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Kaaret, Philip

Publications and source records attributed to Kaaret, Philip.

34 records · Page 2
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NASA NTRS2004

Studying X-Ray Binaries with High Frequency Quasi-Periodic Oscillations

The goal of this investigation is to further our understanding of the dynamics of accreting neutron stars and black holes in the hope of using these systems as probes of the physics of strong gravitational fields. The main focus of this work has been a multi-year program of millisecond X-ray timing and spectral observations of accreting compact objects. include imaging of X-ray jets from binaries and the study of extragalactic X-ray binaries. past year. Nine papers were accepted and/or published, as listed below. Seven of these are new since our previous annual report. With the advent of Chandra, we have extended our work to Significant progress was made over the The presentation of several talks and posters at astronomical meetings were supported by this grant. The PI was the lead organizer of "X-Ray Timing 2003: Rossi and Beyond", a major conference held in Cambridge, MA, in November, 2003. A t the conference we reviewed the accomplishments of the Rossi X-Ray Timing Explorer and developed the scientific motivation for a future X-ray timing mission. This conference was well attended and generated a significant amount of interest.

Oliversen, Ronald↗
NASA NTRS2004

Simultaneous X-Ray and Optical Timing Observations of GX 339-4

The goal of this proposal is to perform the first comprehensive study of the correlated X-ray and optical variability of the Galactic accreting black hole candidate GX 339-4 using the X-ray and optical instruments on XMM-Newton. With these observations, we hope to make significant progress in understanding the coupled inflow - outflow system around a persistently accreting stellar mass black hole. The data is now all reduced. This includes the data analysis for all of the instruments on XMM-Newton, the EPIC - PN, the EPIC - MOS, the RGS, and the OM. We are currently preparing the results for publication.

Kaaret, Philip↗
NASA NTRS2003

Simultaneous X-Ray and Optical Timing Observations of GX 339-4

The goal of this proposal is to perform the first comprehensive study of the correlated x-ray and optical variability of the Galactic accreting black hole candidate GX 339-4 using the x-ray and optical instruments on XMM-Newton. With these observations, we hope to make significant progress in understanding the coupled inflow - outflow system around a persistently accreting stellar mass black hole. We are currently analyzing the data. The data analysis is rather complex as it involves all of the instruments on XMM-Newton, the EPIC-PN, the EPIC-MOS, the RGS, and the OM, and our analysis requires study of correlated fast variability in the EPIC-PN and OM. We expect to have results ready to submit for publication within 3 to 4 months.

Kaaret, Philip↗
NASA NTRS1999

"X-Ray Transients in Star-Forming Regions" and "Hard X-Ray Emission from X-Ray Bursters"

This grant funded work on the analysis of data obtained with the Burst and Transient Experiment (BATSE) on the Compton Gamma-Ray Observatory. The goal of the work was to search for hard x-ray transients in star forming regions using the all-sky hard x-ray monitoring capability of BATSE. Our initial work lead to the discovery of a hard x-ray transient, GRO J1849-03. Follow-up observations of this source made with the Wide Field Camera on BeppoSAX showed that the source should be identified with the previously known x-ray pulsar GS 1843-02 which itself is identified with the x-ray source X1845-024 originally discovered with the SAS-3 satellite. Our identification of the source and measurement of the outburst recurrence time, lead to the identification of the source as a Be/X-ray binary with a spin period of 94.8 s and an orbital period of 241 days. The funding was used primarily for partial salary and travel support for John Tomsick, then a graduate student at Columbia University. John Tomsick, now Dr. Tomsick, received his Ph.D. from Columbia University in July 1999, based partially on results obtained under this investigation. He is now a postdoctoral research scientist at the University of California, San Diego.

Halpern, Jules P.↗
NASA NTRS1999

Hard X-Ray Emission from X-Ray Bursters

The scientific goal of this project is to study the hard x-ray emission from x-ray bursters. One target of opportunity observation was made for this investigation during 1997. We obtained 38ks of data on the source 4UI705-44. The project is closely related to "Monitoring x-ray emission from x-ray bursters", and "Long-Term Hard X-Ray Monitoring of X-Ray Bursters."

Halpern, Jules P.↗
NASA NTRS1999

Kilohertz Quasiperiodic Oscillations in Atoll Sources

The scientific goal of this project was to monitor two selected atoll sources to search for quasiperiodic oscillations (QPOs) near 1000 Hz and to study the long evolution of high frequency QPOs and their dependence on other parameters of the system such as x-ray luminosity and spectral state. All of the requested observations were carried out and the data has been analyzed. Three publications have appeared in the Astrophysical Journal using data from this proposal.

