Master thesis proposals: Astrophysics and Space Science

Title: Outliers in the black-hole-galaxy scaling relations at lower masses
 
Advisor: Anna Ferre-Mateu
 
Abstract: 
It is now well-stablished that the masses of super massive black holes (SMBHs) are correlated with the properties fo their host galaxy (e.g velocity dispersion, lumionisty), implying that more massive galaxies should contain more massive SMBHs. In addition, this is a strong indication that both the galaxy and the SMBH grow at the same time. However, in the recent years a dozen of extreme outliers have been reported, strongly deviating from the scaling relations and thus challeging the assumed co-evoluiton [1].
 
The aim of this project is to obtain the detailed Star Formation Histories (SFHs) of a sample of outliers at different stellar masses to determine whether there was an event that drastically stopped the formation of new stars and, in this case, when did that happen. We will also derive which were the typical star formation rates before the shut off of the star formation (if any). If the formation of stars was not stopped, were the star formation rates high enough to build a ten times more massive host around these supermassive black holes? Covering a range of stellar masses and galaxy sizes will allow to see if there is any dependence between SMBH and size, a rather unexplored relation. 
 
In this project, the student will use long-slit spectra from the William Herschel Telescope in La Palma and will learn to apply different approaches to derive the stellar populations of integrated spectra (i.e. ages, metallicities, star formation histories).

References:

[1] Ferre-Mateu et al, ApJ, 808, 79 (https://arxiv.org/abs/1506.02663)
 
Contact email: aferremateu@icc.ub.edu
 

Title: Compact massive galaxies in the nearby Universe: clues to galaxy formation scenarios
 
Advisor: Anna Ferre-Mateu
 
Abstract: 
The recent discovery of compact and massive galaxies in the nearby Universe [1] has revolutionized our undestanding of galaxy evolution. Whereas some of such local compact massive galaxies (LCMG) have been revealed as the true relics [2] of the early massive population at z~2 (a.k.a as red-nuggets), a small sample of them have shown to have remarkable amounts of recent star formation activity [3]. It is yet unknown where such star formation activity is coming from and whether it is a global or a local property. If it global, it would favour the assumption that they are massive galaxies in their first phase of formation that simply started forming at later times. If there is a local dependence, it would rather point towards a rejuvenation of the galaxy due to the ingestion of gas. In any case, understanding the role these galaxies play in the galaxy formation paradigm is crucial as they can reveal teh clues for galaxy formation at early epochs.
 
In this project the student will: 
- Create a database with all the measured properties for all the LCMGs known so far (mostly based in [2])
- apply full-spectral-techniques to reveal the star formation histories of the galaxies and derive stellar populations properties: ages, metallicities, abundance patterns.
- Study the scaling relations of LCMGs with these newly derived properties to pose constraints on galaxy formation models. 

References:

[1] Trujillo et al. 2009, 
[2] Ferre-Mateu et al. 2017; MNRAS, 467, 1929 (https://arxiv.org/abs/1701.05197)
[3] Ferre-Mateu et al. 2012; MNRAS, 423, 632 (https://arxiv.org/abs/1203.2623)  
 
Contact email: aferremateu@icc.ub.edu
 

Title: Gamma-ray counterparts of IceCube neutrinos

 
Advisor: Matteo Cerruti
 
Abstract: 
The neutrino window on the Universe is open since 2013 thanks to the IceCube detector [1]. Until recently, no point-like source of astrophysical neutrinos was observed, the flux being consistent with an isotropic component. On September 22, 2017, IceCube observed a high-energy neutrino, whose incoming direction was consistent with the gamma-ray active galactic nucleus (AGN) TXS0506+056, seen with Fermi-LAT and MAGIC in a flaring state [2]. Even though the significance of the association is only at the 3 sigma level, this event has sparkled interest on AGNs as neutrino emitters. Neutrinos and photons from AGNs can be co-produced only if they come from a parent population of relativistic hadrons. A direct association of the two messengers will thus establish AGNs as cosmic-ray accelerators, giving an answer to one of the most fundamental open questions in astrophysics: where do cosmic rays come from? 

The goal of the project is for the candidate to search for gamma-ray AGNs compatible with the arrival directions of the IceCube high-energy neutrino events. Using the lessons learned from TXS 0506+056, he/she will identify potential neutrino emitters on the basis of their spectral and temporal properties. 

