TALKS


Carlos Argüelles
TITLE: New evidence of 50 keV fermionic dark matter from Milky Way & Galactic observables
ABSTRACT: A new model for the distribution of dark matter (DM) in galaxies has been recently introduced, the Ruffini-Argüelles-Rueda (RAR) model, based on a self-gravitating system of massive fermions at finite temperatures. The RAR model, for fermion masses above keV, successfully describes the DM halos in galaxies, and predicts the existence of a denser quantum core towards the center of each configuration. We show here, for the first time, that the introduction of a cutoff in the fermion phase-space distribution, necessary to account for the finite Galaxy size, defines a new solution with a compact quantum core which represents an alternative to the central black hole (BH) scenario for SgrA*. In particular, we show that for a fermion mass in the range $48$~keV$/c^2\lesssim m \lesssim 345$~keV$/c^2$, the DM halo distribution fulfills the most recent data of the Milky Way rotation curves, while harbors a dense quantum core of $4\times10^6 M_\odot$ within the S2 star pericenter. The RAR model is in good agreement with different observed Universal correlations involving DM halos and central super massive BHs for a wide range of galaxy types, suggesting a paradigm shift in the understanding of the role and assembly of the dark matter component on galaxy scales.

Ulisses Barres de Almeida
TITLE: Astroparticle Physics in South America: CTA and the synergy with current and future facilties
ABSTRACT: In this talk I will introduce the current scenario for astroparticle physics in South America, a field which is strongly developing in the continent. The talk will concetrate on a detailed presentation of the status of the Cherenkov Telescope Array (CTA) project, which is the main dedicated observatory in the field, to be installed in the Chilean Andes, near Paranal, and with installation of prototypes planned to start in 2017. A number of other astroparticle physics projects are either in activity or planned for the continent in the next decade, and I will discuss some of them and the potential synergies these could have with CTA. A background to the whole presentation is the potential network of faciltiies and collaborations in astroparticle physics which is building up in the continent and which should mature and further develop to respond to the great scientific potential present for the field in this special corner of the world.

Nora Breton
TITLE: Scattering of light by Born-Infeld electromagnetic black holes
ABSTRACT: In a nonlinear theory light trajectories do not coincide with null geodesics, rather light follows null geodesics of an effective metric. In this contribution we describe how scattering of light by a black hole is affected by the nonlinear electromagnetic field as compared with the charged Reissner-Nordstroem black hole.

Elías Castellanos
TITLE: Scalar Field Configurations as Cosmological Condensed Matter Systems
Elías Castellanos - MCTP, Mexico
ABSTRACT: We explore some properties of a scalar field configuration as some kind of cosmological condensed matter system, in order to confront, in principle, relevant predictions of the model with some cosmological data. In particular, we show that a scalar field configuration in a Schwarzschild-de Sitter spacetime can be interpreted as a trapped Bose-Einstein condensate. The geometry of the curved spacetime background provides in a natural way an effective trapping potential for the scalar field configuration, this fact allows us to explore some thermodynamical properties of the system by means of the Thomas-Fermi approximation, commonly used to describe the behavior of Bose-Einstein condensates. The curvature of the spacetime also induces a position dependent self--interaction parameter, that can be interpreted as a gravitational Feshbach resonance effect that could affect the stability of the cloud.

Miguel Chavez
TITLE: Current Status of the Large Millimeter Telescope
Miguel Chavez (INAOE), David Hughes (INAOE) & the LMT Team
ABSTRACT: I will briefly describe the current status of the Large Millimeter Telescope Alfonso Serrano (LMT), the near-term plans for the telescope and the initial suite of instrumentation. The LMT is a bi-national collaboration between Mexico and the USA, led by the Instituto Nacional de Astrofisica, Optica y Electronica (INAOE) and the University of Massachusetts at Amherst, to construct, commission and operate a 50m-diameter millimeter-wave radio telescope. Construction activities are complete at the 4600m LMT site on the summit of Volcan Sierra Negra, an extinct volcano in the Mexican state of Puebla. First light with the LMT (inner 32m-diameter) was successfully conducted in June and July of 2011, as well as three observing runs within the Early Science Phase (ESP, May 2013-June 2015). I will summarize some of the scientific results so far obtained with observations in the ESP and conducted with the Redshift Search Receiver (@3mm, RSR) and the continuum camera AzTEC (@1.1mm). The LMT antenna, outfitted with its initial and future scientific instruments will be a world-leading scientific research facility for millimeter-wave astronomy.

