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2023 / 2024

Friday at ICE-CSIC means #PizzaSeminar!

These seminars have been going on for 10 years now. We gather at the patio of the institute to eat pizza after the seminar as a nice way of ending the week. Since the last few months, the seminars are a hybrid event and we're happy to see you every Friday at 12 pm online.


Thermal analysis & Hypatia

Laura González Llamazares (Radian Systems)

Thermal analysis is a critical step in spacecraft design, ensuring that components function optimally in the extreme conditions of space. This seminar will provide an overview of the thermal analysis process, and will demonstrate a cutting-edge cloud-based tool that simplifies the thermal analysis process for space missions, showcasing its user-friendly interface. Additionally, we will introduce Hypatia, an all-women crew analog mission dedicated to advancing Martian research and outreach, promoting space exploration, and fostering scientific vocations, especially among girls and young women.


Constraints on the dense matter equation of state from young and cold isolated neutron stars

Alessio Marino, Clara Dehman, Konstantinos Kovlakas, Nanda Rea

Neutron stars are the dense and highly magnetic relics of supernova explosions of massive stars. The quest to constrain the Equation of State (EoS) of ultra-dense matter and thereby probe the behavior of matter inside neutron stars, is one of the core goals of modern physics and astrophysics. A promising method involves investigating the long-term cooling of neutron stars, and comparing theoretical predictions with various sources at different ages. However, limited observational data, and uncertainties in source ages and distances, have hindered this approach. In this work, re-analyzing XMM-Newton and Chandra data from dozens of thermally emitting isolated neutron stars, we have identified three sources with unexpectedly cold surface temperatures for their young ages. To investigate these anomalies, we conducted magneto-thermal simulations across diverse mass and magnetic fields, considering three different EoS. We found that the "minimal" cooling model, failed to explain the observations, regardless the mass and the magnetic field, as validated by a machine learning classification method. The existence of these young cold neutron stars suggests that any dense matter EoS must be compatible with a fast cooling process at least in certain mass ranges, eliminating a significant portion of current EoS options according to recent meta-modelling analysis.


Improving the Hubble Diagram on Both Axes

Erik Peterson, Duke University

Various cosmological parameters such as H0 and S8 measured using Type Ia Supernovae (SNe Ia) have been shown to be in tension with measurements from the early universe. We can improve cosmological parameter measurements and reduce scatter on the Hubble Diagram by focusing on both magnitude scatter by leveraging the near-infrared (NIR) and redshift scatter by leveraging galaxy groups. With the DEHVILS sample, one of the largest uniform NIR samples of SN Ia light curves (LCs), we measure and analyze the reduction in Hubble residual scatter as compared to the optical. Using the low redshift sample from Pantheon+ combined with a new sample from the AAT spectrograph, we obtain and average the redshifts of galaxy groups to correct for peculiar velocities and improve scatter on the Hubble Diagram. With the impending arrival of the Roman Space Telescope, which will observe in the NIR and need a well understood low-redshift anchor SN sample, we encourage further analysis on NIR SN Ia LCs and an increased effort to define more galaxy groups.


Fundamental Physics and Cosmology with the Einstein Telescope

Michele Maggiore, University of Geneva

The observation of gravitational waves by the LIGO/Virgo collaboration has opened a new window on the Universe. In this decade, however, these experiments will reach the limit of their capabilities, and a new generation of ground-based detectors is being planned. In Europe, this has led to the proposal of the Einstein Telescope. With order of magnitude improvement in the sensitivity, Einstein Telescope will explore the depth of the Universe using gravitational waves, and has the potential of triggering revolutions in astrophysics, cosmology and fundamental physics. We will give a broad overview of its capabilities and scientific targets.


From chirps to gold: colliding neutron stars as a laboratory for extreme physics

François Foucart, University of New Hampshire

Colliding neutron stars provide us with a remarkable laboratory to test the laws of physics in conditions generally inaccessible to earth-based experiments. These rare but extremely energetic events are among the few systems capable of powering gravitational waves detectable by existing ground-based observatories. The matter ejected by these mergers additionally powers a broad range of electromagnetic signals, from short gamma-ray bursts to years-long radio emission. From these gravitational wave and electromagnetic signals, we can extract information about the properties of cold matter at nuclear densities, understand the origin of heavy atomic elements such as gold and uranium, or even study the nature of gravity or the evolution of the Universe. In this talk, I will review the physics of merging neutron stars and our efforts to model these systems through numerical simulations. I will also discuss how these extreme astrophysical events are used to help us solve important open questions in astronomy and nuclear astrophysics.


