Scintillation Counters for XRay Astronomy

In 1964, the first observation of hard X-rays from the Crab was performed by Clark 2 with a NaI(Tl) scintillation counter on a balloon payload. Subsequent balloon and satellite payloads used the well-type configuration. In balloon instruments, large (100 cm2) crystals were coupled to standard 5 in. phototubes. In the mid 1970s, the first phoswich detectors were built, first by the UCSD and MIT groups 8 followed soon by the MPE AIT collaboration 9 . Because of this improved shielding technique,...

The First 30 Years 2411 Discovery and BATSE

Gamma-ray bursts (GRBs) are short bursts of high-energy radiation from an unpredictable location in the sky. The y-ray emission can rise to maximum intensity within fractions of a millisecond. During these short times GRBs are the brightest objects in the y-ray sky. The energy spectra are nonthermal, with most of the power radiated in the 100-500 keV range, but photons up to 18GeV or down to a few kiloelectronvolt have also been registered. The bursts have durations of typically 0.1-100 s, with...

Solar Wind 931 Comets

The Sun is emitting a wind that contains mainly H and He ions and electrons, plus a minor fraction ( 0.1 ) of heavier, highly charged elements. This wind is ejected at some hundred kilometers per second and expands so quickly that the ions and electrons usually have no chance to recombine. The ions remain in their highly charged state until they encounter the gas in a cometary coma, where electrons are available in large numbers. When the ions capture such electrons, they attain highly excited...

I I I

Fig. 14.7 Observations of surface temperatures and upper bounds for several isolated neutron stars. The solid line is the basic theoretical cooling curve of a nonsuperfluid neutron star with M 1.3 M 112 . The upper limit on the temperature of the old pulsar PSR 1929+10 was added 8 B1055-52 78,79 , and a few other sources. ROSAT also discovered seven neutron stars showing pure thermal emission in X-rays (see next paragraph). More sources and many more details on spectra and time variability were...

Introduction

The history of X-ray astronomy is closely related to solar system research the first attempts ever to detect X-rays from a celestial object concentrated onto the Sun 21 , and the (unsuccessful) attempt to detect X-rays from the Moon, in 1962, is generally considered as the birth of X-ray astronomy 22 . In the recent decade, our knowledge about the X-ray properties of solar system objects was considerably enhanced. We know today that not only the Sun and Moon radiate in X-rays, but that our...

Einstein OGS

The objective transmission grating (OGS) onboard the Einstein Observatory, launched in 1978, consisted of two transmission gratings (500 and 100 lmm-1), either of which could be placed in the X-ray optical path at the exit from the mirror 8 . The mirror had a focal length of 3.4m. The gratings consisted of gold bars nominally 0.2 m thick and with a bar width equal to half of the grating period. The OGS was supplied by SRON in Utrecht Netherlands. The high resolution imager (HRI) was used to...

Sn1978k

SN 1978K is one of the most remarkable X-ray supernovae. It is located in the nearby late-type SB spiral galaxy NGC 1313 (at a distance of 4.1 Mpc). A 1980, Einstein IPC image showed two bright sources in NGC 1313 with LX > 1039 ergs-1, one near the nucleus and one 6arcmin to the south. A 1992 ROSAT PSPC image revealed a third source to the east-southeast of the nucleus, nearly as bright as the other two, and nearly forming an equilateral triangle with them. An optical counterpart had been...

References

Bhardwaj, A., Branduardi-Raymont, G., Eisner, R.F., et al. 2005, Geophys. Res. Lett., 32, L03S08 2. Bhardwaj, A., Eisner, R. F., Waite Jr., et al. 2005, Astrophys. J., 624, L121 3. Bhardwaj, A., Eisner, R. F., Waite Jr., et al. 2005, Astrophys. J., 627, L73 4. Bhardwaj, A., Eisner, R. F., Gladstone, G. R., et al. 2006, J. Geophys. Res., 111, A11, 225 5. Bhardwaj, A., Gladstone, G.R., Elsner, R.F., et al. 2007, J. Atm. Solar Terr. Phys., 69, 179 6. Bodewits, D., Christian, D.J., Torney, M., et...

