Andrew E. Szymkowiak

A High Spectral Resolution Observation of the Soft X-Ray Diffuse Background with Thermal Detectors

A high spectral resolution observation of the diffuse X-ray background in the 60–1000 eV energy range has been made using an array of 36 1 mm 2 microcalorimeters flown on a sounding rocket. Detector energy resolution ranged from 5 to 12 eV FWHM, and a composite spectrum of � 1 sr of the background centered at l ¼ 90 � , b ¼þ 60 � was obtained with a net resolution of � 9 eV. The target area includes bright 1 keV regions but avoids Loop I and the North Polar Spur. Lines of C vi ,O vii, and O viii are clearly detected with intensities of 5:4 � 2:3, 4:8 � 0:8, and 1:6 � 0:4 photons cm � 2 s � 1 sr � 1 , respectively. The oxygen lines alone account for a majority of the diffuse background observed in the ROSAT R4 band that is not due to resolved extragalactic discrete sources. We also have a positive detection of the Fe-M line complex near 70 eV at an intensity consistent with previous upper limits that indicate substantial gas-phase depletion of iron. We include a detailed description of the instrument and its detectors. Subject headings: instrumentation: detectors — instrumentation: spectrographs — intergalactic medium — space vehicles: instruments — X-rays: diffuse background — X-rays: ISM

The X-ray spectrum of SN 1006

The supernova (SN) of A.D. 1006 represents the brightest in recorded history. The X-ray observations of its remnant appear to be full of puzzles. The present paper has the objective to reevaluate published X-ray data on SN 1006, using detailed nonequilibrium spectral computations and a self-consistent hydrodynamic SNR model. In a summary of the main conclusions, it is pointed out that an observed power-law continuum can be understood as mainly free-free emission from a reverse shock into SN ejecta with an initially uniform density profile. The spectral index is correctly predicted by such a model. Most of the continuum is produced by fully ionized gas in the dense outer layers of ejecta. The X-ray spectrum is not consistent with a solar composition or a uniform composition but is consistent with a layered composition of ejecta containing carbon on the outside, and processed heavy elements on the inside. There is no difficulty in including a large mass of iron.

The Astro-H High Resolution Soft X-Ray Spectrometer

We present the overall design and performance of the Astro-H (Hitomi) Soft X-Ray Spectrometer (SXS). The instrument uses a 36-pixel array of x-ray microcalorimeters at the focus of a grazing-incidence x-ray mirror Soft X-Ray Telescope (SXT) for high-resolution spectroscopy of celestial x-ray sources. The instrument was designed to achieve an energy resolution better than 7 eV over the 0.3-12 keV energy range and operate for more than 3 years in orbit. The actual energy resolution of the instrument is 4-5 eV as demonstrated during extensive ground testing prior to launch and in orbit. The measured mass flow rate of the liquid helium cryogen and initial fill level at launch predict a lifetime of more than 4 years assuming steady mechanical cooler performance. Cryogen-free operation was successfully demonstrated prior to launch. The successful operation of the SXS in orbit, including the first observations of the velocity structure of the Perseus cluster of galaxies, demonstrates the viability and power of this technology as a tool for astrophysics.

The Astro-E2 X-ray spectrometer/EBIT microcalorimeter x-ray spectrometer

The x-ray spectrometer (XRS) instrument is a revolutionary nondispersive spectrometer that will form the basis for the Astro-E2 observatory to be launched in 2005. We have recently installed a flight spare XRS microcalorimeter spectrometer at the EBIT-I and SuperEBIT facility at LLNL replacing the XRS from the earlier Astro-E mission and providing twice the resolving power. The XRS microcalorimeter is an x-ray detector that senses the heat deposited by the incident photon. It achieves a high energy resolution by operating at 0.06   K and by carefully engineering the heat capacity and thermal conductance. The XRS/EBIT instrument has 32 pixels in a square geometry and achieves an energy resolution of 6 eV at 6 keV, with a bandpass from 0.1 to 12 keV (or more at higher operating temperature). The instrument allows detailed studies of the x-ray line emission of laboratory plasmas. The XRS/EBIT also provides an extensive calibration “library” for the Astro-E2 observatory.

