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Highlights are presented of studies of the emission mechanisms in the 4 to 8 micron region of the spectrum using a circular variable filter wheel spectrometer with a PbSnTe photovoltaic detector. Investigations covered include the spectroscopy of planets, stellar atmospheres, highly obscured objects in molecular clouds, planetary nebulae, H2 regions, and extragalactic objects.
We present an overview of the science capabilities enabled by a mid-infrared camera/spectrometer on board the NGST. Even without full mid-IR optimization, a mid-infrared (5-30 microns) instrument on the NGST will be orders of magnitude more sensitive than any equivalent ground-based instrument/telescope combination. In the extragalactic arena, the mid-IR region is critical for a complete understanding of the or high-redshift universe, dusty star-formation regions at low and high redshifts, and starburst vs. AGN discrimination. In the local universe, great strides forward can be made using mid-IR imaging, spectroscopy, and coronagraphy of dusty and rocky disks of all ages, from protostellar to remnant debris disks. Near-neighbor detection and characterization can also be greatly advanced by mid-infrared observations.
Researchers observed CO(7-6), CO(3-2), HCN(3-2) and HCO+(3-2) line emission toward the starburst nucleus of M82 and have obtained an upper limit to H13CN(3-2). These are the first observations of the CO(7-6), HCN(3-2) and HCO+(3-2) lines in any extragalactic source. Researchers took the CO(7-6) spectrum in January 1988 at the Infrared Telescope Facility (IRTF) with the Max Planck Institute for Extraterrestrial Physics/Univ. of California, Berkeley 800 GHz Heterodyne Receiver. In March 1989 researchers used the Institute for Radio Astronomy in the Millimeter range (IRAM) 30 m telescope to observe the CO(3-2) line with the new MPE 350 GHz Superconductor Insulator Superconductor (SIS) receiver and the HCN(3-2) and HCO+(3-2) lines with the (IRAM) 230 GHz SIS receiver (beam 12" FWHM, Blundell et al. 1988). The observational parameters are summarized.
Problems encountered in the design of a submillimeter photometer for the infrared telescope facility and some of the solutions already provided are described. Observations of Saturn's rings and the determination of the brightness temperature of Titan, Jupiter, Saturn, Neptune, and Uranus are summarized. Significant findings during solar, galactic, and extragalactic observations include the discovery of low luminosity star formation in the Bok Globule B335 and determination of the far infrared properties of dust in the reflection nebula NGC 7023.
Intensive searches across the electromagnetic spectrum have shown that transient X-ray binary systems exhibit properties similar to the central engines of AGNs. Having proven that accretion disks are present in both types of systems, it is now the task to determine the accretion physics which brings about the observed phenomena. The galactic superluminal transient sources, which are strongly suspected of containing black holes, are particularly attractive for studying state changes, jets, quasi-periodic behavior, and flaring/outburst behavior on timescales a million times shorter than those of their extragalactic counterparts. The galactic sources GRS 1915+105, GRO J1655-40 and more recently-detected transients such as XTE J1748-288 have demonstrated a rich variety of spectral and temporal behaviors. I review some of these observations from the perspective of high energy astronomy with emphasis on recent data from the Compton Observatory and Rossi X-ray Timing Explorer.
Euclid concept: (1) High-precision survey mission to map the geometry of the Dark Universe (2) Optimized for two complementary cosmological probes: (2a) Weak Gravitational Lensing (2b) Baryonic Acoustic Oscillations (2c) Additional probes: clusters, redshift space distortions, ISW (3) Full extragalactic sky survey with 1.2m telescope at L2: (3a) Imaging: (3a-1) High precision imaging at visible wavelengths (3a-2) Photometry/Imaging in the near-infrared (3b) Near Infrared Spectroscopy (4) Synergy with ground based surveys (5) Legacy science for a wide range of in astronomy
The relationship between the radio and optical emissions from the nucleus of the Seyfert galaxy NGC 4151 is investigated by mapping the radio radiation from this source at wavelengths of 20 and 6 cm using the Very Large Array of the National Radio Astronomy Observatory. Results show that the radio emission at wavelengths from 20 to 6 cm extend 10'' (950 pc) along a position angle of 72-84 degrees. This nonthermal emission is found to consist of at least six components and is similar to jets observed in other compact extragalactic radio sources. These radio jets appear to be coincident with the optical line emission region in NGC 4151 and are aligned with the position angle of the linearly polarized optical continuum emission.
