Past Pizza Lunches

Number of entries: 153

29
November 2019

Black hole in globular clusters


Start: 12:15h
Speaker: Mark Gieles
Place: Alberto Lobo room

Globular clusters (GCs) are the outcome of the earliest phases of star and galaxy formation in the Universe. Their high densities foster the formation and hardening of binary black holes (BHs) that can merge via gravitational wave in-spiral. The contribution of this `dynamical channel' to gravitational…
Start: 12:15h
Speaker: Mark Gieles
Place: Alberto Lobo room

Globular clusters (GCs) are the outcome of the earliest phases of star and galaxy formation in the Universe. Their high densities foster the formation and hardening of binary black holes (BHs) that can merge via gravitational wave in-spiral. The contribution of this `dynamical channel' to gravitational wave detections - relative to other channels - is not understood, because it sensitively depends on the poorly constrained BH natal kicks and the unknown properties of infant GCs. I will present results of efforts to infer the BH content of Milky Way GCs by comparing dynamical mass models to kinematics and star counts. We find the signal of a BH population in several Milky Way GCs and I will discuss the implications of these findings for the BH merger rate across cosmic time.
22
November 2019

Magnetic environment and experiments on-board LISA Pathfinder


Start: 12:15h
Speaker: Juan Pedro López Zaragoza
Place: Sala Alberto Lobo (ICE building, Campus UAB)

The differential acceleration measurement between two free-falling test masses on-board LISA Pathfinder is limited in the low frequency regime by force noise applied to the test masses. Several effects can contribute as force noise on the inertial masses and, amongst them, magnetically-induced forces…
Start: 12:15h
Speaker: Juan Pedro López Zaragoza
Place: Sala Alberto Lobo (ICE building, Campus UAB)

The differential acceleration measurement between two free-falling test masses on-board LISA Pathfinder is limited in the low frequency regime by force noise applied to the test masses. Several effects can contribute as force noise on the inertial masses and, amongst them, magnetically-induced forces are precisely one of the effects limiting the performance of the instrument in the milliHertz band. The origin of this disturbance is the coupling of the residual magnetisation and susceptibility of the test masses with the environmental magnetic field. In order to fully understand this term of the noise model, a set of coils and magnetometers are integrated as a part of the LISA Pathfinder diagnostics subsystem.
In this talk we will explain which are the different magnetic experiments we have carried on board LISA Pathfinder in order to extract the magnetic parameters that characterise LISA Pathfinder's test masses. Moreover, we will also give a complete overview of which was the magnetic field on-board the satellite during mission operations and the effects it had on the mission performance. We will finally describe how, by analysing the movement of the test masses during magnetic experiments, we can extract not only information about their magnetic properties, but also about the environment that surrounds them. We also provide the magnetic contribution to the LISA Pathfinder noise budget.
 
15
November 2019

Apadrina un carolingi


Start: 12:30h
Speaker: Serni Ribó (ICE)
Place: Alberto Lobo Room

Have you ever found a skeleton in your backyard? Have you ever found four of them? In this presentation I will talk about how four tombs helped me to learn a little bit of history, and how it is to have an archeological site at home. Based on a real story.
Start: 12:30h
Speaker: Serni Ribó (ICE)
Place: Alberto Lobo Room


Have you ever found a skeleton in your backyard? Have you ever found four of them? In this presentation I will talk about how four tombs helped me to learn a little bit of history, and how it is to have an archeological site at home. Based on a real story.
08
November 2019

Star formation, polarization, and magnetic fields in the ALMA era


Start: 12:15h
Speaker: Chat Hull (National Astronomical Observatory of Japan)
Place: Sala Alberto Lobo (ICE building, Campus UAB)

New ALMA polarization observations continue to both expand and confound our understanding of the role played by the magnetic field in low-mass star formation.  The sample of very young, Class 0 protostellar sources observed with high resolution and high sensitivity with ALMA is now large enough that…
Start: 12:15h
Speaker: Chat Hull (National Astronomical Observatory of Japan)
Place: Sala Alberto Lobo (ICE building, Campus UAB)