References:
[1] ‘’Evidence for High-Energy Extraterrestrial Neutrinos at the IceCube Detector’’,  IceCube Collaboration, Science, Volume 342, Issue 6161, id.1242856 (2013) arXiv 1311.5238

[2] ‘’Multimessenger observations of a flaring blazar coincident with high-energy neutrino IceCube-170922A’’, IceCube, Fermi-LAT, MAGIC, et al., Science, Volume 361, Issue 6398, id. Eaat1378 (2018) arXiv 1807.08816

 
 

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: Finding gamma-ray binary candidates with Gaia DR2

Advisor: Marc Ribó

AbstractGamma-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: Characterizing filaments harboring high-mass star formation

Advisor: Gemma Busquet, Robert Estalella

Abstract:: Filaments are ubiquitous structures in star-forming complexes, which often intersect in high-density regions associated with star formation, known as hub-filament systems. Despite filaments having been recognized more than 30 years ago, the ubiquity of such structures in star-forming regions, which has been recently highlighted by Herschel programs, has brought special attention to their formation mechanism and their role in the star formation process. The aim of this project is to analyze the (J,K)=(1,1) and (J,K)=(2,2) inversion lines of ammonia (NH3) obtained with the 100m Green Bank Telescope to derive the main physical properties of two filamentary Infrared Dark Clouds using the hyperfine structure technique.

References:

[1] Estalella, R. "HfS, Hyperfine Structure Fitting Tool" 2016, PASP in press (arXiv: 1608:04088)

[2] André, P. , Di Francesco, J. ,Ward-Thompson, D. Inutsuka, S.-I., Pudritz, R.E., Pineda, J.E. "From Filamentary Networks to Dense Cores in Molecular Clouds: Toward a New Paradigm for Star Formation" 2014 Protostars and Planets VI, 27-51.

Contact e-mail: busquet@ice.cat , robert.estalella@ub.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.catrobert.estalella@ub.edu


 

Title: Finding an accurate fitting formula for major merger timescales

Adivsor: Josep Maria Solanes

Abstract:: The student will perform binary major merger simulations of galaxies using pre-prepared, cosmologically consistent N-body model and compare the measured timescales with theoretical predictions available from the literature based on the Chandrasekhar formula [e.g. 1,2,3]. The simulations will probe different mass ratios, orbital configurations, halo spins, galaxy morphologies, and orbital energies. Recent calculations [4] have shown that existing analytical predictions, which apply to a wide range of M_sat/M_host ratios, systematically overpredict timescales for major mergers. The main goal of this work is to propose a new, easily implementable fitting formula that accurately predicts the merger timescales in the range M_sat/M_host > 0.25.

Requirements: a minimum level of computer literacy.

References:

[1] Jiang, C.Y. et al. 2008, ApJ, 675, 1095

[2] Boylan-Kolchin, M., Ma C.-P. & Quataert, E. 2008 MNRAS, 383, 93

[3] McCavana, T., et al. 2012, MNRAS, 424, 361

[4] Solanes, J.M., et al, in preparation

 

contact e-mail: jm.solanes@ub.edu


 

Title : Detection of Ultra Faint Dwarf Galaxies in the halo as probes for cosmological models

Advisor: F. Figueras, T. Antoja

Abstract:: Several galaxies with very low luminosity and surface brightness, dominated by dark matter, called "Ultra Faint Dwarf Galaxies" (UFDGs), have been found in the halo of the Milky Way. The detection of more of these systems is extremely relevant for the so-called "missing satellite problem", which is a dramatic discrepancy between the observed number of galaxy satellites and the large number predicted by the state-of-the-art cosmological Lambda-CDM simulations. The Second Data Release of the Gaia catalogue will have full sky coverage and stellar kinematics to review this problem. With the aim to obtain a new and unbiased census of UFDGs in the MW halo with Gaia data we will adapt, improve and test the use of the Wavelet Transform techniques for the UFDG detections [1].

References:

[1] T. Antoja et al. (2016), Detection of satellite remnants in the Galactic Halo with Gaia-III. Detection limits for ultrafaint dwarf galaxies, MNRAS 453, 541. (https://arxiv.org/abs/1507.04353)

contact e-mail: cesca@fqa.ub.edu


Title: Inhomogeneous stellar wind accretion and jet formation in high-energy emitting binaries

Advisor: Valentí Bosch

Abstract:: It is thought that gravitational capture by a compact object of wind from a companion star is not an efficient process to form an accretion disc, as there is not enough angular momentum in the accreted material. The presence of an accretion disc has been considered necessary to form jets, which are emitters of non-thermal emission. On the other hand, as massive star winds are known to be inhomogeneous, the inhomogeneities may have enough angular momentum with respect to the compact object to form small, relatively short lived discs. These discs could be able to launch jets, and fuel the production of high-energy radiation.