This research program addresses astrophysics research with the Infrared Space Observatory's Long Wavelength Spectrometer (ISO-LWS), including efforts to supply ISO-LWS with superior metal mesh filters. This grant has, over the years, enabled Dr. Smith in his role as a Co-Investigator on the satellite, the PI (Principal Investigator) on the Extragalactic Science Team, and a member of the Calibration and performance working groups. The emphasis of the budget in this proposal is in support of Dr. Smith's Infrared Space Observatory research. This program began (under a different grant number) while Dr. Smith was at the Smithsonian's National Air and Space Museum, and was transferred to SAO with a change in number. While Dr. Smith was a visiting Discipline Scientist at NASA HQ the program was in abeyance, but it has resumed in full since his return to SAO. The Infrared Space Observatory mission was launched in November, 1996, and since then has successfully completed its planned lifetime mission. Data are currently being calibrated to the 2% level.
An instrumental technique from radio astronomy known as very long baseline interferometry (VLBI) offers significant promise for the solution of the problem of accurate long-distance, three-dimensional surveying and determination of whole earth geodynamical phenomena. The methods of VLBI make it possible for receiving stations to be independently operated at arbitrary separations using extragalactic radio sources as their frame of time-invariant angular reference. Feasibility demonstrations at S-band (13 cm) wavelengths have been performed, and accuracies of a few centimeters for three-dimensional surveying over a short distance (16 km) have been demonstrated. VLBI operation on longer baselines (8400 km) has been performed between Goldstone, California, and Madrid, Spain, in order to develop the capability for determination of universal time variations, in addition to the measurements of this intercontinental baseline. Systems analysis indicates that necessary calibrations can be developed so as to make possible the implementation of a transportable radio interferometer station concept.
The goal of the conference was to assess the moon as a base for conducting astronomy, solar system observations, and space sciences. The lunar vacuum allows a complete opening of the electromagnetic window and distortion-free measurements at the highest angular resolution, precision, and temporal stability. The moon is perfect for continuous monitoring of the Sun, Solar System targets, and for deep observations of galactic and extragalactic objects. It is an in-situ laboratory for selenophysics, chemistry, and exobiology. The moon contains useful resources and is accessible from Earth for installation, operations maintenance, robotics, and human activities.
A quasi-inertial reference frame is defined based on the radio positions of 212 extragalactic sources distributed over the entire sky.
The Gamma Ray Large Area Space Telescope (GLAST) is a high energy astronomy mission planned for launch in 2005. GLAST features two instruments; the Large Area Telescope (LAT) operating from 20 MeV - 300 GeV and the Gamma-ray Burst Monitor (GBM) operating from 10 keV - 25 MeV. GLAST observations will contribute to our understanding of active galactic nuclei and their jets, gamma-ray bursts, extragalactic and galactic diffuse emissions, dark matter, supernova remnants, pulsars, and the unidentified high energy gamma-ray sources. The LAT sensitivity is 4 x 10(exp -9) photons per square centimeter per second (greater than 100 MeV) for a one year all-sky survey, which is a factor of greater than 20 better than CGRO/EGRET. GLAST spectral observations of gamma-ray bursts cover over 6 orders of magnitude in energy thanks to the context observations of the GBM. The upper end of the LAT energy range merges with the low energy end of ground-based observatories to provide a remarkable new perspective on particle acceleration in the Universe.
