm to refine the current algorithm and identify substructure across the whole disc using data from the Gaia satellite beyond the volume probed by the radial velocity survey (RVS). You will track every peak and connect them as individual coherent structures using Gaussian Mixture models (e.g. Bovy 2011). One obvious application would be to better characterise the outer disc of the Milky Way by dissecting it in a coherent way, but one could equally apply the algorithm to study other parts of the Galaxy (e.g. the bar) if time allows it.
Requirements: basic programming in Python, statistics and Galactic Astronomy would be a plus.
Bibliography
1) Laporte et al. 2021, MNRAS, in press: https://ui.adsabs.harvard.edu/abs/2021arXiv210312737L/abstract
2) Power et al. 2003, MNRAS, 338, 14: https://ui.adsabs.harvard.edu/abs/2003MNRAS.338...14P/abstract
3) Bovy et al. 2011, AnApS, 5, 1657: https://ui.adsabs.harvard.edu/abs/2011AnApS...5.1657B/abstract
Contact email: chervin.laporte@icc.ub.edu
Title: The reaction of a Galactic disc to sloshing dark matter halo
Supervisors: Chervin Laporte, Mike Petersen
Abstract:
When a massive satellite merges within a larger host, it sinks through dynamical friction which not only leaves a wake of particles behind the satellite but also carries out large scale disturbances in the halo which can propagate all the way down to the disc causing warps to form (Weinberg 1998). This sloshing of the dark matter halo acts on larger timescales than direct tidal interactions with the main body of a satellite with the disc and its long-term effects on Galactic discs is not fully understood/known. In this project, you will investigate the effect of the dark matter halo wakes and tides from satellites on discs using a Basis Function Expansion code (EXP, Petersen et al. 2021) to re-simulate to much higher resolution the interaction of a Milky Way-like galaxy in the presence of Sagittarius from a self-consisten N-body run (Laporte et al. 2018) to study the response of the outer disc to a sloshing halo on an extended timescale and the type of fine-grained signatures this leaves imprinted on a disc and compare it with observations in the Milky Way (Laporte et al. 2021).
Requirements: basic programming in Python and C for analysis and running N-body code in Linux (can be learned during project).
Bibliography
1) Weinberg 1998, MNRAS, 299, 499: https://ui.adsabs.harvard.edu/abs/1998MNRAS.299..499W/abstract
2) Laporte et al. 2018, MNRAS, 481, 286: https://ui.adsabs.harvard.edu/abs/2018MNRAS.481..286L/abstract
3) Petersen et al. 2021, submitted to MNRAS :https://ui.adsabs.harvard.edu/abs/2021arXiv210414577P/abstract
4) Laporte et al. 2021, MNRAS, in press: https://ui.adsabs.harvard.edu/abs/2021arXiv210312737L/abstract
Contact email: chervin.laporte@icc.ub.edu
Title: Optical spectroscopy of strong [OIII] emitting star-forming galaxies
Supervisor: Kazushi Iwasawa
Abstract: This project offers an observational study of star-forming galaxies with extreme emission-line properties. The galaxies selected for the project are those emitting strong oxygen emission-lines discovered unexpectedly in the optical spectroscopic identification program for high-redshift quasars. They are reminiscent to the class of compact star-forming galaxies nicknamed as "Green Peas", which some people suspect to be a low-redshift analogue of the re-ionization source in the early universe.
The task is to reduce and analyse optical spectroscopy data already acquired with Gran Telescopio Canarias (GTC), summarise their emission-line properties and compare them with those of Green Peas. You are expected to learn the data reduction and analysis of optical spectroscopy, as well as various properties of star forming galaxies and their importance for understanding the galaxy evolution.
Optionally, the study can be expanded to a multi-wavelength characterisation of those galaxies using publicly available data at radio, IR, and X-ray wavelengths, or a galaxy morphology analysis to examine their sizes using the Subaru HSC survey images.