New ALMA polarization observations continue to both expand and confound our understanding of the role played by the magnetic field in low-mass star formation.  The sample of very young, Class 0 protostellar sources observed with high resolution and high sensitivity with ALMA is now large enough that we are beginning to see the same surprising features in multiple sources.  The first of these are magnetic field morphologies that beautifully trace the outflow cavity walls in several objects, suggesting that the outflow has shaped the magnetic field.  The polarization along the cavities is strongly enhanced, and in some cases is co-located with emission from UV-tracing molecules, suggesting that the origin of the enhanced polarization is the strong irradiation of the outflow cavities.  The second, more puzzling set of features are thin structures with well organized magnetic fields that are not associated with outflow cavity walls, and yet have high polarization fractions in spite of being deeply embedded and far from any obvious source of the photons necessary to align the grains.  I will close by discussing recent ALMA observations of polarization toward much more evolved, Class II protoplanetary disks.  In the case of my work on IM Lup (one of these disks): consistent with some (but not all!) polarization observations of other disks, the polarization at Bands 6 and 7 (1.3 mm and 850 microns) appears to be due to scattering by dust grains, thus complicating the search for magnetic fields in these sources.  While on one hand all of these results challenge our understanding of both magnetic grain-alignment and grain growth, they also have the potential to open up new windows into the dust-grain properties and radiation environments in young star-forming sources.
25
October 2019

Recent results from CARMENES


Start: 12:15h
Speaker: Juan Carlos Morales Peralta (Institut de Ciències de l'Espai (CSIC-IEEC))
Place: Sala Alberto Lobo (ICE building, Campus UAB)

The CARMENES spectrograph is surveying around 300 M-dwarf stars to look for exoplanets. About 20 exoplanets have already been announced, and a number of candidates are still under analysis. These discoveries show that there is wider diversity of exoplanets around low-mass stars that initially expected:…
Start: 12:15h
Speaker: Juan Carlos Morales Peralta (Institut de Ciències de l'Espai (CSIC-IEEC))
Place: Sala Alberto Lobo (ICE building, Campus UAB)

The CARMENES spectrograph is surveying around 300 M-dwarf stars to look for exoplanets. About 20 exoplanets have already been announced, and a number of candidates are still under analysis. These discoveries show that there is wider diversity of exoplanets around low-mass stars that initially expected: from rocky Earth-like planets to gas giants like Jupiter. In this talk, I will summarize some of the last CARMENES results, and I will explain in more detail the last discovery we have made of a Jupiter-like planet orbiting a late-type M-dwarf that challenges planet formation models. 
18
October 2019

Tension on the Hubble constant: systematic uncertainties or new physics?


Start: 12:15h
Speaker: Isaac Tutusaus Lleixa
Place: Sala Alberto Lobo

With the recent increase in precision of our cosmological datasets, measurements of ΛCDM model parameter provided by high- and low-redshift observations started to be in tension. One of the most striking tensions that we have nowadays concerns the value of the expansion rate of the Universe today,…
Start: 12:15h
Speaker: Isaac Tutusaus Lleixa
Place: Sala Alberto Lobo


With the recent increase in precision of our cosmological datasets, measurements of ΛCDM model parameter provided by high- and low-redshift observations started to be in tension. One of the most striking tensions that we have nowadays concerns the value of the expansion rate of the Universe today, the Hubble constant, which is close to a 5-sigma tension between the measurements derived from the cosmic microwave background and local measurements. There are essentially two different reasons that could explain this tension. Either there are some unaccounted systematic uncertainties on the measurements, or there are new physics on our cosmological model that can change the value derived from high-redshift observations. In the recent literature there are plenty of articles focusing on one of these two options to solve the Hubble constant tension. In this talk I will first give a brief introduction on some of the methods to estimate the value of the Hubble constant. I will then present the results of a recent paper where we try to solve the tension by combining the addition of new physics and the addition of unaccounted systematic uncertainties on type-Ia supernovae data. And I will finish by presenting the most promising ideas that could finally solve the tension.
 