As much as one third of the luminosity of the local universe is emitted in the far infrared. In order to understand the history of energy release in the universe, it is crucial to characterize this rest-frame far-infrared contribution from the present back to the era of initial galaxy formation. Over the redshift range from 0 to 10, this energy is received in the 80 micrometers to 1 mm spectral region. In the 1980's the Infrared Astronomy Satellite (IRAS) all-sky survey provided the first comprehensive view of the far infrared emission from the local universe. The diffuse background measurements by Cosmic Background Explorer Satellite (COBE) have provided constraints on the integral contributions from the high redshift universe. In the past five years, submillimeter measurements made using the SCUBA instrument have revealed powerful high redshift sources. To develop a clear history of energy release in the universe, we need numbers and redshifts of representative populations of energetically important objects. The near future will bring the Space Infrared Telescope Facility Multiband Imaging Photometer (SIRTF)(MIPS) survey, which will cover about 100 square degrees at wavelengths out to 160 micrometers, providing a large sample of energetically important galaxies out to z of approx.3. In 2005, the Japanese IRIS survey will provide a 160 micrometers full sky survey, which will provide larger samples of the high z galaxy populations and will find intrinsically rare high luminosity objects. The SPIRE instrument on the FIRST facility will extend these surveys to longer wavelengths, providing a view of the universe at higher redshifts in three spectral bands. A concept for an all-sky submillimeter survey is under development, called the Survey of Infrared Cosmic Evolution (SIRCE). With a 2 m cryogenic telescope, it can map the entire sky to the confusion limit in the 100 to 500 micrometers range in six months. This survey will provide photometric redshifts, number counts, and will find the most luminous objects in the universe. In the next decade, the opening of the submillimeter, combined with the near infrared capability of NGST will provide us with a clear picture of energy release in the early universe.
Future satellites should carry instruments having over an order of magnitude greater sensitivity than those flown thus far as well as improved energy and angular resolution. The information to be obtained from these experiments should greatly enhance knowledge of: the very energetic and nuclear processes associated with compact objects; the structure of our galaxy; the origin and dynamic pressure effects of the cosmic rays; the high energy particles and energetic processes in other galaxies; and the degree of matter-antimatter symmetry of the universe. The relevant aspects of extragalactic gamma ray phenomena are emphasized along with the instruments planned. The high energy gamma ray results of forthcoming programs such as GAMMA-1 and the Gamma Ray Observatory should justify even more sophisticated telescopes. These advanced instruments might be placed on the space station currently being considered by NASA.
The most reliable measurements in the energy range from 0.1 MeV to 100 MeV are presented in graphs. Studies in the region from 1 keV to 100 keV are discussed, giving attention to nonthermal mechanisms, thermal emission from a uniform intergalactic medium, the contribution of discrete extragalactic sources to the isotropic X-ray background, discrete diffuse X-ray sources in galaxy clusters, the contribution of galaxy clusters to the isotropic X-ray background, and fluctuations in the X-ray background. Diffuse X rays below 1 keV are also considered together with diffuse galactic X and gamma rays above 1 keV and the significance of diffuse X and gamma radiation for astronomy.
The Uhuru catalog of X-ray sources is used to analyze the number versus apparent-intensity relation of X-ray objects, by constructing (log N, log S)-plots similar to those used in radio astronomy. The source number distribution is corrected for nonuniform sky coverage of the spacecraft. Two distinct distributions for objects at low (less than 20 deg) and high (more than 20 deg) galactic latitude are discussed. The distribution for low galactic latitude objects (which are mainly galactic) gives further information on their location within the Galaxy and their intrinsic luminosity. The distribution for high-latitude objects is consistent with an extragalactic origin of these sources. Evidence from the longitudinal distribution of these objects is used to further demonstrate their extragalactic nature.
The principle purpose of this symposium is to provide the EGRET (Energetic Gamma-Ray Experiment Telescope) scientists with an opportunity to study and improve their understanding of high energy gamma ray astronomy. The Symposium began with the galactic diffusion radiation both because of its importance in studying galactic cosmic rays, galactic structure, and dynamic balance, and because an understanding of its characteristics is important in the study of galactic sources. The galactic objects to be reviewed included pulsars, bursts, solar flares, and other galactic sources of several types. The symposium papers then proceeded outward from the Milky Way to normal galaxies, active galaxies, and the extragalactic diffuse radiation.
Cosmic gamma rays, the physical processes responsible for their production and the astrophysical sites from which they were seen are reported. The bulk of the observed gamma ray emission is in the photon energy range from about 0.1 MeV to 1 GeV, where observations are carried out above the atmosphere. There are also, however, gamma ray observations at higher energies obtained by detecting the Cerenkov light produced by the high energy photons in the atmosphere. Gamma ray emission was observed from sources as close as the Sun and the Moon and as distant as the quasar 3C273, as well as from various other galactic and extragalactic sites. The radiation processes also range from the well understood, e.g. energetic particle interactions with matter, to the still incompletely researched, such as radiation transfer in optically thick electron positron plasmas in intense neutron star magnetic fields.