Fernando Comerón
TITLE: Highlights of the program of the European Southern Observatory
ABSTRACT: The European Southern Observatory (ESO), currently one of the world-leading organizations in astronomy, is beginning the construction of the European Extremely Large Telescope (E-ELT), which will become the largest telescope in the world when it enters operations in the mid-2020s. In many ways the current ESO program is paving the way for the E-ELT, both technically and scientifically, and it also offers a combination of facilities that cover a wide range of astronomical goals. Some highlights of current and planned facilities will be presented, with special mention to GRAVITY, a new instrument designed to test the close environment of the black hole at the center of our Galaxy.

Fabio De Colle
TITLE: Gamma-Ray Bursts
Fabio De Colle - ICN-UNAM, Mexico
ABSTRACT: I will discuss our current understanding of the gamma-ray burst (GRB) jet dynamics. Observations show that long GRBs are associated with the collapse of massive stars, which leads to the formation of an ultra-relativistic jet moving with Lorentz factors up to ~ 200-1000, often associated with an energetic supernova. As the jet propagates through the star, its interaction with the stellar material shapes the resulting supernova. Then, as the jet breaks out of the star and freely expands in the environment, dissipation of kinetic energy in internal shocks and/or at the jet photosphere produces the gamma-ray emission (the "prompt emission"). Finally, as the relativistic flow decelerates, it produces a multi-wavelength afterglow which can be observed in radio during several years. These different stages of evolution of the GRB jet will be described in detail in this talk, focusing in particular on how the interaction of the jet with the environment leads to a powerful multi-wavelength emission extending from gamma to radio frequencies.

José Antonio de Diego
TITLE: High-Redshift Universe Through Gravitational Lensing
José Antonio de Diego - IA-UNAM, Mexico
ABSTRACT: The new generation of 8-10 m optical telescopes makes the study of high redshift galaxies available from earth based observatories. These studies are important to understand the dynamical and chemical evolution of the universe that rule the history of galaxies. An important issue is to understand the epoch of reionization, which can be probed through the properties of the Lyman alpha line of the Hydrogen, and the Lyman Alpha Forest in the spectra of quasars. Gravitational lensing by clusters of galaxies is a powerful observational tool to study such high redshift galaxies. Magnified galaxies can be investigated to put constrains on the high redshift low luminosity tail of the galaxy luminosity function. Currently, we are involved in a program of observations with the 10 m Gran Telescopio Canarias (GTC) to observe a small sample of clusters of galaxies and the high redshift objects around them.

Juan Carlos Degollado
TITLE: Dynamics of scalar fields around black holes
Juan Carlos Degollado - FC-UNAM, Mexico
ABSTRACT: Classical scalar fields provide one of the simplest sources of stress-energy in Einstein's equations. Interest in scalar fields has been stimulated in recent years by theoretical developments in particle physics and cosmology. In particular, ultra-light scalar fields have been invoked as possible candidates to play the role of the dark matter component of the universe. Given the fact that most galaxies seem to contain a super-massive black hole at their centres, it is important to study the dynamical properties of the system. In this talk I will revisit some processes involving time-dependent scalar field configurations around black holes and discuss some recent results.