 References

 The Effect of Porosity on X-Ray Emission-Line Profiles from Hot-Star Winds Owocki, S. P., Cohen, D. H. 2006, ApJ, 648, 565O

 Direct wind accretion and jet launch in binary systems Barkov, M., Khangulyan, D., 2012, MNRAS, 421, 1351

contact e-mail: vbosch@am.ub.es 


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

http://www.solarorbiter.org/

Contact e-mail: n.agueda@ub.edu


Title: Metal line absorption systems as probes to galaxies in formation

Advisor: Jordi Miralda

Abstract: Numerous absorption systems that are detected in spectra from the Sloan Digital Sky Survey correspond to gas in high-redshift halos in which galaxies are forming, and show absorption lines of many ionized elements that can be used to study the physical state. We would like to measure correlations among these lines and their positions relative to quasars, which can be used to measure the effect of quasar ionizing radiation and establish the physical conditions of the gas.

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: Microlensing events observed by Montsec Observatory in Gaia Science Alerts programme

Tutor: Carme Jordi i Nebot

Advisor: Josep Manel Carrasco Martínez

Abstract:

Some of the Gaia satellite (ESA, 2013) photometric alerts (sources suddenly increasing its flux to be followed up from ground telescopes) are due to gravitational microlensing events. Gravitational microlensing are produced when two stellar type objects are aligned in the line of sight magnifying the light of the background object. This can be used to study in better conditions both the background and the foreground objects using its temporally magnified fluxes. Microlensing is a powerful tool in finding invisible objects, including planets on Earth-like orbits, massive black holes or even Tidal Disruption Events (TDE):

1. Microlensing planets in Gaia

In order to detect a potential planet around the lens an intense follow-up observational campaign is necessary. In this project we propose to observe selected Gaia microlensing events with Observatory Montsec in order to detect a tiny deviation due to planet.

2. Stellar mass black holes from Gaia

In order to recognise if the lens was a black hole it is necessary to obtain good coverage of the light curve to derive the parameters of the lens and to constrain potential black hole mass and distance. The project will require involvement in the observations of microlensing events with Observatory Montsec, data reductions and studies of individual events.

3. Hunt for Tidal Disruption Events

Supermassive black holes in centres of galaxies are often waken up by a star passing a bit too near. The accretion of the star produces a luminous blue flare, called Tidal Disruption Event. Gaia and other transient surveys detect candidates for central transients, however their multi-colour observations from the ground and space (Swift) are required to prove the transient is not just a supernova. In this project selected transients will be observed in detail from Observatory Montsec in order to find new examples of Tidal Disruption Events and measure masses of black holes in nuclei of galaxies.

Contact e-mail: carrasco@fqa.ub.es


Title: Stellar parameter determination using JPLUS photometry

Tutor: Carme Jordi i Nebot

Advisor: Josep Manel Carrasco Martínez

Abstract:

The Javalambre-Photometric Local Universe Survey, J-PLUS (www.j-plus.es), is defined to observe 8500 deg2 of the sky visible from the Javalambre Observatory (Teruel, Spain) with the panoramic camera T80Cam at the JAST/T80 telescope, using a set of 12 broad, intermediate and narrow band optical filters. The Project is particularly designed to carry out the photometric calibration of J-PAS (http://j-pas.org). For this reason, some J-PLUS filters are located at key stellar spectral features that allow to retrieve very accurate spectral energy distributions for more than 5 millions of stars in our Galaxy.

Some of the photometric passbands used in J-PLUS programme were originally proposed by the UB team while designing a photometric system for Gaia Mission in its early instrument design phase, and they were selected due to its ability to disentangle the effect of the astrophysical parameters (effective temperature, surface gravity, metallicity, alpha elements abundances, ...) of the stars in the spectral energy distribution of the stars.

This work aims to define a methodology and code an algorithm able to be used for stellar classification/parameterisation in J-PLUS programme. This methodology can be based on the original studies developed for Gaia passbands using colour-colour diagrams and should be able to do the parameterisation for all stars observed in an automatic and not-supervised way.

Contact e-mail: carrasco@fqa.ub.es


Title: Open clusters as seen by Gaia

Advisor: Carme Jordi /Xavier Luri

Abstract:: Gaia is an space astrometric mission by European Space Agency with launch in November 2013. It is a full sky scanning satellite aiming to measure positions, proper motions and parallaxes for a billion stars in the Milky Way with an unprecedented precision of 15 microarcseconds at magnitude 15. In addition, Gaia will obtain low and high resolution spectra of the observed stars. All this information together will allow to unveil the history of formation and evolution of our Galaxy.

The aim of this master thesis is to analyse the astrometric, photometric and spectroscopic capabilities of Gaia to study open clusters using the simulated Gaia observations produced by the Gaia Object Generator (GOG) simulator developed by the UB team.