The amazing geology and structure of Dimorphos: challenge or opportunity for asteroid deflection?

Josep M. Trigo-Rodríguez, Institute of Space Sciences (ICE-CSIC) & Institute of Space Studies of Catalonia (IEEC)

DART mission achieved the kinetic deflection of asteroid Dimorphos on Sep. 26th, 2022. That 151 meters in diameter is the satellite of binary asteroid (65803) Didymos. DART scientific research has revealed the structure and amazing geology of Dimorphos that points to a past of catastrophic impacts. I briefly introduce several forthcoming papers on the main results on that amazing asteroid. This talk will summarize what we learned from the DART NASA mission, and what are the next tasks to pursue with the next Hera ESA mission. We will try to answer: how difficult is deflecting rubble piles, a structure shared by most hazardous asteroids?


Who was the first to discover that our Universe expands and that it had an origin?

Emilio Elizalde, Institute of Space Sciences (ICE-CSIC) & Institute of Space Studies of Catalonia (IEEC)

Who was the first person to discover that our Universe is expanding? Edwin Hubble, obviously. According to common lore, he personally did the whole work leading to this crucial finding. Only few know, however, that Hubble never believed the Universe was expanding. He always fought the Big Bang model, considering it erroneous (for very good reasons!). Georges Lemaître, instead, is presently gaining more and more support, even obscuring Alexander Friedmann’s role. I will argue that, to deal with those slippery matters, we must start by setting up the playing table, and by carefully choosing the deck of cards we are going to play with. Having done that, an answer to the above question will be delivered. To finish, the two cosmological revolutions of the last Century will be revisited, with the aim to put the main actors in their well-deserved places.


Strong gravity beyond Einstein's gravity: from "the quantum" to "the cosmo"

Marcelo Rubio, International School for Advanced Studies (SISSA)

General Relativity (GR) is undoubtedly a fascinating theory, which has radically changed the way of understanding space, time and gravitational interactions in Modern Physics. A wide variety of experimental probes, both in terms of sensitivity and number of observations, has allowed GR to be tested in the strong gravitational regime (from gravitational-wave astronomy, electromagnetic counterparts, binary pulsar observations and radio-astronomy, among other channels). Remarkably however, the study of compact objects in GR has motivated the astrophysicist community to ask whether or not similar predictions should also be obtained from modified theories of gravity.
The purpose of this talk is to go through various aspects of gravity in theories beyond GR. Although a large family of theories of gravity has been proposed to address issues such as the nature of the cosmological acceleration, or the non-renormalizability of Einstein’s theory, a pressing question in this context would be: which one/s of them should we really worry about?
We will review two classes of modified theories. The first one, proposed by Petr Hořava in 2009, is a "quantum-motivated" prominent candidate for an ultra-violet completion of GR. This theory aims to understand gravitational interactions at the Planck scale (thus extending Einstein's proposal), but at the cost of giving up Lorentz symmetry. The second one, within the so-called "scalar-tensor" theories, is cosmology-motivated, and it aims to constrain Dark Energy models consistent with observations. After commenting on (some of) the main interesting features within these two different theories, we will comment on recent contributions, some applications and future perspectives.


Snooping around millisecond pulsars: can accretion- and rotation-powered states co-exist?

Giulia Illiano

Millisecond pulsars are old, low-magnetized, and rapidly rotating neutron stars that have recently challenged a long-standing paradigm. Typically, they are believed to shine as rotation-powered radio and/or gamma-ray sources only after a Gyr-long, X-ray bright phase of matter accretion from a low-mass companion star, which spins them up. However, transitional millisecond pulsars are binary systems that swing between radio and X-ray states on timescales as short as a few days. They have also been caught in a distinctive X-ray sub-luminous state that exhibits characteristics of both rotation- and accretion-powered pulsars. In this context, the recent discovery of coherent optical pulsations from the archetypes of transitional and accreting millisecond pulsars suggests that a rotation-powered magnetospheric process may persist even in the presence of an accretion disk. I will review some recent findings that contribute to redefining the conventional boundaries between accretion- and rotation-powered pulsars.


