M@TE - Monitoring at TeV Energies

Blazars are extremely variable objects emitting radiation across the electromagnetic spectrum and showing variability on time scales from minutes to years. For the understanding of the emission mechanisms, simultaneous multi-wavelength observations are crucial. Various models for flares predict simultaneous flux increases in the X-ray and gamma-ray band or more complex variability patterns, depending on the dominant process responsible for the gamma-ray emission. Monitoring at TeV energies is providing important information to distinguish between different models. To study duty cycle and variability time scales of an object, an unbiased data sample is essential, and good sensitivity and continuous monitoring are needed to resolve smaller time scales. A dedicated long-term monitoring program at TeV energies has been started by the FACT project. Its success clearly illustrated that the usage of silicon based photo sensors (SIPMs) is ideal for long-term monitoring. They provide not only an excellent and stable detector performance, but also allow for observations during bright ambient light minimizing observational gaps and increasing the instrument's duty cycle. The observation time in a single longitude is limited to 6 hours. To study typical variability time scales of few hours to one day, the ultimate goal is 24/7 monitoring with a network of small telescopes around the globe (DWARF project). The installation of an Imaging Air Cherenkov Telescope is planned in San Pedro Martir, Mexico. For the M@TE (Monitoring at TeV energies) telescope, a mount from a previous experiment is being refurbished to be equipped with a camera using the new generation of SiPMs. In the presentation, the status of the M@TE project will be reported outlining the scientific potential, including the possibility to extend monitoring campaigns to 12 hours by coordinated observations together with FACT.Comment: 5 pages, 1 figure. Contribution to the 6th International Symposium on High Energy Gamma-Ray Astronomy (Gamma2016), Heidelberg, Germany. To be published in the AIP Conference Proceeding

Multiwavelength observations of V479 Andromedae: a close compact binary with an identity crisis

We conducted a multi-wavelength study to unveil the properties of the extremely long-period cataclysmic variable V479 And. We performed series of observations, including moderate to high spectral resolution optical spectrophotometry, X-ray observations with Swift, linear polarimetry and near-IR photometry. This binary system is a low-inclination ~ 17^o system with a 0.594093(4) day orbital period. The absorption line complex in the spectra indicate a G8--K0 spectral type for the donor star, which has departed from the zero-age main sequence. This implies a distance to the object of about 4 kpc. The primary is probably a massive 1.1-1.4 Msun magnetic white dwarf, accreting matter at a rate M(dot) > 10^-10 Msun/ yr. This rate can be achieved if the donor star fills its corresponding Roche lobe, but there is little observational evidence for a mass-transfer stream in this system. An alternative explanation is a stellar wind from the donor star, although such a high rate mass loss is not anticipated from a subgiant. If the strongly magnetic white dwarf in V479 And. is confirmed by future observations, the system the polar with the longest observed orbital period. We also discuss the evolutionary state of V479 And.Comment: 12 pages, 12 figures, accepted for publication in Astronomy and Astrophysic

The evolution of the optical spectrum of V455 Andromedae throughout the 2007 superoutburst

V455 And is a dwarf nova with a short orbital period, close to the orbital period minimum. The object underwent its first detected outburst in 2007, brightening from around V = 16.5 all the way to magnitude 8. Outbursts of such amplitude occur exclusively in dwarf novae with short periods (typically P orb ≲ 90 minutes) and are called superoutbursts. The recurrence time of superoutbursts is long (decades), hence only very few have been studied in detail. We succeeded in observing the entire superoutburst of V455 And spectroscopically from the rise to the decline with unprecedented detail. While the light curve of the object throughout the outburst does not seem to differ much from other dwarf novae, its spectroscopic behavior is strikingly different during the transition stage from the absorption-dominated lines to the strong emission one during the rise. We interpret the emergence of the strong emission lines with little radial velocity variations during the superoutburst as evidence of wind from the evaporating disk in this high-inclination system. The evolution of the line profiles from wide to narrow peak separation during the rise, and back at the decline, matches models showing that the peak separation is a function of optical depth in the lines

On the nature of the hard X-ray sources SWIFT J1907.3-2050, IGR J12123-5802 and IGR J19552+0044