Nissim Fraija
TITLE: Magnetic fields and high-energy neutrinos in Gamma-Ray Bursts
ABSTRACT: Gamma-Ray Bursts (GRBs) are the most luminous explosions in our universe. It remains a big challenge to reveal the central engine and the emission mechanism that is very efficient with highly nonthermal spectra. We will provide an overview of our current understanding of magnetic fields and high-energy neutrinos in GRBs. Magnetic fields could be estimated for the brightest bursts during the afterglow phase --- arising in the external shock --- using the GeV, X-ray and optical data. The field strength is found to vary from one burst to another depending on degree of magnetization. In addition, we explore the conditions so that the recent neutrino detection by the IceCube experiment could be generated in GRBs.

Christine Gruber
TITLE: Inflation as a thermodynamical phase transition from Geometrothermodynamics
Christine Gruber - ICN-UNAM, Mexico City
ABSTRACT: Geometrical methods in the description of thermodynamical phenomena such as geometrothermodynamics (GTD) have been successfully employed to obtain a phenomenological description of different kinds of cosmic fluids. Imposing the definition of an equilibrium thermodynamic manifold in GTD, general solutions for the fundamental potential of a thermodynamic system as a function of its state parameters can be found.
It turns out that from some of the simplest of these solutions, the kinematics of the standard model of cosmology and in particular the late time phase transition to a dark energy dominated universe can be derived.
By generalizing the fundamental relation to that of a van der Waals like gas, an inflationary phase can be incorporated into the model, while preserving the universe's post-inflationary behaviour. The GTD approach provides an alternative description of cosmological dynamics from a purely thermodynamic point of view, without particular assumptions on the microscopic nature of inflaton, matter or dark energy fields, and thus retains a high degree of generality.

David H. Hughes
TITLE: The Event Horizon Telescope: VLBI observations of supermassive black-holes with the Large Millimeter Telescope
Large Millimeter Telescope Project Director and Principal Investigator
ABSTRACT: The existence of a singularity in space-time, the existence of an event horizon, and hence the existence of black-holes are mathematical predictions of General Relativity. A black hole however has never been observed directly. The detection of a shadow produced by the event horizon, and silhouetted by the surrounding luminous material, will therefore confirm the existence of black holes, and provide a fundamental test and confirmation of the predictions of General Relativity in the strong gravity limit. In this presentation I will describe the Event Horizon Telescope, a world-wide network of 9 millimeter-wavelength telescopes (including the Large Millimeter Telescope), that will make the first spatial and time-resolved images of the event horizon of the nearest supermassive black holes using Very Long Baseline Interferometric observations at 1.3mm towards Sgr A*, in the Galactic center, and the active nucleus of powerful radio galaxy M87.

Omar López-Cruz
TITLE: How Big Can Supermassive Black Holes Grow?
ABSTRACT: We have discovered that Holm 15A, the brightest cluster galaxy in Abell 85 (A85-BCG), could host an ultramassive black hole (UMBH) with a mass up to one hundred billion solar masses. This extreme black hole (BH) mass resulted after extrapolating known BH mass scaling laws. In this talk I review some UMBH formation scenarios, and the role of UMBH in galaxy formation and evolution. I will also comment on the possible derivation of observational constraints for initial BH mass at z~20 with Sci-HI. Sci-HI is a 21 cm Cosmology experiment currently unfolding at the Mexican Island of Guadalupe, one the best radio quiet zones of the Planet.

Alfredo Macias
TITLE: On the incompatibility between quantum theory and general relativity
Alfredo Macías - UAM-Iztapalapa, Mexico
ABSTRACT: The aim of this work is to review the concepts of time in quantum field theory and general relativity to show their incompatibility. We prove that the absolute character of Newtonian time is present in quantum mechanics and also partially in quantum field theories which consider the Minkowsk metric as the background spacetime. We discuss the problems which this non-dynamical time causes in general relativity, a theory characterized by a local dynamical spacetime.

