Past Pizza Lunches

Number of entries: 155

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.
 
21
June 2019

Simulating Pixels


Start: 12:15h
Speaker: Santiago Serrano Elorduy
Place: Sala Alberto Lobo

Pixel simulations are essential in serval phases of a project as they provide mock data that allows us to design, test and optimize the analysis of the images, prior to the real observations. They are also key to evaluate the performance of a survey and help understanding the causes of unknown systematics…
Start: 12:15h
Speaker: Santiago Serrano Elorduy
Place: Sala Alberto Lobo

Pixel simulations are essential in serval phases of a project as they provide mock data that allows us to design, test and optimize the analysis of the images, prior to the real observations. They are also key to evaluate the performance of a survey and help understanding the causes of unknown systematics once the mission starts.

In this talk I will explain the work I (with many others) have done in producing pixel image simulations for various cosmology surveys such as DES, DESI, PAU and Euclid. For the Dark Energy Survey Camera (DECam) and the Dark Energy Spectroscopy Instrument (DESI) were we are responsible of the auto-guiding system we simulated realistic detector images. Secondly, I will present the PAUCam-WHT pixel simulations, used to design the data reduction pipeline. And finally I will give an overview of the Euclid science ground segment and explain the work at the Organization Unit of SIM, detailing all the end-to-end simulations we are currently delivering for the mission.
 
14
June 2019

The star formation history in the solar neighborhood as told by massive white dwarfs


Start: 12:15h
Speaker: Jordi Isern Vilaboy
Place: Sala Alberto Lobo

White dwarfs are the remnants of low and intermediate mass stars. Because of electron degeneracy, their evolution is just a simple gravothermal process of cooling. Recently, thanks to Gaia data, it has been possible to construct the luminosity function of massive (0.9 < M/Msun < 1.1) white dwarfs in…
Start: 12:15h
Speaker: Jordi Isern Vilaboy
Place: Sala Alberto Lobo

White dwarfs are the remnants of low and intermediate mass stars. Because of electron degeneracy, their evolution is just a simple gravothermal process of cooling. Recently, thanks to Gaia data, it has been possible to construct the luminosity function of massive (0.9 < M/Msun < 1.1) white dwarfs in the solar neighborhood (d < 100 pc). Since the lifetime of their progenitors is very short, the birth times of both, parents and daughters, are very close and allow to reconstruct the (effective) star formation rate. This rate started growing from zero during the early Galaxy and reached a maximum 6-7 Gyr ago. It declined and ~5 Gyr ago started to climb once more reaching a maximum 2 - 3 Gyr in the past and decreased since then. There are some traces of a recent star formation burst, but the method used here is not appropriate for recently born white dwarfs.
07
June 2019

Simulations on reverberating and superefficient pulsar wind nebulae


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

Pulsar wind nebulae (PWNe) experience significant evolution in reverberation phase, when the reverse shock created by the supernova explosion travels back towards the pulsar, compressing the wind bubble. We numerically studied the radiative properties of the reverberation phase of several well-characterized…
Start: 12:15h
Speaker: Tingting Lin (Institut de Ciències de l'Espai (CSIC-IEEC))
Place: Sala Alberto Lobo (ICE building, Campus UAB)

Pulsar wind nebulae (PWNe) experience significant evolution in reverberation phase, when the reverse shock created by the supernova explosion travels back towards the pulsar, compressing the wind bubble. We numerically studied the radiative properties of the reverberation phase of several well-characterized PWNe and discovered that even the Crab nebula, associated to the more energetic pulsar of the sample we consider, has a period in its future time evolution where the X-ray luminosity will exceed the spin-down power at the time. In fact, all nebulae in our sample are expected to have a period of radio, X-ray, and GeV superefficiency, and most will also have a period of TeV superefficiency. We then explored a broad range of PWN models to study their reverberation and superefficiency phases in a systematic way in order to analyze how many Galactic PWNe are expected to be reverberating, or in a superefficiency at any given time. We also provide predictions for the future evolution of the magnetar nebula J1834.9-0846 along the next 50 years. I will talk about the characterization of the superefficiency period we discovered in our numerical study.
31
May 2019

