Jean-Pierre Swings

OMC: An Optical Monitoring Camera for INTEGRAL Instrument description and performance

The Optical Monitoring Camera (OMC) will observe the optical emission from the prime targets of the gamma- ray instruments onboard the ESA mission INTEGRAL, with the support of the JEM-X monitor in the X-ray domain. This capability will provide invaluable diagnostic information on the nature and the physics of the sources over a broad wavelength range. Its main scientific objectives are: (1) to monitor the optical emission from the sources observed by the gamma- and X-ray instruments, measuring the time and intensity structure of the optical emission for comparison with variability at high energies, and (2) to provide the brightness and position of the optical counterpart of any gamma- or X-ray transient taking place within its field of view. The OMC is based on a refractive optics with an aperture of 50 mm focused onto a large format CCD (1024 2048 pixels) working in frame transfer mode (1024 1024 pixels imaging area). With a field of view of 5 5 it will be able to monitor sources down to magnitude V = 18. Typical observations will perform a sequence of dierent integration times, allowing for photometric uncertainties below 0.1 mag for objects with V 16.

Hard X-ray emission clumps in the gamma-Cygni supernova remnant: An INTEGRAL-ISGRI view

Spatially resolved images of the galactic supernova remnant G78.2+2.1 (γ-Cygni) in hard X-ray energy bands from 25 keV to 120 keV are obtained with the IBIS-ISGRI imager aboard the International Gamma-Ray Astrophysics Laboratory INTEGRAL. The images are dominated by localized clumps of about ten arcmin in size. The flux of the most prominent North- Western (NW) clump is (1.7 ± 0.4) × 10 −11 erg cm −2 s −1 in the 25-40 keV band. The observed X-ray fluxes are in agreement with extrapolations of soft X-ray imaging observations of γ-Cyg by ASCA GIS and spatially unresolved RXTE PCA data. The positions of the hard X-ray clumps correlate with bright patches of optical line emission, possibly indicating the presence of radiative shock waves in a shocked cloud. The observed spatial structure and spectra are consistent with model predictions of hard X-ray emission from nonthermal electrons accelerated by a radiative shock in a supernova interacting with an interstellar cloud, but the powerful stellar wind of the O9V star HD 193322 is a plausible candidate for the NW source as well.

On the Multiplicity of the O-Star Cyg OB2 #8A and its Contribution to the γ-Ray Source 3EG J2033+4118

We present the results of an intensive spectroscopic campaign in the optical waveband revealing that Cyg OB2 #8A is an O6+O5.5 binary system with a period of about 21.9 days. Cyg OB2 #8A is a bright X-ray source, as well as a non-thermal radio emitter. We discuss the binarity of this star in the framework of a campaign devoted to the study of non-thermal emitters, from the radio waveband to γ-rays. In this context, we attribute the non-thermal radio emission from this star to a population of relativistic electrons, accelerated by the shock of the wind-wind collision. These relativistic electrons could also be responsible for a putative γ-ray emission through inverse Compton scattering of photospheric UV photons, thus contributing to the yet unidentified EGRET source 3EG J2033+4118.

INTEGRAL detection of hard X-rays from NGC 6334: nonthermal emission from colliding winds or an AGN?

Aims. We report the detection of hard X-ray emission from the field o f the star-forming region NGC 6334with the the International Gamma-Ray Astrophysics Laboratory INTEGRAL. Methods. The JEM-X monitor and ISGRI imager aboard INTEGRAL and Chandra ACISimager were used to construct 3-80 keV images and spectra of NGC 6334. Results. The 3-10 keV and 10-35 keV images made with JEM-X show a complex structure of extended emission from NGC 6334 . The ISGRI source detected in the energy ranges 20-40 keV, 40-80 keV, and 20-60 keV coincides with the NGC 6334ridge. The 20-60 keV flux from the source is (1.8±0.37)×10 −11 erg cm −2 s −1 . Spectral analysis of the source revealed a hard power-law component with a photon index about 1. The observed X-ray fluxes are in agreement with extrapolatio ns of X-ray imaging observations of NGC 6334by Chandra ACISand ASCA GIS. Conclusions. The X-ray data are consistent with two very different physical models. A probable scenario is emission from a heavily absorbed, compact and hard Chandra source that is associated with the AGN candidate radio source NGC 6334B. Another possible model is the extended Chandra source of nonthermal emission from NGC 6334 that can also account for the hard X-ray emission observed by INTEGRAL. The origin of the emission in this scenario is due to electron accelerat ion in energetic outflows from massive early type stars. The p ossibility of emission from a young supernova remnant, as suggested by earlier infrared observations of NGC 6334 , is constrained by the non-detection of 44 Ti lines.