Halpern, Jules P.↗
NASA NTRS1999

Long-Term Hard X-Ray Monitoring of X-Ray Bursters

The scientific goal of this project was to monitor a selected sample of x-ray bursters using data from the Burst and Transient Source Experiment (BATSE) on the Compton Gamma-Ray Observatory to characterize the hard x-ray emission of these objects over long time intervals. The project was closely related to "Monitoring x-ray emission from x-ray bursters", NASA project, and "Hard x-ray emission of x-ray bursters", NASA project, and shares publications in common with both of these. These efforts have lead to results directly from the BATSE data and also from Target of Opportunity Observations (TOO) made with the Rossi X-Ray Timing Explorer based on detection of transient hard x-ray outbursts with BATSE. The following papers have used BATSE data or data obtained with BATSE TOO triggers.

Halpern, Jules P.↗
NASA NTRS1999

Monitoring X-Ray Emission from X-Ray Bursters

The scientific goal of this project was to monitor a selected sample of x-ray bursters using data from the All-Sky Monitor (ASM) on the Rossi X-Ray Timing Explorer together with data from the Burst and Transient Source Experiment (BATSE) on the Compton Gamma-Ray Observatory to study the long-term temporal evolution of these sources in the x-ray and hard x-ray bands. The project was closely related to "Long-Term Hard X-Ray Monitoring of X-Ray Bursters", NASA project NAG5-3891, and and "Hard x-ray emission of x-ray bursters", NASA project NAG5-4633, and shares publications in common with both of these. The project involved preparation of software for use in monitoring and then the actual monitoring itself. These efforts have lead to results directly from the ASM data and also from Target of Opportunity Observations (TOO) made with the Rossi X-Ray Timing Explorer based on detection of transient hard x-ray outbursts with the ASM and BATSE.

Halpern, Jules P.↗
NASA NTRS1998

Monitoring X-Ray Emission from X-Ray Bursters

The goal of this investigation was to use the All-Sky Monitor on the Rossi X-Ray Timing Explorer (RXTE) in combination with the Burst and Transient Source Experiment on the Compton Gamma-Ray Observatory to simultaneously measure the x-ray (2-12 keV) and hard x-ray (20-100 keV) emission from x-ray bursters. The investigation was successful. We made the first simultaneous measurement of hard and soft x-ray emission and found a strong anticorrelation of hard and soft x-ray emission from the X-Ray Burster 4U 0614+091. The monitoring performed under this investigation was also important in triggering target of opportunity observations of x-ray bursters made under the investigation hard x-ray emission of x-ray bursters approved for RXTE cycles 1 and 2. These observations lead to a number of papers on high-frequency quasi-periodic oscillations and on hard x-ray emission from the x-ray bursters 4U 0614+091 and 4U 1705-44.

Kaaret, Philip↗
NASA NTRS1997

CGRO Observations

This final report presents an investigation of the CGRO (Compton Gamma Ray Observatory) observations. The investigation includes: Diffuse Gamma-Ray Emission at High Latitudes; and Echoes in X-Ray Novae; A Localized Excess of Gamma-Radiation; Transient Hard X-Ray Emission from Globular Clusters; and A Search for Be/X-Ray Binaries in Hard X-Rays; Hard X-Ray Emission from X-Ray Bursters; X-Ray Transients in Star-Forming Regions; Gamma-ray Emission from Globular Clusters; Shock High Energy Emission from Be-Star/Pulsar System PSR 1259-63m; Gamma-Ray Spectroscopy of Nearby OB Associations; Long Term Hard X-Ray Monitoring of X-Ray Busters; and Periodic Hard X-Ray Emission from GRO J1849-03.

Kaaret, Philip↗
NASA NTRS1997

Gamma-Ray Spectroscopy of Nearby OB Associations

This final report is a summary of the study on gamma ray spectroscopy of nearby OB associations. The goal of this work is to investigate the gamma ray line emission detected with the Compton Telescope (COMPTEL) from the Orion star forming region. This is accomplished by searching for similar emission from other nearby OB associations.

Kaaret, Philip↗
NASA NTRS1995

Gamma-ray emission from globular clusters. Shock high energy emission from the Be-Star/Pulsar System PSR 1259-63. Echoes in x-ray novae

This grant covers work on the Compton phase 3 investigation, 'Shock High Energy Emission from the Be- Star/Pulsar System PSR 1259-63' and cycle 4 investigations 'Diffuse Gamma-Ray Emission at High Latitudes' and 'Echoes in X-Ray Novae'. Work under the investigation 'Diffuse Gamma-Ray Emission at High Latitudes' has lead to the publication of a paper (attached), describing gamma-ray emissivity variations in the northern galactic hemisphere. Using archival EGRET data, we have found a large irregular region of enhanced gamma-ray emissivity at energies greater 100 MeV. This is the first observation of local structure in the gamma-ray emissivity. Work under the investigation 'Echoes in X-Ray Novae' is proceeding with analysis of data from OSSE from the transient source GRO J1655-40. The outburst of this source last fall triggered this Target of Opportunity investigation. Preliminary spectral analysis shows emission out to 600 keV and a pure power low spectrum with no evidence of an exponential cutoff. Work is complete on the analysis of BATSE data from the Be-Star/Pulsar Sustem PSR 1259-63.

