Theses & Internships at ICE

Do you have a research project in mind?

We offer several opportunities in our institute for students interested in pursuing a research career, such as doing a thesis with us.

The list of available topics to complete Master (TFM) and Bachelor (TFG) thesis is below. If interested, please send your Bachelor/Master academic transcripts and a brief CV to the researcher in charge of the project (CC Esta dirección de correo electrónico está siendo protegida contra los robots de spam. Necesita tener JavaScript habilitado para poder verlo.), indicating the approximate date of your availability.

We also accept official curricular internships, valid for universities. Most of the topics for Bachelor or Master thesis can be possibly downscaled for an internship project. Please bear in mind that we cannot host informal or summer internships.

List of available TFM / TFG projects


TopicICE researchers involvedDescriptionLink
Analysis of the LISA precision for Extreme-Mass-Ratio Inspirals
Carlos Sopuerta

The Laser Interferometer Space Antenna (LISA) is a future Large-class mission of the European Space Agency (ESA) to observe gravitational waves from space, covering the low-frequency band of the gravitational-wave spectrum, a band not accessible for the current ground-based observatories like LIGO and Virgo. One of the main sources of gravitational waves that LISA will observe is the capture and subsequent slow inspiral of a stellar-mass compact object (SCO; typically a stellar-mass black hole or a neutron star) into a supermassive black hole (SMBH) sitting at the center of a quiescent galaxy. Due to the large difference in mass between the SCO and the SMBH, these systems are usually called Extreme-Mass-Ratio Inspirals (EMRIs). The gravitational wave emission of EMRIs is long lasting. It has been estimated that during the last year before the SCO plunges into the SMBH, the system can emit of the order of 100000 gravitational wave cycles. During this emission, the trajectory of the SCO is very close to the SMBH horizon location, which means that the motion is highly relativistic, with strong precession of the periastron as well as of the orbital plane. In this way, during this long emission of gravitational waves, the SCO traces all the near-horizon geometry of the SMBH. This means that the gravitational waves emitted encode a map of the geometry of the SMBH that will allow us to understand the structure of Black Holes with LISA.  To that end, we need first to study the structure of the gravitational waveforms emitted, and from there to estimate the precision with which we will obtain the physical parameters of the EMRIs from the LISA data. The goal of this project is to use simplified models of the gravitational wave emission of EMRIs to estimate the precision in the measurement of the main EMRI parameters: Masses, spin, distance, etc.

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Revealing hidden AGN in dwarf galaxies with radio observations
Mar Mezcua

The supermassive black holes of 109 solar masses found at the center of most massive galaxies are thought to grow from seed black holes of smaller mass formed in the early Universe. Detecting such seeds when the Universe was very young is extremely challenging; however, those seed black holes that did not become supermassive could be observed as active black holes (active galactic nuclei — AGN) in local dwarf galaxies.

We have recently identified a sample of dwarf galaxies possibly hosting AGN. However, the AGN emission at optical wavelengths seems to be outshined by emission from star formation. This TFM aims at analyzing radio observations performed with the Very Large Array of a sample of four AGN candidates in dwarf galaxies. The results can confirm the presence of hidden AGN in these sources, which will have important implications for population studies of AGN in dwarf galaxies as well as for seed black hole formation models. A basic knowledge of python is advisable.

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The Black Hole Universe
Enrique Gaztañaga
The standard model of cosmology assumes that  our Universe began 14 Gyrs (billion years) ago from a singular Big Bang creation. This can explain a vast range of different astrophysical data from a handful of free cosmological parameters. However, we have no direct evidence or fundamental understanding of some key assumptions: Inflation, Dark Matter (DM) and Dark Energy (DE).  Here we propose instead that cosmic expansion originates  from gravitational collapse and bounce of a large scale but low density cloud inside its gravitational radius. This can remove the need to DE, DM and Inflation. The focus of this thesis is to develop theoretical or numerical predictions for the collapse and bounce.
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The Response of the LISA Gravitational Wave Observatory
Carlos Sopuerta

LISA (the Laser Interferometer Space Antenna) is the future third L-class mission of the European Space Agency (ESA) to detect gravitational waves from space in the low-frequency band (between 10 micro-Hertz and 1 Hertz). LISA will detect gravitational waves generated by the coalescence of supermassive black hole binaries; by the capture and subsequent inspiral of stellar-mass black holes into supermassive black holes; by ultracompact binaries in our own galaxy; stellar-mass black hole binaries in the milli-Hertz regime; stochastic backgrounds; etc. In General Relativity, gravitational waves appear two have two independent polarizations, so that a general gravitational-wave emission can be written as a linear combination of these two polarizations, and similarly the response of LISA to it. However, in metric theories of gravity, gravitational waves may have up to six independent polarizations. The goal of this master thesis project is to study the response of LISA to the most general gravitational wave, or in other words, to gravitational waves that contain all possible six polarizations.