Gas Scintillation Proportional Counters

Gas scintillation proportional counters (GSPC), developed in 1972 20 , offer the advantage of an enhanced energy resolution when compared with proportional counters. In conventional proportional counters, the charge generated by an ionizing event is multiplied in a high electrical field. The amplification grows exponentially with the number of ionizing collisions of an electron in the high field region. Only 14 ionizing collisions result in a charge multiplication of four orders of magnitude....

Equipartition of Ions and Electrons

While time dependent ionization has become a commonplace assumption in the fitting of the thermal spectra from SNRs, most results tacitly assume equipartition between the ion and electron temperatures.1 Ions are instantaneously heated to a high kinetic temperature as a result of passage through the shock. Models of initial electron heating cover the full range between no heating (Te Ti me mi) and instantaneous equipartition (Te Ti). The primary process by which electrons are thought to...

Connection ofXRay Emission with Other Stellar Parameters

Given the observed spread of X-ray luminosity for stars of given spectral type, anat-ural question to ask is which other stellar parameters except those determining the position of a star in the HR diagram determine the X-ray output level. For late-type main-sequence stars the X-ray emission scales with rotation velocity 34 . This relation is believed to trace directly back to the stellar dynamo. On theoretical grounds, the most adequate measure for the dynamo efficiency should be the Rossby...

Low Mass Xray Binaries LMXB

The optical companions of LMXB are generally of spectral type A to M with less than two solar masses. The mass transfer through Roche lobe overflow feeds an optically thick accretion disk, the X-ray emission of which often dominates the optical and UV appearance of the binary. The Lx Lopt is typically 100-1000, except in those systems where an accretion disk corona (ADC) hides the central source leading to a much reduced Lx Lopt of < 20. Heating of the optical star by the compact X-ray source...

High Energy Emission Properties of Neutron Stars

As a result of observations with the satellite observatories Einstein, ROSAT, ASCA, BeppoSAX, Chandra, and XMM-Newton, 80 rotation-powered pulsars were detected at X-ray energies until the end of 2006. Thus, in 7 yrs of operation XMM-Newton and Chandra have more than doubled the number of detected X-ray pulsars compared to what was known at the end of the ROSAT mission in December 1999 11 . Table 14.2 reflects the progress made in detecting pulsars of various categories at X-ray energies in...

Early XRay Observations

Early X-ray observation in this region with rocket and satellite instrumentation have revealed many variable, but few steady, sources. Uhuru observations showed the first evidence for an extended source, although not distinguishable from a source complex. Subsequent observations with other satellite instruments have led to the detection of several new sources, including bursters. But not earlier than with the Einstein Observatory in 1979, X-ray imaging of the Galactic Center could be performed...

Sn1970g

A deep Chandra image of M101 allowed the detection of SN 1970G 35yrs after its explosion, making it the oldest supernova detected in X-rays 73 . The deep observation allowed detection of the object with a relatively low luminosity, LX (1.1 0.2) x 1037 erg s-1. This luminosity is consistent with a mass loss rate of (2.6 0.4) x 10-5(vw 10kms-1)M yrs-1. Its long term X-ray light curve, reconstructed from archival observations, is steep compared with those of most X-ray SNe, with a profile Lx <...

Principle

Optical elements for X-rays are based on the principle of grazing incidence reflection. Reflection, absorption, and transmission are expressed through the complex index of refraction, which can be written as where 8 describes the phase change and P accounts for the absorption. The optical constants 8 and P are functions of the wavelength or the photon energy (Fig. 6.1). For X-rays, the real part of n, 1 - 8, is slightly less than unity for matter whereas it is exactly unity in vacuum. X-rays...