Public communication of science. A portal to the public: IATE &OAC experience


Start: 12:15h
Speaker: Victoria Rubinstein (Observatorio Astronomico de Cordoba, Argentina)
Place: Sala Alberto Lobo (ICE building, Campus UAB)

Science communication is a growing area of practice and research. During the past two decades, the number of activities, courses, and practitioners has steadily increased. But why is important to do Science Communication? In the 21st century, a general knowledge and understanding of scientific concepts…
Start: 12:15h
Speaker: Victoria Rubinstein (Observatorio Astronomico de Cordoba, Argentina)
Place: Sala Alberto Lobo (ICE building, Campus UAB)


Science communication is a growing area of practice and research. During the past two decades, the number of activities, courses, and practitioners has steadily increased. But why is important to do Science Communication?
In the 21st century, a general knowledge and understanding of scientific concepts is required for making the best choices for our families, our society, our planet, and ourselves. Unfortunately, formal education often falls short on providing the necessary science-related skills, literacy, and proficiency for optimally navigating life. As such, informal science learning, often through effective science communication by research-active scientists, can play a vital role for a functioning society.
In my talk, I will show what are the activities that we carry out from the IATE and the OAC, in terms of public communication of science, outreach  and teaching. I will show the results of the practice of these activities, in social networks, media etc, and I will end with the idea of encouraging scientists to communicate their own research to the public.
24
May 2019

The heart of darkness


Start: 12:15h
Speaker: Diego Torres (ICE)
Place: Alberto Lobo room

Can a molecular cloud beat?
Start: 12:15h
Speaker: Diego Torres (ICE)
Place: Alberto Lobo room

Can a molecular cloud beat?
17
May 2019

Particle acceleration in protostellar jets: an observational approach


Start: 12:15h
Speaker: Adriana R. Rodriguez Kamenetzky (Instituto de Astronomía Teórica y Experimental, Córdoba, Argentina)
Place: Sala Alberto Lobo (ICE building, Campus UAB)

Deeply embedded protostellar jets are well known to be dominated by the emission of thermal electrons. Interestingly, in the last decades, negative spectral indices have been detected at centimeter wavelengths in some protostellar jets, indicating the presence of a non-thermal component. Detecting non-thermal…
Start: 12:15h
Speaker: Adriana R. Rodriguez Kamenetzky (Instituto de Astronomía Teórica y Experimental, Córdoba, Argentina)
Place: Sala Alberto Lobo (ICE building, Campus UAB)

Deeply embedded protostellar jets are well known to be dominated by the emission of thermal electrons. Interestingly, in the last decades, negative spectral indices have been detected at centimeter wavelengths in some protostellar jets, indicating the presence of a non-thermal component. Detecting non-thermal emission implies the existence of relativistic particles interacting with magnetic fields, and therefore, the action of a mechanism able to efficiently accelerate them. In this talk I will discuss the conditions that need to be met in order to produce efficient particle acceleration in these low energy systems, based on the analysis of radio continuum images of two representative young stellar objects, obtained with the Karl G. Jansky Very Large Array.
10
May 2019

General relativity and extreme-mass-ratio binaries


Start: 12:15h
Speaker: ((ICE, CSIC/IEEC))
Place: Alberto Lobo Room

In this talk, I will give a broad and largely non-technical overview of general relativity and strong gravitational two-body systems, from the status of their theoretical modeling to their observation via gravitational waves. I will focus on the problem of modeling binaries with extreme mass ratios,…
Start: 12:15h
Speaker: ((ICE, CSIC/IEEC))
Place: Alberto Lobo Room

In this talk, I will give a broad and largely non-technical overview of
general relativity and strong gravitational two-body systems, from the
status of their theoretical modeling to their observation via
gravitational waves. I will focus on the problem of modeling binaries with
extreme mass ratios, an ongoing effort among theorists today with which
our group is actively involved, and which is needed for their future
observation, promising unique astrophysical information, with planned
space-based gravitational wave detectors such as LISA.
Institute of Space Sciences (IEEC-CSIC)

Campus UAB, Carrer de Can Magrans, s/n
08193 Barcelona.
Phone: +34 93 737 9788
Email: ice@ice.csic.es
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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