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Improving the standardisation of SNe II as cosmological probes
Tomás Müller Bravo

Type II supernovae (SNe II) are the end-point of massive stars and have been used as cosmological distance indicators even before type Ia supernovae (SNe Ia; [1]). Although we do not observe them at large distances as SNe Ia, they offer an independent method to measure the local expansion rate of the Universe, known as the Hubble-Lemaître constant (H0; e.g. [2]). Moreover, their progenitors, environment and explosion mechanism are better understood than those of SNe Ia, making them less prone to biases. This TFM aims to improve the standardisation of SNe II as cosmological probes and use them to better understand systematics in SNe Ia cosmology. The student will gather a sample of SNe II from the literature, use the PISCOLA SN light-curve fitter [3] and analyse the light-curves fits with machine learning techniques in search of alternative parameterisations. The student will also construct a Hubble diagram with SNe II, fit cosmological parameters, and compare and analyse the results against those from SNe Ia.

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Understanding the effect of environment on SNe Ia cosmology
Tomás Müller Bravo

Type Ia supernovae (SNe Ia) are excellent distance indicators. Their standardisation, coming from correlations between their optical peak magnitude, stretch and colour, provides precise measurements of cosmological distances in the Universe (e.g. [1]). Host galaxy information is also used to further improve this standardisation (e.g. [2]). However, the link between SNe Ia and their host galaxies, and their underlying correlation, is still not well understood. This TFM aims to better understand how the environment affects SNe Ia light curves and the possible biases affecting the measurements of host-galaxy properties at high and low redshift. The student will fit SNe Ia with the PISCOLA light-curve fitter [3], measure host-galaxy photometry using HostPhot [4] and estimate galaxy properties via template fitting. In addition, the student will compare galaxy parameters against SNe Ia properties, analyse the physical implications of these and quantify possible biases in the photometry of high- and low-redshift galaxies.

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Exploring the early spectra of SNe II and SNe IIb
Lluís Galbany, Claudia Gutiérrez

Core collapse supernovae are produced by the final explosion of massive stars (>8 Msun). Observationally, they are a heterogeneous class in both spectra and photometry. Because of this, they are broadly separated into objects with hydrogen in the spectra (SNe II) and objects without evidence of hydrogen lines (SNe I; Minkowski 1941). In the hydrogen-poor group, we find objects with (SNe Ib) and without helium (SNe Ic). There are also transitional objects which undergo from being H-dominated (SNe II) in early phases to He-dominated (SNe Ib) at later times. These are named SNe IIb. Given that SNe II and IIb share similar spectroscopic properties at early times, the statistics of the transitional (SN IIb) population are biased to lower numbers because they are initially classified as SNe II in many cases. This project aims to explore in detail the lines observed in SN II and IIb to determine a possible distinction between these two classes. The student will derive these measurements using astronomical tools and programming in python. The sample used for this project comes from the literature.

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Supernova-Remnant properties as function of the metallicity gradient in a galaxy
Maria Kopsacheili

Supernova Remnants (SNRs) play a critical role in the Interstellar Medium (ISM) and consequently in the entire galaxy. They provide it with large amounts of energy, they enrich it with heavy elements, and under appropriate conditions they can trigger new star formation. In addition, the shock wave created after the supernova explosion expands super-sonically into the ISM heating it up to temperatures of ∼ 107K. Therefore, SNRs (along with stellar winds from massive stars) are responsible for the hot component of the ISM [1]. The study of SNR populations gives us the opportunity to explore diverse samples of SNRs that can be correlated to different ISM and galaxy properties. This is very important in order to understand their feedback to the ISM and their role to the entire galaxy. Integral Field Units data, provide an excellent opportunity to this direction, since they allow the multi-wavelength (in the optical regime) study of the SNRs [2] and of their surrounding medium. This TFM aims to explore the SNR-spectral properties as a function of the metallicity in different regions of a galaxy. The student is going to use archival IFU data of nearby galaxies, to calculate the metallicity of different regions of the galaxy, and to explore correlations between metallicities and spectral properties of newly identified SNRs [3].

