Observaciones en la línea de 21 cm del remanente de supernova G 261.9 + 5.5

Con el radiotelescopio de 30 m del I.A.R. se efectuó un relevamiento del hidrógeno neutro asociado con el remanente de supernova G 261.9 + 5.5. Se analizan las estructuras probablemente asociadas con el mismo, a velocidades intermedias y altas.Asociación Argentina de Astronomí

Observaciones en continuo de radio en 1420 MHz en la dirección de H 1538-32

Se realizaron observaciones en continuo de radio en 1420 MHz en la dirección de la fuente de rayos X blandos H 1538-32, posible viejo remanente de supernova. Se discute la existencia de una cáscara que rodea dicha fuente.Asociación Argentina de Astronomí

Observaciones de HI conectadas con un estallido en rayos X detectado en la zona de Lupus

Neutral hydrogen observations has bee made in the directions of an X-ray flare detected in the Lupus region. The flare position lies within the boundaries of a hole in the HI emission. Several physical parameters are derived and probable interpretations are discussed. The conclusion is that the hole is the result of the ionization produced by two early-type stars: HD 135348 and HD 135764. The first one could be the optical counterpart of the flare.Asociación Argentina de Astronomí

Estudio del remanente de supernova G 261.9 + 5.5 (PKS 0902-38º) en la línea de 21 cm

Como parte de un programa general del estudio de remanentes de supernovas, se discuten los resultados preliminares del remanente G261.9+5.5, encontrándose fuertes evidencias de la existencia de una cáscara de HI que rodea a la zona de emisión del continuo en radio.Asociación Argentina de Astronomí

Descubrimiento de CO asociado al remanente de supernova Puppis A

Se han realizado observaciones en la línea de 21 cm del HI y en la línea de 2.6 mm del CO en dirección al remanente de supernova Puppis A, con el fin de investigar ls condiciones físicas del medio en el que está evolucionando el remanente. Las observaciones del HI fueron realizadas con la antena de 50 m del Instituto Argentino de Radioaastronomía, con una resolución angular de 34 minutos de arco. El relevamiento muestra la presencia de una extensa nube de hidrógeno neutro colindante con el flanco Este del remanente Puppis A (Fig. 1). Dicha nube se detecta a la velocidad de (15'4) km/s, correspondiente a una distancia cinemática del orden de 2 kpc, que es la distancia estimada por otros medios para este remanente (Milne 1979). La concentración tiene una masa de hidrógeno del orden de 10⁴ M⊙ y una densidad de aproximadamente 12 átomos/cm³.Asociación Argentina de Astronomí

Enigma of ultraluminous X-ray sources may be resolved by 3D-spectroscopy (MPFS data)

The ultraluminous X-ray sources (ULXs) were isolated in external galaxies for the last 5 years. Their X-ray luminosities exceed 100-10000 times those of brightest Milky Way black hole binaries and they are extremely variable. There are two models for the ULXs, the best black hole candidates. 1. They are supercritical accretion disks around a stellar mass black hole like that in SS433, observed close to the disk axes. 2. They are Intermediate Mass Black Holes (of 100-10000 solar masses). Critical observations which may throw light upon the ULXs nature come from observations of nebulae around the ULXs. We present results of 3D-spectroscopy of nebulae around several ULXs located in galaxies at 3-6 Mpc distances. We found that the nebulae to be powered by their central black holes. The nebulae are shocked and dynamically perturbed probably by jets. The nebulae are compared with SS433 nebula (W50).Comment: Proceedings of the ESO and Euro3D Workshop "Science Perspectives for 3D Spectroscopy", Garching (Germany), October 10-14, 2005. M. Kissler-Patig, M.M. Roth and J.R. Walsh (eds.