Tonatiuh Matos
TITLE: Dark Matter as Scalar Fields
Tonatiuh Matos - CINVESTAV, Mexico
ABSTRACT: The Cold Dark Matter (CDM) model has been very successful at cosmological scales, their predicting mass and angular power spectrums are remarkable. Nevertheless, at galactic scales CDM has some troubles in predicting the dark matter distribution at the centers of dwarf and LSB galaxies and in predicting the features of satellite galaxies. In the last time it has been proposed that the dark matter could be of scalar field nature. The Scalar Field Dark Matter (SFDM) behaves exactly in the same way as CDM at cosmological scales. Nevertheless, at galactic scales SFDM predicts flat central density dark matter profiles and less formation of substructure, as observed. In this talk we review this properties, deduce some of them in a very simple way and show numerical simulations of galaxies, where the gas form spiral arms and bars as the real galaxies. We also show the predicting mass power spectrum at high redshifts where there are strong differences with CDM, that can be observed with the Great Millimeter Telescope in the near future.
We conclude that the SFDM model fits well the present observations at all scales in a simpler way as the CDM paradigm does.

Eckehard W. Mielke
TITLE: Rotating Boson Stars
Eckehard W. Mielke - UAM--Iztapalapa, Mexico
ABSTRACT: Recently, experimental evidence has been accumulated that fundamental scalar fields, like the Higgs boson, exist in Nature. The gravitational collapse of such a boson cloud would lead to a boson star (BS) as a new type of a compact object. Similarly as for white dwarfs and neutron stars (NSs), there exist a limiting mass, the Kaup limit, below which a BS is stable against complete gravitational collapse to a black hole (BH). Depending the self-interaction of the basic scalars, one can distinguish mini-, axi-dilaton, soliton, charged, oscillating and rotating BSs. Their compactness normally prevents a Newtonian approximation, however, modifications of general relativity (GR), as in the case of Jordan-Brans-Dicke theory, would provide them with gravitational memory. Balance between the quantum pressure due to Heisenberg’s uncertainty principle and gravity permits the existence of a completely stable branch of spherically symmetric configurations. Moreover, as a coherent state, like the vortices of Bose-Einstein condensates, it allows for rotating solutions with quantized angular momentum. In this review, we concentrate on the fascinating possibility of weakening the BH uniqueness theorem for rotating configurations and soliton-type collision of excited BSs.

Felix Mirabel
TITLE: Black Holes in cosmology and Galaxy evolution

Dany Page
TITLE: Probing the Neutron Star Crust from its Thermal Relaxation in Transiently Accreting Binaries
IA-UNAM, Mexico
ABSTRACT: The crust of a neutron star is its outer shell, with a thickness of several hundred meters, and comprising densities from 10^8 up to 10^14 g/cm^3. Nuclei are present in the crust an arrange themselves into a lattice, except in the superficial layers of the liquid ocean. In more than half of its extent nuclei are however immersed in a quantum liquid of superfluid neutrons. The theoretical description of the properties of this crust has reach a high level of sophistication but, nevertheless, many uncertainties remain. The inner part of the neutron star, its core that comprise 98% of the star’s mass, is, in contradistinction, formed by an homogeneous quantum liquid of nucleons and possibly exotic particles at its highest densities and its properties are poorly understood. Quasi-persistent sources are a small family, with six objects to date, of low-mass X-ray binaries in which long outbursts of accretion are followed by years of quiescence during which little or no accretion is occurring. Nuclear reactions occurring in the crust under accretion heat it up significantly and bring it out of thermal equilibrium with the core. When accretion stops, the thermal relaxation of the crust can be, had has been, directly observed and provide us with a gold mine of information about its physical properties. I will present a brief review of neutron star crust physics and describe crust relaxation models and what we have learned from them.

Volker Perlick
TITLE: Influence of a plasma on the light deflection by compact objects
Volker Perlick - ZARM, U Bremen, Germany
ABSTRACT: I discuss light bending by compact objects (black holes, wormholes, ultracompact stars, etc.) that are surrounded by a plasma. The plasma is assumed to be pressureless ("cold"), non-magnetised and optically thin. After deriving the general formula for the bending angle in a plasma under the assumption of spherical symmetry and staticity, I discuss in some detail the angular diameter of the shadow of a compact object in a plasma, again under the same symmetry assumptions. The Schwarzschild spacetime and the Ellis wormhole are treated as particular examples. In the last part, I consider a plasma on the Kerr spacetime. The perspectives of actually observing the discussed effects with supermassive black holes will be addressed as well. - The talk is largely based on joint work with Oleg Tsupko and Gennady Bisnovatyi-Kogan (Space Research Institute, Russian Academy of Science, Moscow).