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Testing spectral models to constrain the metallicity of SN II progenitors
Lluís Galbany, Claudia Gutiérrez

Hydrogen-rich supernovae (SNe II) are produced by the final explosion of massive stars (>8 Msun). They retain a significant fraction of hydrogen at the moment of the explosion, and hence their spectra show prominent Balmer lines. Recently, SNe II have been proposed as metallicity indicators, making them relevant in the cosmic context. More precisely, theoretical models predict that the strength of metal lines around 50 days post-explosion is related to the metallicity of the SN progenitor [1]. Thus, SN II metal-line pseudo-equivalent-widths (pEWs) generally become stronger when metallicity increases. This project aims to explore this correlation and test the parameter space obtained from the models. The student will work with observations and models, astronomical tools and python codes. The sample used for the project comprises spectra from the literature and new observations, plus theoretical models developed by Dr Luc Dessart.

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Measuring the Hubble constant with Type Ia supernovae in the near-infrared while studying its diversity
Lluís Galbany

Type Ia supernovae (SNe Ia) are one of the most precise extragalactic distance indicators. Their peak brightness at optical wavelengths can be standardized based on two empirical relations using their color at maximum and their brightness decline (e.g. [1]). However, there is recent evidence that at near-infrared (NIR) wavelengths, type Ia supernovae are natural standard candles, and they would not need such corrections [2]. The main goal of this project is to provide an updated measurement of the Hubble constant (H0) using SNe Ia observations in the NIR J and H bands, while studying different parametrizations of their light-curves, and testing up to which extent SNe Ia are more homogeneous in the NIR compared to the optical. All these by using a sample of objects with observations in both wavelength regimes that cover epochs before maximum and up to a few weeks past-maximum light. The student will extract the main photometric properties by both performing gaussian process interpolation and template-fitting to SN Ia light-curves with the versatile SNooPy [3] code. Interesting light-curve parameters to extract include the time and peak magnitude of the primary and secondary maxima, and at the bottom of the valley between maxima in the NIR bands. Hubble diagrams will be constructed for every single band, and H0 will be determined from the best fit cosmology. The scatter between SN distances and the best cosmology will be compared among bands, and dependencies between the scatter and any of the extracted parameters will be studied.

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Characterization of subluminous 1991bg-like Type Ia supernovae
Lluís Galbany

Type Ia supernovae (SNIa) are one of the most precise distance indicators to distant galaxies, once their peak brightness is standardized using luminosity-width and -color empirical relations. However, there is a family of subluminous SNIa, also known as 1991bg-like SNIa [1], that are not standardizable and therefore are not useful for cosmology [2]. The most accepted picture is that these objects are physically different to ‘normal’ SNIa, but it is not known in detail whether the difference comes from the explosion mechanism, or from another progenitor scenario (subChandra explosions), or even other effects (asymmetries, viewing angle…). The goal of this master thesis is to define the main peculiarities of 91bg-like SNIa compared to ‘normal’ SNIa, from a sample of 91bg-like SNIa with unpublished photometric and spectroscopic observations. The student will have to develop analysis and visualization tools in python, and learn how to use the light-curve fitter SNooPy [3] to obtain the main observational properties.

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Implementation of a Pound-Drever-Hall laser frequency stabilization technique
Miquel Nofrarias

The Pound-Drever-Hall (PDH) is a laser frequency stabilization technique used as an essential part in all gravitational wave detectors. The basic idea behind its standard implementation is to use a Fabry-Perot cavity to measure the laser frequency noise to then feed back this measurement into the laser to suppress frequency fluctuations. The Gravitational Astronomy group at the Institut de Ciències de l’Espai (ICE-CSIC) has provided the Data and Diagnostics Subsystems of LISA Pathfinder, a precursor mission launched in December 2015, which has successfully measured
the residual acceleration of two free-falling test masses in space down to the 5 x 10-15 m/s2/Hz in the milliHertz band.