The INTEGRAL and Swift hard X-ray surveys have identified a large number of new sources, among which many are proposed as Cataclysmic Variables (CVs). Here, we present the first detailed study of three X-ray-selected CVs, Swift J1907.3-2050, IGR J12123-5802 and IGR J19552+0044 based on XMM-Newton, Suzaku, Swift observations and groundbased optical and archival (near-IR) nIR/IR data. Swift J1907.3-2050 is highly variable from hours to months-years at all wavelengths. No coherent X-ray pulses are detected but rather transient features. The X-ray spectrum reveals a multitemperature optically thin plasma absorbed by complex neutral material and a soft blackbody component arising from a small area. These characteristics are remarkably similar to those observed inmagnetic CVs. A suprasolar abundance of nitrogen could arise from nuclear processed material from the donor star. Swift J1907.3-2050 could be a peculiar magnetic CV with the second longest (20.82 h) binary period. IGR J12123-5802 is variable in the X-rays on a time-scale of ≳ 7.6 h. No coherent pulsations are detected, but its spectral characteristics suggest that it could be a magnetic CV of the Intermediate Polar (IP) type. IGR J19552+0044 shows two X-ray periods, ~1.38 h and ~1.69 h and an X-ray spectrum characterized by a multitemperature plasma with little absorption. We derive a low accretion rate, consistent with a CV below the orbital period gap. Its peculiar nIR/IR spectrum suggests a contribution from cyclotron emission. It could either be a pre-polar or an IP with the lowest degree of asynchronism.Facultad de Ciencias Astronómicas y GeofísicasInstituto de Astrofísica de La Plat

On the nature of the hard X-ray sources SWIFT J1907.3-2050, IGR J12123-5802 and IGR J19552+0044

The INTEGRAL and Swift hard X-ray surveys have identified a large number of new sources, among which many are proposed as Cataclysmic Variables (CVs). Here, we present the first detailed study of three X-ray-selected CVs, Swift J1907.3-2050, IGR J12123-5802 and IGR J19552+0044 based on XMM-Newton, Suzaku, Swift observations and groundbased optical and archival (near-IR) nIR/IR data. Swift J1907.3-2050 is highly variable from hours to months-years at all wavelengths. No coherent X-ray pulses are detected but rather transient features. The X-ray spectrum reveals a multitemperature optically thin plasma absorbed by complex neutral material and a soft blackbody component arising from a small area. These characteristics are remarkably similar to those observed inmagnetic CVs. A suprasolar abundance of nitrogen could arise from nuclear processed material from the donor star. Swift J1907.3-2050 could be a peculiar magnetic CV with the second longest (20.82 h) binary period. IGR J12123-5802 is variable in the X-rays on a time-scale of ≳ 7.6 h. No coherent pulsations are detected, but its spectral characteristics suggest that it could be a magnetic CV of the Intermediate Polar (IP) type. IGR J19552+0044 shows two X-ray periods, ~1.38 h and ~1.69 h and an X-ray spectrum characterized by a multitemperature plasma with little absorption. We derive a low accretion rate, consistent with a CV below the orbital period gap. Its peculiar nIR/IR spectrum suggests a contribution from cyclotron emission. It could either be a pre-polar or an IP with the lowest degree of asynchronism.Facultad de Ciencias Astronómicas y GeofísicasInstituto de Astrofísica de La Plat

Closing gaps to our origins : EUVO: the ultraviolet-visible window into the Universe

This article reproduces the contents of the White Paper entitled by the same name submitted to the call issued by the European Space Agency soliciting ideas from the scientific community for the science themes that should be covered during the Voyage 2050 planning cycle. This contribution focus in the investigation of the emergence of life and the role that astronomy has to play in it. Three fundamental areas of activity are identified: [1] measuring the chemical enrichment of the Universe, [2] investigating planet formation and searching for exoplanets with signatures of life and, [3] determining the abundance of amino acids and the chemical routes to amino acid and protein growth in astronomical bodies. This proposal deals with the first two. The building blocks of life in the Universe began as primordial gas processed in stars and mixed at galactic scales. The mechanisms responsible for this development are not well-understood and have changed over the intervening 13 billion years. To follow the evolution of matter over cosmic time, it is necessary to study the strongest (resonance) transitions of the most abundant species in the Universe. Most of them are in the ultraviolet (UV; 950 Å - 3000 Å ) spectral range that is unobservable from the ground; the “missing” metals problem cannot be addressed without this access. Habitable planets grow in protostellar discs under ultraviolet irradiation, a by-product of the accretion process that drives the physical and chemical evolution of discs and young planetary systems. The electronic transitions of the most abundant molecules are pumped by this UV field that is the main oxidizing agent in the disc chemistry and provides unique diagnostics of the planet-forming environment that cannot be accessed from the ground. Knowledge of the variability of the UV radiation field is required for the astrochemical modelling of protoplanetary discs, to understand the formation of planetary atmospheres and the photochemistry of the precursors of life. Earth’s atmosphere is in constant interaction with the interplanetary medium and the solar UV radiation field. The exosphere of the Earth extends up to 35 planetary radii providing an amazing wealth of information on our planet’s winds and the atmospheric compounds. To access to it in other planetary systems, observation of the UV resonance transitions is required. The investigation for the emergence of life calls for the development of large astronomical facilities, including instrumentation in optical and UV wavelengths. In this contribution, the need to develop a large observatory in the optical and in the UV is revealed, in order to complete the scientific goals to investigate the origin of life, inaccessible through other frequencies in the electromagnetic spectrum