Why open clusters? 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. Globular clusters, formed by old and metal poor populations are used to trace the first stages of the Galaxy formation. Open clusters, which cover larger ranges of ages and metallicities, are located in the Galactic disk. Therefore, they are key to investigate its formation and evolution.

The concrete goals are:

  • to simulate Gaia observations of a set of clusters of different richness (i.e. different masses), different ages, different locations in the Milky Way disk in combination with the foreground and background stellar population
  • to analyze the HR diagrams, proper-motion vector point diagrams, etc with their corresponding error bars, that can be used to discuss the capabilities of Gaia for those clusters

References:

About Gaia mission: Perryman et al 2001, A&A 369, 339 http://adsabs.harvard.edu/abs/2001A%26A...369..339P

About Gaia performances: http://www.rssd.esa.int/index.php?project=GAIA&page=Science_Performance

About Gaia Universe Model simulation: Robin et al 2012, A&A 543, A100 http://adsabs.harvard.edu/abs/2012A%26A...543A.100R

Contact e-mail:carme.jordi@ub.edu


Title: Outskirts of open clusters

Advisors: Lola Balaguer, Carme Jordi

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 the their central part, the nucleus. 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.

High quality proper motions of a selection of 40 open clusters have been acquired in a project conducted with the meridian circles of San Fernando at El Leoncito (Argentina) and La Palma. The area covered by the observations is few times larger than the quoted radius of the clusters in the literature, which will let us study their coronas with unprecedented accuracy. For several of those clusters, our team have Stroemgren photometry obtained with the Wide Field Camera at INT.

In this framework, the master thesis projects aims to:

  • select the most promising 2-4 clusters out of the total list of 40 observed, taking into account distance, age, brightness, precision of astrometry and photometry, existing data in the literature, availability of Stroemgren photometry, availability of data from the Gaia-ESO survey, and so on
  • separate stars from the cluster and from the field, using as many information available as possible (proper motions, colour-magnitude diagrams, radial velocities)
  • establish the extension of the selected clusters, their present-day mass function and the degree of mass segregation; and discuss the relationship with age and position in the disk

References:

Balaguer-Núñez, L.; Jordi, C.; Muiños, J. L.; Galadí-Enríquez, D.; Masana, E. Studies on the corona of open clusters. Highlights of Spanish Astrophysics VII, Proceedings of the X Scientific Meeting of the Spanish Astronomical Society (SEA), held in Valencia, July 9 - 13, 2012. Eds.: J.C. Guirado, L.M. Lara, V. Quilis, and J. Gorgas., pp.644-644 (05/2013) ADS link

Balaguer Núñez, L.; Jordi, C.; Muiños, J. L.; Galadí-Enríquez, D.; Masana, E. New Membership Study on the Corona of the Open Cluster M 67. Stellar Clusters & Associations: A RIA Workshop on Gaia. Proceedings. Granada, Spain, May 23 - 27, 2011. Edited by: Alfaro Navarro, E. J.; Gallego Calvente, A. T.; Zapatero Osorio, M. R., pp.375-376 (00/2011). ADS link

Moyano Loyola, Guido R. I.; Hurley, Jarrod R. Stars on the run: escaping from stellar clusters. Monthly Notices of the Royal Astronomical Society, Volume 434, Issue 3, p.2509-2528 (09/2013)

Contact e-mail:lola.balaguer@am.ub.escarme@am.ub.es


Title: Optimization of the Besançon Galaxy model code

Advisors: C. Figueras, X. Luri

Abstract:: The Besançon Galaxy Model (http://model.obs-besancon.fr/) is the best stellar population synthesis model of our galaxy currently available. It has been originally developed by A. Robin and collaborators at the Besançon Observatory, but its latest upgrade and extension has been done in collaboration with our team at the ICCUB.

This model is implemented in Fortran and is the heritage of more than 20 years of development. We plan now to update the code in order to optimize it and prepare its future evolution.

The proposed work is the first step in this process: carry out a full review of the Fortran code in order to

  • Review and update the set of input parameters and ingredients definig the galaxy model, and document them
  • Streamline and simplify the code to prepare it for future applications: IMF and SFH testing
  • Upgrade the code to be able to apply the new philosophy for star generation (Czekaj, 2012 PhD) to the thick disk, the halo and the bulge population

With this work the student will have an opportunity to learn how a galaxy model is built and will obtain first-hand experience on its actual implementation.

References:

A. C. Robin, C. Reylé, S. Derrière and S. Picaud. A synthetic view on structure and evolution of the Milky Way, 2003, Astron. Astrophys., 409:523

Contact e-mail: cesca@am.ub.esxluri@am.ub.es