11
October 2019

Stellar Population of galaxies and their evolution


Start: 12:15h
Speaker: Helena Domínguez Sánchez (ICE)
Place: Alberto Lobo seminar room

In this talk I will present my research trajectory to the ICE. I will review some of the main observed  galaxy properties and relations and how they change across cosmic time. I will summarise some of my contributions to the field, such as the mass function evolution at high-z, star formation rate measurements,…
Start: 12:15h
Speaker: Helena Domínguez Sánchez (ICE)
Place: Alberto Lobo seminar room

In this talk I will present my research trajectory to the ICE. I will review some of the main observed  galaxy properties and relations and how they change across cosmic time. I will summarise some of my contributions to the field, such as the mass function evolution at high-z, star formation rate measurements, or star formation histories and radial gradients of stellar populations in massive quiescent galaxies. Finally, I will show some of the projects I work on related to machine learning, such as morphological classification of SDSS and DES galaxies, generating synthetic DES images with generative adversarial networks or identification of gravitational lensing and tidal streams.
04
October 2019

Rapidly Evolving Episodic Outflow in the Fastest Water Fountain


Start: 12:15h
Speaker: José María Torrelles Arnedo (ICE-CSIC, CSIC)
Place: Alberto Lobo

Water fountains (WF) are evolved stars showing early stages of collimated mass-loss during transition from the asymptotic giant branch, providing valuable insight into the formation of asymmetric planetary nebulae.  We present the results of our Very Long Baseline Interferometry (VLBI) water maser observations,…
Start: 12:15h
Speaker: José María Torrelles Arnedo (ICE-CSIC, CSIC)
Place: Alberto Lobo

Water fountains (WF) are evolved stars showing early stages of collimated mass-loss during transition from the asymptotic giant branch, providing valuable insight into the formation of asymmetric planetary nebulae.  We present the results of our Very Long Baseline Interferometry (VLBI) water maser observations, which determine the spatial and three-dimensional kinematic structure of the masers associated with the fastest  WF IRAS 18113−2503. The water masers trace three pairs of high-velocity (~150-300 km/s) bipolar bow shocks on a scale of ~0.18 arcsec (~2000 au). The expansion velocities of the bow shocks exhibit an exponential decrease as a function of distance from the central star, which can be explained by an episodic, jet-driven outflow decelerating due to drag forces in a circumstellar envelope. We estimate an initial ejection velocity of ~840 km/s, and a period for the ejections  of 10-20 yr, with the youngest being ~12 yr old. We hypothesize that IRAS 18113−2503 hosts a binary central star with a separation of ~10 au. We also explain the water maser monitoring program we are currently doing on this WF for testing some of our observational predictions.
12
July 2019

THE 1908 TUNGUSKA EVENT: 111 YEARS AFTER, IT STILL MAKES YOU THINK


Start: 12:15h
Speaker: Luigi Foschini (INAF - Brera)
Place: Alberto Lobo

On June 30th, 1908, an explosion flattened more than two thousands square kilometres of Siberian taigà. During the following 111 years, several theories were proposed to explain the observed features. Basically, there is a general agreement on the collision of the Earth with a cosmic body, but still…
Start: 12:15h
Speaker: Luigi Foschini (INAF - Brera)
Place: Alberto Lobo

On June 30th, 1908, an explosion flattened more than two thousands square kilometres of Siberian taigà. During the following 111 years, several theories were proposed to explain the observed features. Basically, there is a general agreement on the collision of the Earth with a cosmic body, but still today there are doubts on the exact dynamics of the phenomenon and the nature of the body (comet or asteroid?). Particularly, I will address the atmospheric fragmentation and the possibility of a ground impact.
28
June 2019

X-MRIs and IMRIs - From extremely large to intermediate


Start: 12:15h
Speaker: Pau Amaro Seoane
Place: Sala Alberto Lobo

The gravitational capture of a compact object by a supermassive black hole is the best probe of strong gravity we have thought of. I will present recent results that predict that such gravitational captures can be detected in the future with space-borne detectors right at our Galactic Centre with…
Start: 12:15h
Speaker: Pau Amaro Seoane
Place: Sala Alberto Lobo


The gravitational capture of a compact object by a supermassive black hole is the best probe of strong gravity we have thought of.
I will present recent results that predict that such gravitational captures can be detected in the future with space-borne detectors
right at our Galactic Centre with extreme signal-to-noise ratios and extremely large mass ratios, via the capture of sub-stellar objects.
Also, I will show that it is likely that current ground-based detectors such as LIGO and Virgo already have buried in their data
captures of intermediate-mass ratios.
 
Institute of Space Sciences (IEEC-CSIC)

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An institute of the Consejo Superior de Investigaciones Científicas

An institute of the Consejo Superior de Investigaciones Científicas
Affiliated with the Institut d'Estudis Espacials de Catalunya

Affiliated with the Institut d'Estudis Espacials de Catalunya