Jeff Peterson
TITLE: Fast Radio Bursts
Jeff Peterson - Carnegie Mellon University, USA
ABSTRACT: I will report on the discovery of a new fast radio burst with a detection of Faraday rotation, wavelength-dependent scattering, and scintillation. The data imply source location in the dense central region of its host galaxy or the presence of magnetized material associated with the source itself. The burst was detected with GBT at 800MHz. If the observed dispersion is dominated by the intergalactic medium, the FRB sources are at cosmological distances at redshifts 0.2 to 1 and have brightness temperatures as high as 10^35 K, twenty orders of magnitude higher than gamma ray bursts. The eleven bursts detected before are consistent with a wide range of source models ranging from comet impacts on neutron stars to magnetar collapse. The new burst, with evidence of local plasma, will have substantial impact on source models. The new HIRAX telescope, along with CHIME and Tainlai will have the potential to detect 10 FRBs per day and will localize the emission to a single galaxy or star, so there will be much more information on these mysterious object in the next few years.

Dennis Philipp
TITLE: On analytic solutions of wave equations in Schwarzschild spacetime
Dennis Philipp - ZARM, University of Bremen, Germany
ABSTRACT: The propagation of scalar, electromagnetic and gravitational waves on fixed Schwarzschild background is described by the general time-dependent Regge-Wheeler equation. We transform this wave equation to usual Schwarzschild, Eddington-Finkelstein and Painleve-Gullstrand coordinates. The resulting radial equations belong to the class of confluent Heun equations, i.e., we can identify one irregular and two regular singularities. Using the generalized Riemann scheme we collect properties of all the singular points and construct analytic (local) solutions in terms of the standard confluent Heun function HeunC, Frobenius- and asymptotic series. In the adapted coordinate systems we obtain a solution that is regular at the black hole horizon, respectively. This solution describes purely ingoing radiation at r = 2M. To construct solutions on the entire open interval between the singularity at the origin and infinity we give an analytic continuation of local solutions around the horizon. Black hole scattering and QNM are considered as possible applications and we use semi-analytically calculated graybody factors together with the Damour-Ruffini method to reconstruct the power spectrum of Hawking radiation emitted by the black hole.

Hernando Quevedo
TITLE: Geometrothermodynamics
Hernando Quevedo - ICN-UNAM, Mexico
ABSTRACT: In this talk, I will present a review of the fundamentals of geometrothermodynamics (GTD), a formalism that aims to describe the physical properties of a thermodynamic system in terms of the geometric properties of the corresponding space of equilibrium states. It unifies in a consistent and Legendre invariant manner the geometric structures of the thermodynamic phase space and of the equilibrium space. This allows us to associate a specific Riemannian metric to any termodynamic system in such a way that the corresponding curvature turns out to be a measure of the thermodynamic interaction, and curvature singularities correspond to phase transitions. Some applications of the GTD formalism are briefly discussed.

Luis Felipe Rodríguez
TITLE: Tidal disruption of stars and clouds by massive black holes
Luis F. Rodríguez, IRyA, UNAM
ABSTRACT: I review the astrophysical evidence of the disruption of stars that make a close approach to massive black holes. These violent events are traced by luminous flares in the X-rays/UV/optical toward the centers of galaxies. These observations allow estimates of the mass accretion rate and geometry of the matter flow towards the black hole. Finally, I will review the recent results of the passage of the G2 object near Sgr A* in early 2014. Originally interpreted as a cloud of gas and dust, the tidal disruption of G2 was expected to lead to a large increase in the rate of mass accretion, resulting in a large burst in the luminosity of Sgr A* across the electromagnetic spectrum. However, this did not happen and we will summarize the extensive literature on this event.