Relativistic Iron Line

As shown in the preceding section, there is accumulating evidence for the absence of a material surface in the secure and candidate black-hole XBs. A further crucial step is to find strong relativistic effects the unique features expected in the direct vicinity of the event horizon of black holes. In some Seyfert galaxies, the iron K-lines are found to be relativistically broadened highly asymmetric, extended to low energies (e.g., 19, 52, 77 ). This feature strongly suggests that the line is...

Cluster Masses and Composition 2321 Mass Determination

The precise knowledge of the masses of the most massive, gravitationally confined objects is not only interesting as such, but it is also a prerequisite to many of the astrophysical and cosmological studies with clusters. The X-ray method of mass determination is based on the assumption that the ICM constitutes an atmosphere, which is approximately in hydrostatic equilibrium in the cluster potential described by the equation p VP -G1ML(r). In most cases a spherically symmetric approximation is...

Temporal Aperture Modulation

Through movement of the aperture a temporal modulation of the signal from the X-ray source of interest is introduced. For this method, a spatial resolution of the detector surface is not required. A historically interesting way to modulate the aperture is to make use of the occultation of an X-ray source by another celestial body, e.g., the moon. As seen from the earth (or from a satellite), the moon scans certain parts of the sky and occults sources that happen to lie in the half degree wide...

Extragalactic SNRs

X-ray studies of extragalactic SNRs were first facilitated by the imaging capabilities of the Einstein Observatory. While Einstein detected (and discovered) remnants in the Magellanic Clouds, it did not have sufficient sensitivity to detect a substantial number of SNRs in more distant galaxies. ROSAT and ASCA made major contributions to the study of Magellanic Cloud remnants. Additionally, ROSAT also carried out detailed studies of the source populations of nearby galaxies and in so doing was...

Close Binary Supersoft XRay Sources CBSS

One of the important imprints left behind by ROSAT is the observational definition of a class of supersoft X-ray sources with blackbody temperatures kT lt 100 eV 21,24,87 . A prime property of most SSS seems to be a short duty cycle of X-ray bright states as evidenced by the fact that observations of M31 with Chandra and XMM-Newton failed to find most SSS discovered previously with ROSAT 24 . On the other hand, some CBSS, as CAL83 and CAL87 in the Large Magellanic Cloud were discovered already...

ROSAT All Sky Survey Which Stars are XRay Emitters

Within the framework of the ROSAT All-Sky Survey RASS , it was possible to carry out a sensitive and unbiased survey of X-ray emission from all types of stars. Flare on EQ Peg, 1994.06.23 12 ii i i i i i i i i i i i i i i i i i i i i i i . . MEKASPEK B-band 80 11 1 1 30 Li_ '-i i I_i_i_i_i_LlL_ ill _i_i_i I i_i_i_i_J_i_i_i_i_ Fig. 10.4 Simultaneous optical and ROSAT X-ray observation of the flare star EQ Peg during a flare Quite a number of stellar surveys had previously been carried out with...

List of Contributors

Max-Planck-Institut f r extraterrestrische Physik, Giessenbachstra e, 85748 Garching, Germany e-mail web mpe.mpg.de Institut f r Astrophysik, Friedrich-Hund-Platz 1, 37077 G ttingen, Germany, e-mail beuermann astro.physik. uni-goettingen.de Max-Planck-Institut fur extraterrestrische Physik, Giessenbachstra e, 85748 Garching, Germany e-mail hxb mpe.mpg.de Max-Planck-Institut fur extraterrestrische Physik, Giessenbachstra e, 85748 Garching, Germany e-mail bol mpe.mpg.de Universitat Wien,...

Geocorona Mars Exosphere and Heliosphere

While comets provide the cleanest case for studying charge exchange interactions, this is a general process that occurs whenever highly charged ions interact with gas. One such place is the geocorona, an extended, tenuous cloud of hydrogen around the Earth, which is well visible in the EUV because of fluorescent La scattering of solar EUV radiation Fig. 9.3, right . Although the existence of the geocorona was known for a long time, its relevance to X-ray astronomy was realized only after the...