Cosmological constraints from two- and three-point galaxy clustering

Alexander Eggemeier

Galaxy surveys are instrumental in measuring the Universe’s geometry and the growth of cosmic structures, providing constraints that complement and are competitive with those from the cosmic microwave background and Type Ia supernovae. Despite this, current constraints from large-scale structures primarily rely on statistics describing the clustering of galaxy pairs, neglecting the rich information embedded in the more complex patterns of the cosmic web. In this presentation, I will begin by summarizing the conventional techniques for analysing galaxy clustering, highlighting the advantages of incorporating three-point information (galaxy triplets). The discussion will then focus on the challenge of accurately predicting redshift-space distortions, which are induced by the peculiar velocities of galaxies. This issue has so far limited the benefits from combined two- and three-point statistics analyses, a concern that grows as statistical uncertainties decrease with upcoming data from the Dark Energy Spectroscopic Instrument (DESI) and the Euclid telescope. I will contrast the approach currently employed in standard effective field theory methods with a model that incorporates a deeper understanding of the peculiar velocity distributions. I will demonstrate that this not only leads to a more accurate description of the data, but also significantly tightens cosmological parameter constraints, largely due to enhancements unlocked by three-point statistics.


ICE-CSIC María de Maeztu Best paper Awards 2024

Clàudia Soriano & Michele Lenzi

Clàudia Soriano: "Magnetic winding and turbulence in ultra-hot Jupiters"

Abstract: While magnetism in exoplanets remains largely unknown, Hot Jupiters have been considered as natural candidates to harbour intense magnetic fields, both due to their large masses which might empower a larger internal dynamo, and, possibly, due to their high energy budgets coming from irradiation. In this work we focus on the latter aspect and perform MHD simulations of a narrow day-side atmospheric column of ultra-hot Jupiters, suitable for very high local temperatures. Due to the high conductivity in this regime, the primary influence is the winding of the magnetic field caused by the intense zonal winds. In our study, we include a forcing that mimics the wind profiles observed in GCMs near the sub-stellar point. As a result, the shear layer generates a toroidal magnetic field, locally reaching few kG, which is supported by meridional currents. Such fields and the sustaining currents do not depend on the internal field, but are all confined in the thin (less than a scale-height) shear layer around 1 bar. Additionally, we add random perturbations that induce turbulent motions, which lead to further (but much smaller) magnetic field generation to a broader range of depths. These results enable the assessment of the atmospheric currents that are induced. Although here we use ideal MHD and the only resistivity comes from the numerical scheme at a fixed resolution, we estimate a-posteriori the amount of Ohmic heat deposited in the outer layers, which could be employed in evolutionary models for Hot Jupiters' inflated radii. We will also include the last updates of the model, which include realistic GCM profiles, non-isothermal profiles as well as real MHD, which make the models applicable for all HJs.

Michele Lenzi: "Black hole greybody factors from Korteweg–de Vries integrals: Theory"

Abstract: The dynamics of perturbed nonrotating black holes (BHs) can be described in terms of master equations of the wave type with a potential. In the frequency domain, the master equations become time-independent Schrödinger equations with no discrete spectrum. It has been recently shown that these wave equations possess an infinite number of symmetries that correspond to the flow of the infinite hierarchy of Korteweg–de Vries (KdV) equations. As a consequence, the infinite set of associated conserved quantities, the KdV integrals, are the same for all the different master equations that we can consider. In this paper we show that the BH scattering reflection and transmission coefficients characterizing the continuous spectrum can be fully determined via a moment problem, in such a way that the KdV integrals provide the momenta of a distribution function depending only on the reflection coefficient. We also discuss the existence and uniqueness of solutions, strategies to solve the moment problem, and finally show the case of the Pöschl-Teller potential where all the steps can be carried out analytically.


Optical technologies for astrophysics, Earth and planetary sciences

Felipe Guzmán (University of Arizona)

Novel technologies and measurement principles find application in areas that are paradigm-changing; not only in fundamental science, but that directly impact the global economic and political stage. Detections from ground-based gravitational-wave observatories, like LIGO and VIRGO together with measurements of their electromagnetic counterparts, have opened a new window to observe the universe’s gravitational spectrum and have reshaped astronomy and astrophysics through Gravitational Wave and Multi-Messenger observations. Plans for future observatories in space, such as LISA, are well underway with the extremely successful LISA Pathfinder mission and the formal adoption of ESA. Moreover, GRACE follow-on continues GRACE’s legacy of providing information regarding climate change and our planet’s geo-dynamics through valuable observations of the Earth’s gravitational field, and developments are well advanced for subsequent missions both in the USA and Europe.