Jorge Rueda
TITLE: Hypercritical accretion onto neutron stars and the induced gravitational collapse paradigm of gamma-ray bursts associated with supernovae
ABSTRACT: I will give a review of the salient properties of the induced gravitational collapse (IGC) scenario for the explanation of the concomitance of energetic long-duration gamma-ray bursts (GRBs) associated with type Ic supernovae (SNe). The IGC paradigm introduces a binary system as the progenitor of GRB-SN systems: a carbon-oxygen (CO) core forming a very compact binary with a neutron star (NS). The explosion of the CO core triggers a massive accretion process onto the NS bringing it to the critical mass value, inducing its gravitational collapse to a black hole (BH) with consequent emission of the GRB. Recent results of the numerical simulations in full general relativity of the entire process from the SN explosion all the way up to the collapse of the NS will be shown, with especial focus on the role of the NS structure and its exterior spacetime properties.
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Remo Ruffini
TITLE: Supernovae, Neutron Stars, Black Holes and Gamma ray Bursts: in celebration of the Golden Jubilee of Relativistic Astrophysics
ABSTRACT: Following the classical works on Neutron Stars, Black Holes and Cosmology, I outline some recent results obtained in the IRAP-PhD program of ICRANet on the "Cosmic Matrix": a new astrophysical phenomenon recorded by the X- and Gamma-Ray satellites and by the largest ground based optical telescopes all over our planet. In 3 minutes it has been recorded the occurrence of a "Supernova", the "Induced-Gravitational-Collapse" on a Neutron Star binary, the formation of a "Black Hole", and the creation of a "Newly Born Neutron Star".

Gus Sinnis
TITLE: An Eye on the High-Energy Universe: The HAWC Gamma-Ray Observatory
ABSTRACT: The study of the very-high-energy universe began with the detection of TeV gamma-rays from the Crab Nebula in 1990. Since that time VHE gamma rays have been observed from supernova remnants, x-ray binary systems, pulsar wind nebulae, active galaxies, starburst galaxies, and many as yet unknown sources. These observations have been used to understand the acceleration processes at work in the cosmos and the environments of these systems. Many of the sources of VHE gamma rays are time variable or transient in nature, demonstrating the need for a large field-of-view instrument with sufficient sensitivity to study transient phenomena.
There are two well-developed experimental techniques used to study the VHE universe: Imaging Atmospheric Cherenkov Telescopes (IACTs) and Extensive Air Shower (EAS) arrays. The former view a small region of the sky with high sensitivity, while the latter view the entire overhead sky with reduced sensitivity. Historically EAS arrays had been composed of a large number of small plastic scintillators dispersed over a large area. These arrays were insensitive to primary gamma rays in the TeV energy range. The development of water Cherenkov technology for EAS arrays has dramatically improved the sensitivity of EAS arrays in the 100 GeV to 10 TeV energy range. The High Altitude Water Cherenkov (HAWC) Observatory is a second generation water Cherenkov detector operating on the slopes of the Sierra Negra volcano in Puebla, Mexico. In this talk I will present the water Cherenkov technique, the HAWC detector, and discuss recent results from HAWC.

Roberto Sussman
TITLE: Credible modelling of realistic large scale cosmic structures with exact solutions of General Relativity
Roberto Sussman - ICN-UNAM, Mexico
ABSTRACT: We show how a class of exact solutions of Einstein's equations (the Szekeres models) can be worked out to describe an arbitrary number of evolving over-densities and density voids whose spatial location at all times can be prescribed from standard early Universe initial conditions. These configurations provide a fully relativistic and non--perturbative (but coarse grained) description of actually observed 100 Mpc sized structures, which are normally examined by Newtonian n-body simulations or perturbative methods. These networks of evolving multi-structure configurations have an enormous potential for application to address open theoretical and observational issues in Cosmology.