A particular interesting challenge arising in LISA and other fundamental physics space missions is the high stability control of temperature in the very low-frequency range (below the milliHertz). Our group is currently developing the techniques with potential impact in these future missions. For that purpose, we are investigating temperature sensing by means of phase locking to optomechanical resonators. The candidate will work in the implementation of the Pound-Drever-Hall technique that will be used to stabilize the frequency of the laser to the resonator, acting as an optical cavity. The student will work in an optical experiment and will implement the control loop scheme to suppress the laser frequency noise.

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Magnetic-induced forces in the LISA free falling test masses
Miquel Nofrarias

Gravitational waves are a prediction of Einstein’s General Relativity recently detected by the on-ground laser interferometers LIGO. LISA (Laser Interferometer Space Antenna) is an ESA mission with expected launch in 2034 aiming to detect gravitational radiation by putting three satellites in heliocentric orbit separated 2.5 million km one from each other, forming a triangle. The Gravitational Astronomy group at the Institut de Ciències de l’Espai (ICE-CSIC) has provided the Data and Diagnostics Subsystems of LISA Pathfinder, a precursor mission launched in December 2015 that successfully proved the key technologies to reach the purest free-fall in space to the date, i.e. down to the sub-femto-g. Our group led the analysis of the magnetic diagnostics onboard. A particular interesting mphenomenon to study in this context is the effect of magnetic induced kicks in the free falling test mass. An effect with interest for LISA and other future gravitational wave detectors. The student will work on the analysis of the LISA Pathfinder data and characterize the observed magnetic induced kicks in the in-flight times series. He/she will study these effects analytically and numerically by means of FEM models.

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Implementation of high stability thermal control system
Miquel Nofrarias

Space instrumentation requires precise phases of analysis and testing of the functionality and performance of developed technology. Most of these require at some point performance tests at different and stable temperature environment’s in vacuum. Depending on the instrument circumstances, this can turn out to be a complicated or tedious task, since vacuum chambers are of limited size (in order to host the device-under-test (DUT) and the testing equipment) and are keen to high temperature gradients. Being so, instrumentation for vacuum requires of special design parameters. For this thesis, we propose the development of a heater-cooling + sensors system, using a PID control loop to achieve thermal stabilities in the mK range (or higher). For this, the student will study and analyze existing actuators and sensors, and implement PID control using software-based tools. In addition, the thermal control system will be put into test inside a vacuum chamber, for which thermal shields will need to be designed.

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Data and model driven machine learning for exoplanet characterization
Guillem Anglada-Escudé

Characterization of exoplanets requires high instrumental precision as well as combining measurements from very different sources in a common framework. In addition to this, numerous instrumental and astrophysical degeneracies exist so interpreting this high quality data requires holistic and unbiased techniques to combine all the data consistently. Although we can simulate most of the complexity of the observations, these degeneracies are often difficult to predict a priori, creating all sorts of false negative and false positive detections of exoplanet features.

To account for this, and to accommodate the increasing complexity of astronomical datasets, we will implement data and model driven machine learning techniques. Instead of predicting all the cross dependencies a priori, we will use deep neural networks to identify exoplanetary features in time-series (true Doppler signals, true transit signals) and on spectroscopic observations such as the ones that are being obtained from ground based and space based observatories. This project will work with both synthetic and real observations from ground and space based observatories. Detailed knowledge of machine learning is not required, but good coding skills (especially in Python, which is the main coding language for machine learning techniques) are strongly recommended.

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Validation of the prototype level-2 flooding detector operator for ESA's HydroGNSS mission
Estel Cardellach

HydroGNSS is the second ESA Scout mission, a satellite that will provide measurements of key hydrological climate variables, including soil moisture, freeze–thaw state over permafrost, inundation and wetlands, and above-ground biomass, using a technique called Global Navigation Satellite System (GNSS) reflectometry. HydroGNSS funding has now been secured, and it shall be launched in 2024. ICE CSIC/IEEC is part of the proposing and developing team, in charge of --among other aspects-- developing, implementing and validating the operator that will retrieve Earth surface flooding conditions from the electromagnetic measurements.

