Past Pizza Lunches

Número de entradas: 152

30
Noviembre 2018

First measurements of heavy precipitation in the ROHP-PAZ mission


Inicio: 12:15h
Ponente: Sergio Tomás Martínez (ICE, CSIC & IEEC)
Lugar: ICE, Bellaterra

The ROHP-PAZ mission has been successfully launched on this February 2018. It carries a payload to detect GNSS radio occultations which for the first time measures polarimetric signals. This allows the detection and a possible quantification of heavy precipitation events together with the thermodynamic…
Inicio: 12:15h
Ponente: Sergio Tomás Martínez (ICE, CSIC & IEEC)
Lugar: ICE, Bellaterra


The ROHP-PAZ mission has been successfully launched on this February 2018. It carries a payload to detect GNSS radio occultations which for the first time measures polarimetric signals. This allows the detection and a possible quantification of heavy precipitation events together with the thermodynamic measurements of a conventional radio occultation. This set of simultaneous observations obtained by a single instrument is regarded as a valuable tool to improve the knowledge about cloud formation and precipitations worldwide. In this dissertation I will explain the first results obtained with this novel technique using the collected data up to October as well as its main challenges and future work for the next years at ICE.
23
Noviembre 2018

Meeting a neighbour: the discovery of Barnard b


Inicio: 12:15h
Ponente: Ignasi Ribas (ICE - IEEC)
Lugar: Alberto Lobo room

Last week we announced the discovery of a candidate super-Earth planet around Barnard’s Star. The planet was found using nearly 800 radial velocities from seven different spectrographs in a large observational effort spanning over 20 years. Because of its proximity, at only 6 light years, Barnard…
Inicio: 12:15h
Ponente: Ignasi Ribas (ICE - IEEC)
Lugar: Alberto Lobo room


Last week we announced the discovery of a candidate super-Earth planet around Barnard’s Star. The planet was found using nearly 800 radial velocities from seven different spectrographs in a large observational effort spanning over 20 years. Because of its proximity, at only 6 light years, Barnard b has potential for further characterisation, including direct imaging. In this talk we will present the details of the search and the analysis of the data, and we will put this new planet in a broad context.
(E. Herrero, M. Perger., A Rosich, I. Ribas)
 
16
Noviembre 2018

SEAGLE: Disentangling galaxy formation with strong gravitational lensing


Inicio: 12:15h
Ponente: Sampath Mukherjee
Lugar: Sala Alberto Lobo

The structure and formation of early-type galaxies (ETGs) can be studied in details using the technique of strong gravitational lensing. In particular, analyzing ETGs in hydrodynamical simulations. I will introduce the SEAGLE (i.e. Simulating EAGLE LEnses) pipeline, that approaches the study of galaxy…
Inicio: 12:15h
Ponente: Sampath Mukherjee
Lugar: Sala Alberto Lobo

The structure and formation of early-type galaxies (ETGs) can be studied in details using the technique of strong gravitational lensing. In particular, analyzing ETGs in hydrodynamical simulations. I will introduce the SEAGLE (i.e. Simulating EAGLE LEnses) pipeline, that approaches the study of galaxy formation through strong gravitational lensing, using a suite of high-resolution hydrodynamic simulations, Evolution and Assembly of GaLaxies and their Environments (EAGLE) project, with the aim of inferring their mass density profiles, dark matter (DM) and baryonic content and mass structure on kilo-parsec scales. This involves bridging analytic modeling, hydrodynamic-numerical simulations, and observations in studying the signature of different galaxy formation physics going on. I will present evidence for mass fluctuations in the DM halos of lensing galaxies via power spectrum studies and constrain the contribution of DM and baryons in them. This also includes generating synthetic realistic lenses systems corresponding to ongoing and upcoming surveys e.g. KiDS, DES, JWST, LSST, and Euclid, in order to predict what can be expected from them. I will show that the galaxy evolution models with either too weak or too strong stellar and/or AGN feedback fail to explain the distribution of observed mass-density slopes. On the other hand, models with constant stellar feedback, or weaker AGN feedback produce strong lenses with total mass density slopes close to isothermal. Further, I will disentangle the degeneracies among DM and stellar initial mass function (IMF) with new IMF variation simulations of EAGLE.
09
Noviembre 2018

Voyager probing dark matter


Inicio: 12:15h
Ponente: Mathieu Boudaud (Laboratoire de Physique Théorique et Hautes Energies )
Lugar: Sala Alberto Lobo (ICE building, Campus UAB)

About 40 years after its launch in 1977, the famous Voyager-1 spacecraft has crossed the heliopause in 2012 and is now exploring the local interstellar medium while sending us unprecedented data. This opens up a new avenue to probe local dark matter via cosmic ray electrons and positrons in the sub-GeV…
Inicio: 12:15h
Ponente: Mathieu Boudaud (Laboratoire de Physique Théorique et Hautes Energies )
Lugar: Sala Alberto Lobo (ICE building, Campus UAB)