A link to the past: Searching for wandering intermediate-mass black holes in the Milky Way

Julen Untzaga (ICE-CSIC)

Intermediate-mass black holes (IMBHs), with masses in the range 100 – 1.000.000 M⊙, are the link between stellar-mass and supermassive black holes (SMBHs) and the possible seeds from which SMBHs in the early Universe grew via accretion and mergers. Theoretical models support that a fraction of these IMBH seeds did not grow into SMBHs, and instead remained in the intermediate-mass regime up until z = 0. Therefore, characterizing the properties and formation mechanisms of the seed IMBHs found in the local Universe is essential for a complete understanding of the IMBH and SMBH populations throughout cosmic history. My research focuses on improving the general understanding of the long predicted wandering black hole (WBH) population in the Milky Way (MW) by combining both observational and computational work. On the observational side, I have utilized data from the Pan-STARRS-1, Hyper Suprime-Cam, and Gaia surveys to search for hyper-compact clusters of old, low-metallicity stars in the MW halo, which are potential indicators of the presence of WBHs. On the computational side, I have employed the L-Galaxies semi-analytic code that is built upon the dark-matter simulation Millenium-II to characterize the WBH population in MW-type galaxies at z = 0. By integrating observational and computational techniques, this work aims to contribute to a comprehensive understanding of the WBH population in the MW and its implications for the broader field of astrophysics.


Exploring the Universe with LISA

Carlos F. Sopuerta (ICE-CSIC, IEEC)

LISA, the Laser Interferometer Space Antenna, will be the first space mission ever to survey the Universe by detecting low-frequency gravitational waves. The LISA mission, led by the European Space Agency (ESA) in collaboration with the US National Aeronautics and Space Administration (NASA), has recently being adopted and enters the implementation phase with a launch expected in 2035. The science of LISA is very broad and has implications for Astrophysics, Cosmology, and Fundamental Physics. In this talk, I will describe the main characteristic of the LISA mission, its science case including opportunities for multimessenger and multiband astronomy, and the main scientific challenges ahead of us.


Meta-materials and Meta-surfaces: Exploring Applications and Research Opportunities in Radio Astronomy

Arshad Karimbu Vallappil (ICE-CSIC)

Metamaterials (MTMs) are artificial electromagnetic structures with unconventional properties not typically found in nature. These synthetically engineered composite materials possess a unique ability to control electromagnetic waves across various spectra, including visible light and microwaves, in unprecedented ways that cannot be achieved with natural materials. Beyond their electromagnetic capabilities, these materials are poised to redefine technology, addressing challenges such as size, weight, bandwidth, tunability, and reconfigurability. This exploration provides a comprehensive overview of MTMs and meta-surfaces (MTS), covering fundamental concepts, structures, and applications. It emphasizes their integration into antennas, beamforming networks, radio frequency components, and beam shaping analyses, highlighting their potential as game-changers in technology innovation.


Isolated pulsar population synthesis with simulation-based inference

Celsa Pardo Araujo (ICE-CSIC, IEEC)

Many challenges in astrophysics involve the task of constraining free parameters of a physical model to match the observed reality. Often, these models are highly complex, making Bayesian inference through traditional approaches impractical due to intractable likelihoods. To overcome this issue we can use so-called simulation-based (or likelihood-free) inference. This approach is particularly powerful when combined with deep learning, wherein a neural network learns to map from the simulated data onto the posterior distribution of the underlying parameters. In this presentation, I will provide an overview of simulation-based inference methods and explore the possibility of using one of these within the context of pulsar population synthesis to constrain the magneto-rotational parameters of the isolated pulsar population in the Galaxy. Specifically, I will present recent results that show how we successfully train neural networks on simulated data to infer the initial period distributions and magnetic-field properties of neutron stars without the necessity of assuming a simplified likelihood.