HydroGNSS will have the unique capability to measure and download to Earth GNSS-R measurements at much higher sampling rate and preserving the information embedded in the phase of the electromagnetic field. These aspects open the door to new retrieval techniques, at much higher spatial resolution. The Earth Observation group at ICE-CSIC/IEEC has developed an initial algorithm that uses phase information to detect flooding. This algorithm or its evolution will become the operational level-2 operator, this is, the official mission algorithm for inverting the electromagnetic records into geophysically meaningful variables. The student will contribute towards the validation of the flood detection algorithm using existing GNSS-R data from already orbiting satellites and other sources of information.

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Analysis of the coincidences between ROHP-PAZ observations and space-based radars and radiometers
Ramon Padullés & Estel Cardellach

The Radio Occultations and Heavy Precipitation aboard PAZ satellite (ROHP-PAZ) is an experiment that had the objective to test, for the first time, the capability of the Global Navigation Satellite System (GNSS) Polarimetric Radio Occultation (PRO) technique to sense precipitation. Led by the Institut de Ciències de l’Espai (ICE-CSIC,IEEC) and on orbit since February 2018, the results of the analyses of first years of data have demonstrated that PRO are not only able to sense rain, but also to provide information of the vertical cloud structures.

With the objective to continue with the validation of the PRO technique and exploit its applications, the aim of this project is to analyze the numerous coincident measurements between the ROHP-PAZ observations and radars and radiometers. The NASA’s Global Precipitation Measurement (GPM) core satellite (CO) flies a precipitation radar that provides detailed information about rain and, partially, of its associated cloud structure. A significant number of coincidences have been identified between our ROHP-PAZ observations and GPM-CO, which are complemented by the numerous microwave radiometers also aboard GPM-CO and from other satellite platforms.

This project will consist on analyzing the coincidences and infer relationships between the different observations, with the objective to characterize the vertical structure of the ROHP-PAZ observations.

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Phase-noise validation measurements of radio-interferometer for spacecraft position and tracking
Serni Ribó

The Institute of Space Sciences is developing a radio-interferometer in the 10.7 GHz – 12.7 GHz range. The current development of the instrument requires the characterization of the current hardware in terms of phase delay measurements and its noise characteristics in a controlled environment.

The interferometer will be set up in our laboratory. A known signal will be injected into the different antenna ports and will be used as a calibration signal. Using post-processing techniques, the complex cross-correlation (visibility functions) obtained with the interferometer will be computed, and its stability and noise characterized. These measurements will yield the ultimate precision of the achievable phase delays. Phase closures shall be applied to the measured visibilities to determine the stability of the instrument itself. This is an experimental project.

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Planet formation in a very young stellar binary system
Josep Miquel Girart

The formation of relatively close (about 10 astronomical units, au) stellar binaries may inhibit or reduce significantly planet forma1on, because the circumstellar disk are expected to have a small radius ( about 1 au), and the circumbinary disk may not be stable and dense enough for planet forma1on. We have obtained with ALMA very high angular resolu1on and high fidelity images of the molecular gas around a well know very young binary system. ALMA (Atacama Large Millimeter Arrays) is the most powerful radio facility at millimeter wavelengths. The project will consist in analyzing the images to better understand how the accretion proceeds from the observed spiral filaments toward the 1ny circumstellar disk around the two young stars. Ultimately, we want to see whether the accre1on prices is high enough to allow planet formation at au scales.

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Modelling and correction of stellar activity effects to detect and characterize small exoplanets: simulations & algorithmic approaches
Ignasi Ribas

Stellar activity poses a major limitation to the extraction of planetary signals from radial velocities and transits. An evolving and rotating inhomogeneous star surface hampers the detection of small planets in temperate orbits and also atmospheric characterization of exoplanets using transit spectroscopy. Our ability to account for these effects is closely related to improving our understanding of stellar activity as a function of time and wavelength. This project will develop methodology to retrieve planetary signals from data affected by activity. One of the main tools will be the StarSim code, which is capable of accurately simulating stellar variability effects. Among other sources, proprietary data from the CARMENES radial velocity spectrometer will be analyzed.

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Bayesian Neural Networks to characterize the clustering of galaxies in cosmological surveys
Carles Sánchez

Cosmological surveys provide 3D maps of the Universe which are used to understand its composition and evolution. In particular, these surveys measure the clustering of galaxies in combination with its weak gravitational lensing effect and provide robust constraints on the amplitude of matter fluctuations at late times. In recent years, these measurements from surveys such as the Dark Energy Survey (DES) reveal a hint of tension with the predicted value from the cosmic microwave background (CMB), in a crucial test of the validity of the cosmological model.