A computer operating under Linux or macOS is needed. The data reduction/analysis is handled mainly with Python. Some knowledge of the language is beneficial (but you can learn it if not).
Bibliography:
Cardamene et al., 2009, MNRAS, 399, 1191
Matsuoka et al., 2019 ApJ, 883, 183
Amorin et al., 2015 A&A, 578, A105
Wikipedia "Pea galaxies"
Contact email: kazushi.iwasawa@icc.ub.edu
Title: Origin of the very metal poor stars in the disk of the Milky Way
Advisors: Teresa Antoja (UB) & Santi Roca-Fàbrega (Universidad Complutense de Madrid)
Abstract: The most metal poor stars in our Galaxy are the oldest stars and thus prove the early stages of the Galaxy. A large fraction of these stars possibly come from external galaxies that merged with our own in the remote past. Recent observations found a significant number of very metal poor (VMP) stars that are on disk-like orbits, instead of halo-like orbits as expected. These can be the result of galaxy accretion with similar alignment as the Galaxy disk (as opposed to isotropic accretion) or with orbits that tend to align with the disk for other reasons. Some of them could have been born in our Galaxy in an already disk-like shape. In this thesis, the student will analyse the orbits of VMP stars in a simulation in order to disentangle the different origins of this type of stars. Additionally, he/she will be able to analyse data from the WEAVE survey in which our team is participating, for which we will be able start analysing the orbits of VMP stars in the disk of the Galaxy and better quantify the fraction of these types of stars. The combination of observational data analysis and simulations should help us to better understand the origin of these stars and their role in the history of our Galaxy.
In this project the student will learn to analyse zoom-in cosmological simulations and will be among the first ones to analyse WEAVE data.
References:
Tracing the formation of the Milky Way through ultra metal-poor stars, Sestito et al. 2018
https://arxiv.org/abs/1811.03099
Ancient Very Metal-Poor Stars Associated With the Galactic Disk in the H3 Survey, Carter et al. 2021
https://arxiv.org/abs/2012.00036
GARROTXA Cosmological Simulations of Milky Way-sized Galaxies: General Properties, Hot Gas Distribution, and Missing Baryons, Roca-Fàbrega et al 2016
https://arxiv.org/abs/1504.06261
Contact: tantoja@fqa.ub.edu
Title: The impact of satellites on the disk of the Milky Way
Advisors: Teresa Antoja & Pau Ramos (Observatoire Strasbourg)
Abstract: Interactions between galaxies have been studied since long ago. However, the impact of nearby dwarf galaxies on the disk of the Milky Way has been the focus of relatively fewer recent studies. Some of the disturbances seen in the Gaia data (substructures in the R-Vphi plane or the phase spiral) can be due to the past interactions of our Galaxy with the Sagittarius dwarf that approached in several past pericenters. Typically, these interactions leave imprints in the phase space of the perturbed disk that persist but transform with time (phase mixing or self-gravitating). In this project we will study the different imprints that different orbits of the perturber satellite galaxy produce in a disk and how these imprints evolve with time. We will compare these models to a more realistic simulation and evaluate how much the observed imprints can tell us about the conditions of the interactions in the pericenter times.
In this project the student will learn to analyse different simulations (from simple toy models to zoom-in cosmological simulations) and to use Gaia data.
References:
GARROTXA Cosmological Simulations of Milky Way-sized Galaxies: General Properties, Hot Gas Distribution, and Missing Baryons, Roca-Fàbrega et al 2016
https://arxiv.org/abs/1504.06261
A dynamically young and perturbed Milky Way disk, Antoja et al. 2018, Nature, 561, 360
https://arxiv.org/abs/1804.10196
Gaia DR2: Mapping the Milky Way disk kinematics, Gaia Collaboration, Katz, D., Antoja, T., et al. 2018c, A&A, 616, A11
https://arxiv.org/abs/1804.09380
Slowly breaking waves: the longevity of tidally induced spiral structure, Struck et al. 2011
https://arxiv.org/abs/1102.4817
Contact: tantoja@fqa.ub.edu