Kaaret, Philip↗
NASA NTRS1995

Development of microchannel plate x-ray optics

The goal of this research program was to develop a novel technique for focusing x-rays based on the optical system of a lobster's eye. A lobster eye employs many closely packed reflecting surfaces arranged within a spherical or cylindrical shell. These optics have two unique properties: they have unlimited fields of view and can be manufactured via replication of identical structures. Because the angular resolution is given by the ratio of the size of the individual optical elements to the focal length, optical elements with size on the order of one hundred microns are required to achieve good angular resolution with a compact telescope. We employed anisotropic etching of single crystal silicon wafers for the fabrication of micron-scale optical elements. This technique, commonly referred to as silicon micromachining, is based on silicon fabrication techniques developed by the microelectronics industry. We have succeeded in producing silicon lenses with a geometry suitable for a 1-d focusing x-ray optics. These lenses have an aspect ratio (40:1) suitable for x-ray reflection and have very good optical surface alignment. We have developed a number of process refinements which improved the quality of the lens geometry and the repeatability of the etch process. In addition to the silicon fabrication, an x-ray beam line was constructed at Columbia for testing the optics. Most recently, we have done several experiments to find the fundamental limits that the anisotropic etch process placed on the etched surface roughness.

Kaaret, Philip↗
NASA NTRS1994

Development of microchannel plate x-ray optics

The goal of this research program was to develop a novel technique for focusing x-rays based on the optical system of a lobster's eye. A lobster eye employs many closely packed reflecting surfaces arranged within a spherical or cylindrical shell. These optics have two unique properties: they have unlimited fields of view and can be manufactured via replication of identical structures. Because the angular resolution is given by the ratio of the size of the individual optical elements to the focal length, optical elements with sizes on the order of one hundred microns are required to achieve good angular resolution with a compact telescope. We employed anisotropic etching of single crystal silicon wafers for the fabrication of micron-scale optical elements. This technique, commonly referred to as silicon micromachining, is based on silicon fabrication techniques developed by the microelectronics industry. An anisotropic etchant is a chemical which etches certain silicon crystal planes much more rapidly than others. Using wafers in which the slowly etched crystal planes are aligned perpendicularly to the wafer surface, it is possible to etch a pattern completely through a wafer with very little distortion. Our optics consist of rectangular pores etched completely through group of zone axes (110) oriented silicon wafers. The larger surfaces of the pores (the mirror elements) were aligned with the group of zone axes (111) planes of the crystal perpendicular to the wafer surface. We have succeeded in producing silicon lenses with a geometry suitable for 1-d focusing x-ray optics. These lenses have an aspect ratio (40:1) suitable for x-ray reflection and have very good optical surface alignment. We have developed a number of process refinements which improved the quality of the lens geometry and the repeatability of the etch process. A significant progress was made in obtaining good optical surface quality. The RMS roughness was decreased from 110 A for our initial lenses to 30 A in the final lenses. A further factor of three improvement in surface quality is required for the production of efficient x-ray optics. In addition to the silicon fabrication, an x-ray beam line was constructed at Columbia for testing the optics.

Kaaret, Philip↗
NASA NTRS1991

The photoelectric effect from CsI by polarized soft X-rays

Studies of the polarization dependence of the photoelectric effect produced by soft X-rays from CsI indicate that the geometrical effects in these experiments can often mimic the polarization signature. This paper presents a detailed calculation of these geometrical effects that are produced when the X-ray beam is not precisely aligned on a rotatable plane photocathode. The experimentally observed geometrical effects were used to precisely determine the realignment of the incident beam of polarized X-rays on a rotatable photocathode. The results allow determinations of the true polarization dependence of the photoemission from CsI. It is shown that the photoelectric effect in CsI depends on the polarization state of the X-rays.

Shaw, Ping S.↗
NASA NTRS1990

An imaging photoemission polarimeter for soft X-rays

Results of investigations are reviewed to assess the polarization dependence of photoemission in the optical, UV, and soft X-ray bands, as well as present a design for an imaging photoelectric polarimeter. Data regarding the effect of the dependence in the soft X-ray band are emphasized including the quantity of photons produced by each X-ray. The phase shift encountered in some experiments indicates that a third axis is present; the importance of the phase shift in understanding the vectoral photoeffect is emphasized. Measurements of the pulse height show that this measure is proportional to the number of electrons photoemitted by the incident X-ray. The development of X-ray polarimeters can be significantly improved as a result of the study of polarization sensitivity in the photoelectric effect. The design of a photoelectric polarimeter is presented, and the potential uses for the instrument include measuring the polarization of supernova remnants, AGN, and black hole candidates.

Kaaret, Philip↗