Imminently, the enormous amount of data from new surveys such as the Rubin Observatory LSST and ESA’s Euclid mission will lower the statistical uncertainties to greatly tighten this test and shed light into the dark components of the standard cosmological model. However, the current analysis methodologies and understanding of systematic effects is insufficient for the accuracy needed by LSST and Euclid and constitute a major roadblock against achieving that science goal.

One of the main sources of systematic uncertainties concerns the characterization of the galaxy clustering measurements. Imaging galaxy data suffers from inhomogeneities due to varying observing conditions across the observed footprint, which biases the clustering signal. Several correction methods have been used so far, some of them based on neural networks, but none of them provides a correct propagation of the underlying uncertainties in the correction procedures. In this project we will develop a scheme based on Bayesian neural networks, which provide formalism to quantify and propagate the uncertainties associated with deep neural network predictions. This new scheme will allow the correct characterization of galaxy clustering measurements for cosmological inference, and will unlock the potential of such measurements at large scales (where the corrections are most important), opening a window to study the physics of the inflationary period.

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Improving mock galaxy catalogs for galaxy surveys
Francisco J. Castander

The Cosmology and Extragalactic Astronomy groups at ICE-IFAE-PIC have a long expertise on generating mock galaxy catalogs for several large extra-galactic surveys ongoing or being in which we actively collaborate such as PAU, DES or Euclid. In order to fully exploit and interpret the observed data from galaxy surveys it is essential to produce mock galaxy catalogues since they can help in a variety of ways. They are useful to design and calibrate galaxy surveys. They can help to study selection effects, to calibrate errors and explore systematic effects, to test new techniques to measure cosmological parameters or to calibrate cluster finders and photometric redshift estimators.

Accurately reproducing observed distributions in simulations is mandatory to achieve successful scientific analysis. In this Master thesis project we propose to apply in a novel way a method to estimate a continuous transformation that maps one N-dimensional probability density function distribution to another. This method will allow not only to reproduce the observed distributions but also to maintain the correlations between the observables. We will apply and validate this methodology using MICE and/or Euclid simulations.

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Constraining interstellar dust properties using submillimeter continuum measurements of nearby evolved stars
Ciska Kemper

Matter in galaxies cycles between the gas reservoir between the stars (the Interstellar Medium) and being locked up in stars, through star formation processes. At the end of a star's life, a large fraction of the stellar mass is returned to the Interstellar Medium enriched with the elements produced in stellar nucleosynthesis. Molecules and dust particles are main constituents of these stellar ejecta. The Nearby Evolved Stars Survey (NESS) is targeting a sample of nearby old stars that are currently undergoing mass loss. Observations with the James Clerk Maxwell Telescope and other submillimeter facilites allow us to study the dust and gas content of these stellar ejecta. In particular, an excess continuum emission at 850 micron where typically cold dust emits has been discovered using data from the SCUBA-2 bolometer. This excess emission has been interpreted as a cold dust reservoir which cannot be detected at shorter wavelengths.

The student will work with the NESS team to apply a data reduction pipeline to the SCUBA-2 data from the JCMT, and further study the the anomalous cold dust emission. The result may be an observational recharacterization of the dust opacities at these wavelengths, which may have far-reaching implications on dust mass determinations everywhere in the universe. In particular, if dust opacities are typically underestimated, dust masses will be overestimated.

At high redshifts, submillimeter continuum emission is often the only tracer available, and the derived dust mass determinations are used to characterize key properties of galaxies, such as the star formation rate -- a driver of galaxy evolution.

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Alternative gravity and early-time cosmology
Sergei D. Odintsov, Emilio Elizalde

Although general relativity is the simplest approach to gravity, it is not the only one. Higher order extensions of Einstein gravity play important roles in various areas such as cosmology, the early universe or quantum gravity. An alternative, known as scalar-tensor theories, goes back to the early 1960s and is the work of physicists Robert Dicke and Carl Brans, so that usually it gets the name of Brans-Dicke theory. Another family of modifications of general relativity, which appeared later but are no less famous are the f(R)-theories, where terms in higher powers of the Ricci scalar, R, as well as other suitable functions of it (as the exponential one) are introduced, has also become very popular. The new theories may have important implications in early-time cosmology, both for inflationary models and for the alternative bounce models. All this has given rise to a wide research field.