White dwarf stars in the Gaia era

Maria Camisassa (Universitat Politècnica de Catalunya)

White dwarf stars are the most common endpoint of stellar evolution. Therefore, these numerous, old and compact objects provide valuable information on the late stages of stellar evolution, the physics of dense plasma and the structure and evolution of our Galaxy. The ESA Gaia space mission has revolutionized this research field, providing multi-band photometry, synthetic spectra, proper motions and parallaxes for these stars. Specifically, this mission has allowed the identification of nearly 360.000 white dwarfs, revealing some unexpected features on the white dwarf sequence in the color-magnitude diagram, and raising new questions on the nature of these stars. Furthermore, this data combined with spectroscopical and spectropolarimetric observations, have provided new information on chemical abundances and magnetic fields of these stars, demanding a thorough understanding of their physical processes. In this talk, I will summarize these questions and I will describe possible explanations for them, on the basis of detailed theoretical evolutionary models and population synthesis studies.


The Magnet alliance: bringing astronomy to the classroom to fight scholar segregation

Alba Calejero (ICE-CSIC Communications & Outreach office)

School segregation is a growing problem throughout Europe that tends to create schools with a very high socioeconomic complexity. We’ll present our experience within the Magnet alliance, in which the Institute of Space Sciences (ICE-CSIC) collaborates in the 2021-2025 period with the Gabriel Castellà i Raich school in Igualada (Barcelona province, Spain). Advised by an expert in didactics, we have co-created with teachers and implemented inquiry-based astronomy activities for 3 to 11 year-old students. The goal is to provide the school with added pedagogical and educational value, which can attract local families, in order to balance the demographics of the student body and promote inclusion in current and future society. In this talk, we will present the activities developed during the first half of the program, plans for the future and lessons learnt.


Explosions of white dwarfs as novae and their role in the origin of Lithium-7 and cosmic rays

Margarita Hernanz (ICE-CSIC, IEEC)

White dwarf stars in binary systems can explode as novae and as type Ia supernovae. Nova explosions are the result of hydrogen burning on top of the white dwarf, leading to mass ejection but not disrupting the whole white dwarf, contrary to type Ia supernova explosions, that affect the whole white dwarf star. Nova ejecta contribute to the origin of some interesting isotopes in the Universe, like Lithium-7, whose origin is in fact not yet clear. The production of Lithium-7 and other isotopes in novae implies the emission of gamma-rays in the MeV energy range, only detectable with satellites like the current INTEGRAL from ESA and the future COSI from NASA. Last but not least, mass ejection from novae is also responsible of the origin of cosmic rays, because novae can accelerate protons and electrons that produce High-Energy (HE) gamma-rays in the GeV range - detected from space with the NASA Fermi satellite in several novae - and Very HE (VHE) gamma-rays, detected from ground with current Cherenkov telescopes like MAGIC and HESS in the RS Oph nova.


Nuclear Physics from Neutron Star Mergers

David Tsang (University of Bath)

Neutron stars are the universe’s best natural laboratories to study dense nuclear matter. At high densities and low temperatures inaccessible in terrestrial collider experiments, neutron stars host the most extreme matter in the universe. Different regions of neutron stars will probe different physics, with some observables dominated by the poorly understood physics at supranuclear densities, while others can be used to constrain properties of nucleonic matter, such as the nuclear symmetry energy. I will discuss our latest work on Resonant Shattering Flares, multimessenger signatures which can be used as a powerful constraint on nuclear physics. Studying the spectrum of asteroseismic modes in a neutron stars can provide probes at different densities, and hence of different physics.


The ngVLA, its science cases, and the current role of Mexico

Alfonso Trejo Cruz, Instituto de Radioastronomía y Astrofísica (IRyA-UNAM)

The ngVLA, led by the National Radio Astronomy Observatory (NRAO), will be the largest radio interferometer ever built in the northern hemisphere. With more than 200 antennas distributed across the US, Canada, and Mexico, the array will reach spatial resolutions and sensitivities without precedents. The ngVLA will open a new window on the universe through ultra-sensitive imaging of spectral lines and continuum emission with milliarcsecond resolution. We will summarise the main science goals, from the initial conditions of planetary systems to understanding the origin and evolution of black holes. For Galactic science, synergies between ongoing efforts with the current VLA and the ngVLA will be provided, in particular for AGB stars. In the second part of the talk, we will describe the current ngVLA efforts being pursued in Mexico. The MID Array of the ngVLA will provide some of the longest baselines of the new observatory, with a large fraction of those enabled by the antennas in Northern Mexico. We will discuss the work to select the final MID sites in Mexico, including synthetic observations to characterise the array performance. We’ll finalise with the observatory designs that Mexico is leading, such as antenna base foundations, antenna site layouts, and antenna supporting buildings. Finally, we outline the next steps in the coming 2 years, including workshops and conferences.