Theoretical overview on high-energy emission in microquasars

Microquasar (MQ) jets are sites of particle acceleration and synchrotron emission. Such synchrotron radiation has been detected coming from jet regions of different spatial scales, which for the instruments at work nowadays appear as compact radio cores, slightly resolved radio jets, or (very) extended structures. Because of the presence of relativistic particles and dense photon, magnetic and matter fields, these outflows are also the best candidates to generate the very high-energy (VHE) gamma-rays detected coming from two of these objects, LS 5039 and LS I +61 303, and may be contributing significantly to the X-rays emitted from the MQ core. In addition, beside electromagnetic radiation, jets at different scales are producing some amount of leptonic and hadronic cosmic rays (CR), and evidences of neutrino production in these objects may be eventually found. In this work, we review on the different physical processes that may be at work in or related to MQ jets. The jet regions capable to produce significant amounts of emission at different wavelengths have been reduced to the jet base, the jet at scales of the order of the size of the system orbital semi-major axis, the jet middle scales (the resolved radio jets), and the jet termination point. The surroundings of the jet could be sites of multiwavelegnth emission as well, deserving also an insight. We focus on those scenarios, either hadronic or leptonic, in which it seems more plausible to generate both photons from radio to VHE and high-energy neutrinos. We briefly comment as well on the relevance of MQ as possible contributors to the galactic CR in the GeV-PeV range.Comment: Astrophysics & Space Science, in press (invited talk in the conference: The multimessenger approach to the high-energy gamma-ray sources", Barcelona/Catalonia, in July 4-7); 10 pages, 6 figures, 2 tables (one reference corrected

Radio emission and jets from microquasars

To some extent, all Galactic binary systems hosting a compact object are potential `microquasars', so much as all galactic nuclei may have been quasars, once upon a time. The necessary ingredients for a compact object of stellar mass to qualify as a microquasar seem to be: accretion, rotation and magnetic field. The presence of a black hole may help, but is not strictly required, since neutron star X-ray binaries and dwarf novae can be powerful jet sources as well. The above issues are broadly discussed throughout this Chapter, with a a rather trivial question in mind: why do we care? In other words: are jets a negligible phenomenon in terms of accretion power, or do they contribute significantly to dissipating gravitational potential energy? How do they influence their surroundings? The latter point is especially relevant in a broader context, as there is mounting evidence that outflows powered by super-massive black holes in external galaxies may play a crucial role in regulating the evolution of cosmic structures. Microquasars can also be thought of as a form of quasars for the impatient: what makes them appealing, despite their low number statistics with respect to quasars, are the fast variability time-scales. In the first approximation, the physics of the jet-accretion coupling in the innermost regions should be set by the mass/size of the accretor: stellar mass objects vary on 10^5-10^8 times shorter time-scales, making it possible to study variable accretion modes and related ejection phenomena over average Ph.D. time-scales. [Abridged]Comment: 28 pages, 13 figures, To appear in Belloni, T. (ed.): The Jet Paradigm - From Microquasars to Quasars, Lect. Notes Phys. 794 (2009

Hidrógeno neutro asociado con remanentes de supernovas australes Lupus Loop y SN 1006 A.D.

Evidences of the existence of a near complete circular shell around the SNR Lupus Loop are presented. The expansion velocity, radius, age and initial energy of the explosion are derived. No appreciable effects on the interstellar medium are detected associated with SN 1006 A.D.Asociación Argentina de Astronomí

Supernova Remnants Interacting with Molecular Clouds: X-Ray and Gamma-Ray Signatures

The giant molecular clouds (MCs) found in the Milky Way and similar galaxies play a crucial role in the evolution of these systems. The supernova explosions that mark the death of massive stars in these regions often lead to interactions between the supernova remnants (SNRs) and the clouds. These interactions have a profound effect on our understanding of SNRs. Shocks in SNRs should be capable of accelerating particles to cosmic ray (CR) energies with efficiencies high enough to power Galactic CRs. X-ray and γ-ray studies have established the presence of relativistic electrons and protons in some SNRs and provided strong evidence for diffusive shock acceleration as the primary acceleration mechanism, including strongly amplified magnetic fields, temperature and ionization effects on the shock-heated plasmas, and modifications to the dynamical evolution of some systems. Because protons dominate the overall energetics of the CRs, it is crucial to understand this hadronic component even though electrons are much more efficient radiators and it can be difficult to identify the hadronic component. However, near MCs the densities are sufficiently high to allow the γ-ray emission to be dominated by protons. Thus, these interaction sites provide some of our best opportunities to constrain the overall energetics of these particle accelerators. Here we summarize some key properties of interactions between SNRs and MCs, with an emphasis on recent X-ray and γ-ray studies that are providing important constraints on our understanding of cosmic rays in our Galaxy