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Unified universe history from modified gravity
Sergei D. Odintsov, Emilio Elizalde

According to observations, the expansion of the universe is accelerating, but at a very gentle pace. The only way to account for this in general relativity is to include a cosmological constant, an extra value in the equations that has an incredibly small, but non-zero, value. That feature of the cosmological constant troubles most physicists because it seems incredibly unnatural. If dark energy had almost any other value, the expansion of the cosmos would have torn apart the cosmos long ago, leaving it unable to support life (including anyone who could observe it), and yet it is not perfectly zero, either. An alternative to model this behavior is to modify general relativity and use, e.g., f(R) theories. Some of them are able to connect the present accelerated expansion of the universe with the one that gave rise to inflation in its earlier history. They may be also able to describe the different intermediate epochs of the universe evolution thus providing a unified perspective of the whole universe history.

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Testing the nature of gravity with Black Holes
Michele Lenzi, Carlos Sopuerta

The detection of gravitational waves (GWs) gave great impulse to the possibility of observing strong and quantum gravity effects in Black Hole (BH) systems. At the moment we can only affirm that the Schwarzschild solution is not wrong if compared to the data, but a number of future experiments is promising to reach much higher levels of sensitivity and probe different frequency ranges and larger redshifts. For the first time over the last century, possible anomalies pointing at new physics and giving insights on the nature of the gravitational interaction and BHs may be detected. Various alternative descriptions of BHs have been developed with the aim of solving some of the most puzzling issues of gravitation, central singularity and information loss paradox and the related no-hair theorem among the others.

 

As usual in physics, a lot of information can be extracted through scattering experiments. Within this framework the quasi-normal modes (QNMs) and greybody factors play a fundamental role. The first are the dissipation modes of a perturbed BH and they seem to be deeply related to the nature of the BH itself. This is why they are considered as the characteristic oscillation modes of the BH. Furthermore, they are seen to dominate the ringdown gravitational waveforms at late time so that they are among the preferred candidates to host possible deviations from the general relativistic description. On the other side, the greybody factors encode the deviation of Hawking radiation from the pure black-body one, or in other words, the percentage of Hawking radiation which could reach us after scattering through the potential barrier surrounding the BH. Again, these quantities are intimately connected to the parameters describing the BH.

Therefore, a deep investigation of QNMs and greybody factors in different physical situations (such as possible exotic compact objects) and with different tools (both purely theoretical and numerical) offers a rich playground to test the quantum nature of gravity, no-hair theorems and alternative theories of gravity among other things.

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A study of stellar noise and stellar rotation
Fabio del Sordo

Photometric studies of stars are a crucial tool to understand the variability of stellar radiation, provide insights on magnetohydrodynamical processes occurring in the stars, and for detecting exoplanetary transiting between us and their host stars. Variations of stellar luminosities show up in stellar light curves and can reveal both noisy fluctuations in stellar radiation and transiting exoplanets. Thanks to time series of photometric data we can measure the period of rotation for a star. This problem may appear easy, but it is in fact quite complex because every measure of rotational period relies on features appearing on stellar surface like stellar spots or faculae. The occurrence of these features is currently not understood and it is difficult to predict, and so it is their life time. We therefore need to employ new analysis techniques so to analyze time series and extract useful informations on stellar photometry.

We will analyze data from the Nasa Kepler mission, that observed several thousands of stars. We will concentrate on some M dwarfs from the Kepler catalogue, some sun-like stars, and we will also analyze solar data. We will use a new time series analysis technique base on multifractal modelling of data. This multifractal technique allows identifying time scales with a model-free approach, and provides information the noisy beheaviour of data sets. We will compare our results with previous findings, and depict the time evolution of noise in these different kind of stars.

  • Get familiar with the multifractal technique, both numerically and
    mathematically (3 weeks)
  • Find and download the data (3 weeks)
  • Run the analysis (2.5 months)
  • Write up our findings (2 months)
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Cosmology and Galaxy Surveys, emulating the growth of structure
Martin Crocce
The Cosmology and Extragalactic Astronomy group at ICE is engaged in a very ambitious and competitive international research program focused on the understanding of the cosmic acceleration (also known as dark energy) and the growth of large-scale structure in the Universe.
Probing the nature of dark energy is at present one of the fundamental problems in modern Cosmology, and the field is very active worldwide. There are several large galaxy surveys ongoing or being planned, with emphasis in various probes of dark energy (type-Ia supernovae, weak gravitational lensing and galaxy clustering). Our group is very active in several of them: PAU, DES, ESA/Euclid and DESI (*).
 