The International Liquid Mirror Telescope (ILMT) as a Variability Time Machine

During the year 2012 the International Liquid Mirror Telescope (a collaboration between astronomical institutions in Belgium, Canada, India and Poland) wil see first light. The instrument will provide substantial, in-depth sky coverage and make an unprecedented number of nightly observations.

“Earth-Moon Relationships”: Highlights of the Conference and Concluding Remarks

In the present written version, I have aimed at remaining as close as possible to the presentation I delivered at the Accademia Galileiana, in Padova, on 10 November 2000.

OMC: An Optical Monitoring Camera for INTEGRAL

The INTEGRAL payload has been designed to study simultaneously gamma-ray sources in a wide field of view over many decades in energy (around 2 eV + 4 keV − 20 MeV) and thus make a major contribution to short time-scale high-energy astrophysics. The OMC will observe the optical emission from the prime targets of the gamma-ray instruments with the support of the x-ray monitor. This capability will provide invaluable diagnostic information on the nature and the physics of the sources over a broad wavelength range. The main scientific objectives will be: (1) to monitor the optical emission from the sources observed by the gamma- and x-ray instruments, measuring the time and intensity structure of the optical emission for comparison with variability at high energies, and (2) to provide the brightness and position of the optical counterpart of any gamma- or x-ray transient taking place within its field of view. The OMC will be based on a refractive optics with an aperture of 50 mm focused onto a large format CCD (1024 × 2048 pixels) working in frame transfer mode (1024 × 1024 pixels imaging area). With a field of view of 5° × 5° it will be able to monitor sources down to V = 19 mag. Typical exposures will consist of 10 integrations of 100 seconds each.

Examples of Possible Astronomical Research from the Moon

As stressed at the second International Lunar Exploration Working Group meeting (Kyoto, October 1996), the Moon, if kept free from pollution, contains a series of remarkable astronomical sites. In particular the following fields of instrumentation and research emerge: (1) very low frequency radio-astronomical arrays to be located on the lunar far side for surveying an entirely new spectrum, albeit at fairly low angular resolution; (2) interferometers in several wavebands to search for extrasolar planets as well as to perform other observations (morphological studies e.g.); (3) transit optical telescopes for the detailed observation of dark matter and other targets; (4) millimeter-wave telescopes for high sensitivity cosmic background mapping; (5) infrared telescopes in permanently cryogenic environment (e.g. the lunar South pole); (6) gravitational wave detectors; (7) cosmic-ray and high energy detectors;

The Complex Structure of the Ca II H and K Lines in the Spectrum of the A0ep Star with Infrared Excess HD 190073

Radial velocities and profiles of the components of the H and K lines in the spectrum of HD 190073 are analyzed in a 24-spectrum sample covering the period 1943–74. A 2-to-1 ratio in the radial velocities of some components is shown not to be significant on a spectrum-to-spectrum basis, contrary to suggestions by Merrill (1951) and Scargle (1973). The details of the H and K complex structure are correlated with the profiles of the Balmer lines. Radiative forces acting selectively via a resonance scattering mechanism of Ca+ atoms are capable of producing the main features of the complex profiles of H and K in HD 190073 and in other stars exhibiting similarities to HD 190073 (such as P Cygni Balmer lines and infrared excess).