The QUEST Large Area CCD Camera

We have designed, constructed, and put into operation a very large area CCD camera that covers the field of view of the 1.2 m Samuel Oschin Schmidt Telescope at the Palomar Observatory. The camera consists of 112 CCDs arranged in a mosaic of four rows with 28 CCDs each. The CCDs are pixel Sarnoff 600 # 2400 thinned, back-illuminated devices with pixels. The camera covers an area of on the

Soft x-ray spectrometer (SXS): The high-resolution cryogenic spectrometer onboard ASTRO-H

We present the development status of the Soft X-ray Spectrometer (SXS) onboard the ASTRO-H mission. The SXS provides the capability of high energy-resolution X-ray spectroscopy of a FWHM energy resolution of < 7eV in the energy range of 0.3 – 10 keV. It utilizes an X-ray micorcalorimeter array operated at 50 mK. The SXS microcalorimeter subsystem is being developed in an EM-FM approach. The EM SXS cryostat was developed and fully tested and, although the design was generally confirmed, several anomalies and problems were found. Among them is the interference of the detector with the micro-vibrations from the mechanical coolers, which is the most difficult one to solve. We have pursued three different countermeasures and two of them seem to be effective. So far we have obtained energy resolutions satisfying the requirement with the FM cryostat.

The X-ray spectrum of Tycho

Baade (1945) has identified Tychos supernova (SN) of A.D. 1572 as Type I, taking into account an analysis of the light curve recorded by Tycho. However, in spite of the obvious interest of Tychos spectrum, to date the spectrum remains poorly understood. The present study is concerned with a reevaluation of the X-ray spectrum of Tycho. Attention is given to detailed nonequilibrium calculations and a self-consistent hydrodynamic model for ejecta consisting of pure heavy elements moving into a uniform external medium. The model provides a satisfactory fit to the spectrum, and avoids any requirement for a large mass of material in Tycho. It is demonstrated that the observed iron line emission is compatible with the presence of perhaps 0.7 solar mass of iron, of which 0.3 solar mass is shocked.

Suzaku Observations of Tycho's Supernova Remnant

Tychos supernova remnant was observed by the XIS and HXD instruments onboard the Suzaku satellite on 2006 June 26-29 for 92 ks. The spectrum up to 30 keV was well fitted with a two-component model, consisting of a power-law with photon index of 2.7 and a thermal bremsstrahlung model with temperature of 4.7 keV. The former component can alternatively be modeled as synchrotron emission from a population of relativistic electrons with an estimated roll-off energy of around 1 keV. In the XIS spectra, in addition to the prominent Fe K_alpha line (6.445 keV), we observe for the first time significant K_alpha line emission from the trace species Cr and Mn at energies of 5.48 keV and 5.95 keV, respectively. Faint K_beta lines from Ca (4.56 keV) and Fe (7.11 keV) are also seen. The ionization states of Cr and Mn, based on their line centroids, are estimated to be similar to that of Fe K_alpha (Fe XV or XVI).

IRAS observations of supernova remnants - a comparison between their infrared and X-ray cooling rates

A comparison is presented between the total IR and X-ray cooling rates of nine selected Galactic supernova remnants. The observed IR-to-X-ray cooling ratio (IRX ratio) values are larger than unity for most remnants, ranging from five for the adiabatic remnant Puppis A, to about 1000 for RCW 86. Most of the observed IR emission from the remnants can be attributed to thermal emission from dust collisionally heated by the shocked plasma. A comparison between the theoretical and observed IRX ratio shows that only two of the nine remnants have IRX ratios within a factor of about three of the expected value. Puppis A, Kepler, Tycho, and SN 1006 have IRX ratios that are significantly smaller than the theoretically predicted value, suggesting that the dust is significantly depleted in the ambient medium into which they are expanding. 41 references.

M2K: II. A Triple-Planet System Orbiting HIP 57274

Doppler observations from Keck Observatory have revealed a triple-planet system orbiting the nearby K4V star, HIP 57274. The inner planet, HIP 57274b, is a super-Earth with M sin i = 11.6 M-circle plus (0.036 M-Jup), an orbital period of 8.135 +/- 0.004 days, and slightly eccentric orbit e = 0.19 +/- 0.1. We calculate a transit probability of 6.5% for the inner planet. The second planet has M sin i = 0.4 M-Jup with an orbital period of 32.0 +/- 0.02 days in a nearly circular orbit (e = 0.05 +/- 0.03). The third planet has M sin i = 0.53 M-Jup with an orbital period of 432 +/- 8 days (1.18 years) and an eccentricity e = 0.23 +/- 0.03. This discovery adds to the number of super-Earth mass planets with M sin i < 12 M-circle plus that have been detected with Doppler surveys. We find that 56% +/- 18% of super-Earths are members of multi-planet systems. This is certainly a lower limit because of observational detectability limits, yet significantly higher than the fraction of Jupiter mass exoplanets, 20% +/- 8%, that are members of Doppler-detected, multi-planet systems.