These surveys trace the growth of structure by correlating the position and shapes of millions of galaxies across huge distances and redshifts. The resulting correlation functions are compared to models of the Universe, to constrain cosmological parameters such as matter density, neutrino mass, dark energy parameter, etc. One key aspect of the analysis is being able to connect underlaying theories and predictions with the direct measurements, while scanning over all possible theory parameters of interest. 
 
In this Master thesis project we propose to investigate and use a state-of-the-art technique that is being widely used in  other areas of physics based on Machine Learning and Gaussian process that allows to produce such predictions very fast after training the software at specified points in parameter space (e.g. a latin hypercube). This kind of developments will be critical in the near future. In parallel to this we will overview the field of observational cosmology, learning about numerical simulations and data analysis, while interacting with other students and postdocs in our group (about 10).
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Neutron stars as a laboratory for dense matter
Cristina Manuel & Laura Tolós

Compact stars, and more particularly neutron stars, are a unique laboratory for testing matter under extreme conditions. Over the past years a particular effort has been invested in studying different scenarios for the dense phases of matter in the core of neutron stars, from quarks to hadrons at high densities. The final aim is to understand neutron star observables, such as the mass, radius, magnetic fields or rotation, in terms of a plausible scenario for its interior.

For this purpose, theoretical approaches based on effective field theories for hadronic and quark matter have been developed in our group. The master thesis proposed aims at following the study of the interior of neutron stars by applying the previously developed theoretical frameworks to obtain the equation of state and transport properties of dense matter in the core of neutron stars. With these ingredients, we will be able to address the mass and radius of neutron stars as well as the dynamical properties of neutron stars, going from rotation to the effect of magnetic fields onto neutron stars.

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How do brown dwarfs and giant exoplanets emit in radio?
Daniele Viganò

Exoplanetary sciences are living a boom, mostly thanks to the traditional transiting and radial velocity detection methods, and the increasingly improving atmospheric characterization. A more unusual way we expect to study them is their emission at low radio frequencies, which is expected since Jupiter and other Solar planets are also radio-emitters. Intense campaigns to detect such dim but informative emission are on-going, embracing the largest planets and their sub-stellar cousins, the brown dwarfs. Studying their radio emission gives direct insights on the magnetic properties of the system, which are very important but still highly unconstrained for exoplanets.

The proposal is on one side to identify among these sub-stellar objects the most promising radio-emitter candidates in order to propose radio observations with different international radio telescopes. This will imply a throughout investigation of the existing literature and archival data of past observations.

On the other side, one aim is to predict how we expect them to emit, making use of theoretical arguments and running a public numerical code, ExPRES.

The work will be performed at ICE, within a new young group, IMAGINE, consisting of two post-docs and 3 PhD students, one of which will work in close contact with you. Please, contact us for any doubt and join us!

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The delivery of water and organics to Earth from chondritic materials available in the protoplanetary disk
Josep M. Trigo

The transport of water and organics to our planet occurred from sequestration of these volatile phases at an early stage of the formation of planetary embryos. The study of chondritic meteorites can be complemented with the interpretation of modern dynamic studies of the mixing of primordial materials available in proto-planetary disks.

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Eclipsing binary systems
Juan Carlos Morales

Eclipsing binary stars are fundamental laboratories in stellar astrophysics because they can provide the masses and radii of stars with a precision of a few percent, which can be later used to compare the predictions of stellar theoretical models. Our research group has a lot of experience on the analysis of eclipsing binary stars. Currently, we are conducting photometric and spectroscopic observations to revise the parameters of several systems and to derive the properties of some new ones that have been found using TESS data. Besides, we are measuring eclipse timings from TESS and ground-based data. These eclipse timings can be used with several purposes: to investigate the presence of third bodies in the system (planets or stars), to test General Relativity, or to infer the internal properties of the component stars. In this project, we expect the student to make use of these data to study the properties of such systems.

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