About 40 years after its launch in 1977, the famous Voyager-1 spacecraft has crossed the heliopause in 2012 and is now exploring the local interstellar medium while sending us unprecedented data. This opens up a new avenue to probe local dark matter via cosmic ray electrons and positrons in the sub-GeV energy range. After describing a novel semi-analytical method (pinching method) which provides us a complete description of the transport of electrons and positrons at low energy, I’ll present predictions for both the secondary astrophysical background and the pair production mechanisms relevant to dark matter particles annihilation or decay down to the MeV mass range. We combined the constraints from the Voyager and AMS-02 data to get novel and robust limits covering a very extended dark matter particle mass range, from MeV to TeV. For velocity dependent annihilation processes (p-wave), we make use of the Eddington method to compute the phase space distribution function of dark matter particles from the most recent constrained mass model of the Galaxy. Primordial black holes are alternative and also well-motivated candidates for dark matter. Black holes with a mass smaller than ~10^17 g are expected to inject electrons and positrons in the Galaxy through Hawking radiation. I’ll show that Voyager is sensitive to signatures from such black holes and I’ll present novel constraints on the contribution of primordial black holes to dark matter in this mass window. Though extracted from a completely different and new probe, these bounds have a strength similar to those obtained with the extragalactic gamma ray background.
26
Octubre 2018

Water in chondritic asteroids: astrobiological implications for the delivery of water to Earth


Inicio: 12:15h
Ponente: Josep M. Trigo-Rodríguez (ICE)
Lugar: Sala Alberto Lobo (ICE building, Campus UAB)

The chondritic meteorites are fragments of undifferentiated asteroids, and their rock-forming minerals carry chemical signatures providing information about the early solar system environment. A hot topic of debate is the delivery of volatiles to terrestrial planets, understanding that the…
Inicio: 12:15h
Ponente: Josep M. Trigo-Rodríguez (ICE)
Lugar: Sala Alberto Lobo (ICE building, Campus UAB)

The chondritic meteorites are fragments of undifferentiated

asteroids, and their rock-forming minerals carry chemical signatures

providing information about the early solar system environment. A hot

topic of debate is the delivery of volatiles to terrestrial planets,

understanding that the rocks forming our planet were formed under far

more reducing conditions than the carbonaceous chondritic bodies. I'll

present evidence for the accretion of ices and hydrated minerals in

carbonaceous asteroids formed in distant regions of the protoplanetary

disk. At about 5 A.U. highly porous carbon and water-rich materials

consolidated, including stellar grains from nearby stars with

particular isotopic signatures. Some well-preserved carbonaceous

chondrites escaped significant thermal and aqueous alteration so they

present unique features that can be interpreted as evidence of wet

accretion, with direct implications for the delivery of water to Earth

and terrestrial planets. Being the Earth formed 4.5 Ga ago from a more

reducing environment, the last stages of heavy bombardment were

protagonized by transitional asteroids that delivered a significant

part of the terrestrial water.
19
Octubre 2018

Primordial black hole formation and abundance: dependence on the shape of the inflationary power spectrum


Inicio: 12:15h
Ponente: Ilia Musco (Institut de Ciències del Cosmos (ICCUB))
Lugar: Alberto Lobo Seminar Room (ICE, UAB Campus)

Primordial black holes can form in the early Universe from the collapse of cosmological perturbations after the cosmological horizon crossing. They are possible candidates for the dark matter as well as for the seeds of supermassive black holes observed today in the centre of galaxies. In calculations…
Inicio: 12:15h
Ponente: Ilia Musco (Institut de Ciències del Cosmos (ICCUB))
Lugar: Alberto Lobo Seminar Room (ICE, UAB Campus)

Primordial black holes can form in the early Universe from the collapse of cosmological perturbations after the cosmological horizon crossing. They are possible candidates for the dark matter as well as for the seeds of supermassive black holes observed today in the centre of galaxies. In calculations of spherically symmetric collapse, using a large curvature perturbation in the super horizon regime, the initial conditions are specified using the gradient expansion approximation in the long wave length limit. The non linear evolution is then simulated using a Lagrangian relativistic hydrodynamical code. If the perturbation is larger than  a threshold depending on the equation of state and on the specific shape of the perturbation, a black hole is formed. In this talk I will discuss the dependence of PBH formation from the initial shape of the curvature profile showing the relation between the threshold amplitude and the steepness of the perturbation which is linked to the amplitude of the pressure gradients that are developing during the collapse. I will show how to derive the initial curvature profile form the shape of the inflationary power spectrum, which affects also the abundance of PBHs. Depending on the model, a proper calculation, using the shape of the power spectrum, shows that the abundance of PBHs is significantly increased by several order of magnitudes compared to previous estimations.
05
Octubre 2018