The wickedly cool and bursting stellar zombies

Nanda Rea, ICE-CSIC & IEEC

I will give a very general review on our group's research on neutron stars in a cauldron of boiling multi-band observations and theoretical simulations. I will then report on two recent results: the first related to a new creepy class of periodic radio bursters, and the second to a few super cold rotating jack-o'-lanterns... and how those are changing our understanding of these wicked stellar zombies.


Current flow in pulsar magnetospheres and the role of twist

Kostas Gourgouliatos, University of Patras (Greece)

He will discuss some properties of the axisymmetric force-free pulsar magnetosphere focusing on the inner edge of the current sheet, the so-called Y-point. While it is usually postulated that it is located at the intersection of the equator with the light-cylinder, we propose that it is energetically favourable to be located within the light-cylinder. Should this be the case, the spin-down dipole magnetic field is likely to be an overestimate of the star's actual field. Furthermore, he will discuss the impact of currents flowing within the closed field lines: in this case, the spin-down power is higher than the one corresponding to the dipole field and for sufficiently high twists the field adopts the structure of a split monopole.


B-field Orion Protostellar Survey: Magnetized Envelopes in Orion

Bo Huang (Institute of Space Sciences, ICE-CSIC)

B-field Orion Protostellar Survey (BOPS) used ALMA to observe 870 um dust polarization toward 61 young low-mass protostars in the Orion molecular clouds. Its main objective is to investigate the role of B-fields from 400 to several thousands au scales, corresponding to the size of molecular envelopes about the youngest (predominately Class 0) protostars. This survey uniformly probe the B-field structure within the envelopes surrounding the protostars to help remove biases based on resolution and different environments. Both the polarization and outflow were successfully detected emission in 56 sources. In 16 of them the polarization is likely produced by self-scattering, most of these are Class 0, suggesting that grain growth appears to be significant in disks in earlier protostellar phases. For the rest sources, the dust polarization traces the magnetic field, whose morphology can be approximately classified into three categories: standard-hourglass, inverted-hourglass, and spiral-like morphology. Two-fifth of the sources exhibit a mean magnetic field direction approximately perpendicular to the outflow from several hundreds to thousands au scales, but for the rest of protostars, this relative orientation appears to be random, probably due to the complex set of morphologies observed. Furthermore, the protostars are classified into three types based on the velocity gradient traced by C17O (3--2): PerpType (gradient perpendicular to outflow), RandType (gradient randomly aligned with outflow), and UnresType (unresolved gradient, less than 1 km/s/arcsec). In PerpType, field lines are preferentially perpendicular to the outflow, and along the collapsing direction, most of them are inverted-hourglass, suggesting that magnetic field have been overwhelmed by gravity. The spiral-like magnetic fields are associated with sources with large velocity gradients, indicating that the rotation motions is strong enough to twist significantly the field lines. All the sources with a standard-hourglass field morphology show no significant velocity gradient probably due to the strong magnetic braking.


Pulsar science with the MeerKAT radio telescope

Miquel Colom i Bernadich (Max-Planck-Institut für Radioastronomie)

Radio pulsars are highly magnetised, fast-rotating neutron stars born from the collapse of massive stars at the end of their life cycle. Pulsar timing is the technique of modelling a pulsar’s rotation down to every single revolution and comparing it with the times of arrival of radio pulses as recorded by telescopes on Earth. When found in binary systems, this technique is used to track the orbital motion of pulsars in their system. This allows us to investigate a wide range of fundamental physics and astrophysics, such as light propagation physics, alternative theories of gravity, equation of state models of neutron stars and binary evolution. The MeerKAT radio telescope in South Africa is currently the most sensitive facility in the Southern Hemisphere, constituting a great leap forward in the search for and study of pulsars in the Southern Sky. In this talk, he highlights recent science results from pulsar observations with MeerKAT and showcase some of the currently ongoing science projects, such as the TRAPUM pulsar surveys and the RelBin pulsar timing programme.


Closing down the observation gap on millisecond to second timescale relativistic X-ray and radio transients

Sujay Mate, Tata Institute of Fundamental Research (TIFR), Mumbai

Over the past few decades, transient astronomy has boomed with discovery of different types of transient phenomena (e.g. Gamma-ray Bursts — GRBs, Fast Radio Burst — FRBs, compact binary coalescence in gravitational waves — CBCs). Most of these transients are highly relativistic events and key to understanding them is to do multi-wavelength and multi-messenger observations. In this talk, I will present our efforts to build instrumentation to detect milliseconds to second timescale relativistic transient phenomena at X-ray and radio wavelengths. I will present the proposed Indian mission Daksha that aims to detect GRBs and electromagnetic counterparts of GW events. Once launched, Daksha will be one of the most sensitive X-ray/gamma-ray telescope. In particular, I will talk about the prospects of measuring hard X-ray polarisation of GRBs using Daksha, which is a key to understanding emission mechanisms and geometry of GRB jets. For this analysis, we have carried out detailed simulations and have developed a pipeline to measure the polarisation. We estimate that Daksha will have Minimum Detectable Polarisation of 30% for a GRB with fluence 10^-4 erg/cm^2. With this sensitivity, Daksha will be able to measure polarisation of at least five GRBs per year. Towards the end, I will briefly talk about the CHIME/Slow search, that involves our novel efforts to detect radio transients at seconds timescale with the Canadian Hydrogen Intensity Mapping Experiment (CHIME) radio telescope. This parameter space is as-yet unexplored and could harbour interesting transients such as "slower" duration or extremely scattered FRBs, radio counterparts of GRBs or binary neutron star mergers, flaring stars, magnetized white dwarfs and radio emission from X-ray binaries.


Supporting a culture of public engagement at ICE-CSIC

Jorge Rivero, Institute of Space Sciences (ICE-CSIC)

Astronomy allows us to study the far reaches of the universe but also gives us a different perspective on our planet, showing us its fragility and fostering a sense of global citizenship. In this sense, astronomy is in a unique position to engage citizens on scientific topics, make them reflect on their place in the universe, and encourage their critical thinking. Several studies show that citizens consider that professional scientists are best qualified to explain the impact of scientific and technological developments on society. And even though astronomers are quite involved in public engagement in comparison with scientists in other fields, they often rely on individual endeavours with approaches with little engagement and/or lacking goals for deeper interaction beyond one-off events. In this respect it is important to work together with the institution's communication professionals in our common journey to share the wonders of the universe with society while we establish a culture of public engagement at the institution. In this talk, he will present his thoughts on why public engagement is important, why researchers should get involved and work together with science communication professionals as well as showcase the opportunities we offer through ICE-CSIC's Communication and Outreach Office to participate in communication and public engagement activities.


The MagMAR project: First Results

Paulo Cortes, National Radio Astronomy Observatory (NRAO)

The process governing the formation of high-mass stars, those exceeding eight solar masses, remains enigmatic, despite their pivotal role in regulating chemical, radiative, and energetic feedback within our galaxy. Of all the pertinent parameters influencing high-mass star formation, the magnetic field stands as a predominantly uncharted territory, its presence inevitable yet exploration limited. Endeavoring to bridge this knowledge gap, the MagMAR project leverages the unparalleled mapping capabilities of ALMA. In this presentation, he will introduce the MagMAR project and showcase its initial results.


Is cosmic expansion really accelerating?

Enrique Gaztañaga, ICG (UoP), ICE-CSIC & IEEC

He will show that deceleration (and not acceleration) is the correct interpretation for current measurements of cosmic expansion. The concept of cosmic acceleration, q, that we commonly used is based in the comoving distance. This is a 3D space-like coordinate, which corresponds to distance between events that can not be observed and are not causally related. For a correct interpretation cosmic expansion should be measured using the distance between (4D null) causal events. This is implemented here using a new definition, q_E, for cosmic acceleration. We present a comparison of the two alternative definitions, q_E and q, against data from supernovae (SN) and radial galaxy/QSO clustering (BAO). The standard q analysis reproduces some known tension between SN and BAO, but this tension disappears for q_E, indicating that this definition better fits observations. Data clearly shows that cosmic expansion is decelerating so that cosmic events are trapped inside an Event Horizon, like in the interior of a Black Hole (BH). Rather than a new form of dark energy or modified Gravity, this corresponds to a boundary force that causes friction, i.e. an attractive force, similar to a rubber band that prevents further expansion.

Find previous #PizzaSeminars at our YouTube channel