Bouncing cosmology from warped extra dimensional scenario


Inicio: 12:00h
Ponente: Tanmoy Paul (Indian Association for the Cultivation of Science (IACS))
Lugar: Alberto Lobo

From the perspective of four dimensional effective theory on a two brane warped geometry model,  we examine the possibility of "bouncing phenomena'' on our visible brane. Our results reveal that the presence of warped extra dimension lead to a non-singular bounce on the brane scale factor…
Inicio: 12:00h
Ponente: Tanmoy Paul (Indian Association for the Cultivation of Science (IACS))
Lugar: Alberto Lobo

From the perspective of four dimensional effective theory on a two brane warped geometry model,  we examine the possibility of "bouncing phenomena'' on our visible brane. Our results reveal that the presence of warped extra dimension lead to a non-singular bounce on the brane scale factor and hence can remove the "big-bang singularity''. We also examine the possible parametric regions for which this bouncing is possible.
29
Junio 2018

The Halo-Galaxy connection and how to model it


Inicio: 12:15h
Ponente: Ismael Ferrero (ICE)
Lugar: Alberto Lobo

I will present the results after analysing the ability of the standard cold dark matter model with cosmological constant (ΛCDM) to reproduce observational results of the dynamics of galaxies. Using rotation curves of dwarf galaxies compiled from the literature, it is shown that the galaxy formation…
Inicio: 12:15h
Ponente: Ismael Ferrero (ICE)
Lugar: Alberto Lobo

I will present the results after analysing the ability of the standard cold dark matter model with cosmological constant (ΛCDM) to reproduce observational results of the dynamics of galaxies. Using rotation curves of dwarf galaxies compiled from the literature, it is shown that the galaxy formation efficiency represents a severe challenge at the low stellar mass of dwarf galaxies for this prevailing cosmological model. I will also show what is the process of creating a synthetic catalogs of galaxies through the implementation of the halo occupation distribution (HOD) in cosmological simulations, an efficient way to model the halo-galaxy connection.
22
Junio 2018

Radial velocities of cool stars with rocky planets


Inicio: 12:15h
Ponente: Manuel Perger
Lugar: Sala Alberto Lobo

We are already able to detect potentially habitable, rocky planets with the precision of modern Doppler spectroscopy. At least if they orbit a low-mass star. In this domain however, magnetic phenomena of the host star affect the measurements and are even able to hide and mimic a true planetary signal.…
Inicio: 12:15h
Ponente: Manuel Perger
Lugar: Sala Alberto Lobo

We are already able to detect potentially habitable, rocky planets with the precision of modern Doppler spectroscopy. At least if they orbit a low-mass star. In this domain however, magnetic phenomena of the host star affect the measurements and are even able to hide and mimic a true planetary signal. A challenge in modern radial velocity planet searches is therefore the understanding of the different stellar contributions. In this talk I will explain how we measure and obtain high-precision radial velocities and how we can disentangle the different origins. With this focus, I will discuss the recent findings of exoplanets like GJ 3998b,c, GJ 3942b, and will give previews on my recent research target.
15
Junio 2018

Using the environment to infer supernova progenitor properties


Inicio: 12:15h
Ponente: Lluís Galbany (Pittsburgh Particle Physics, Astrophysics, and Cosmology Center (PITT PACC). Physics and Astronomy Department, University of Pittsburgh)
Lugar: Alberto Lobo Seminar Room (ICE, UAB Campus)

Integral Field Spectroscopy (IFS) applied to supernova (SN) environmental studies have shown the potential of this technique to directly characterize the galactic environmental parameters at SN locations, compare them to those at different locations of the galaxy, and put constraints on progenitor stars…
Inicio: 12:15h
Ponente: Lluís Galbany (Pittsburgh Particle Physics, Astrophysics, and Cosmology Center (PITT PACC). Physics and Astronomy Department, University of Pittsburgh)
Lugar: Alberto Lobo Seminar Room (ICE, UAB Campus)

Integral Field Spectroscopy (IFS) applied to supernova (SN) environmental studies have shown the potential of this technique to directly characterize the galactic environmental parameters at SN locations, compare them to those at different locations of the galaxy, and put constraints on progenitor stars for different SN types. Here, I will summarize current efforts from the PISCO compilation, Hi-KIDS, and the AMUSING survey, that have put together more than 500 SN hosts observed with IFS, and give details about published results from these 3 datasets.
Institute of Space Sciences (IEEC-CSIC)

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08193 Barcelona.
Phone: +34 93 737 9788
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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