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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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NASA NTRS1986

IRAS observations of active galactic nuclei

IRAS data has been analyzed for 35 radio galaxies and 42 radio-loud quasars, using the coadded survey database. The detection rate is 50 percent with more than 40 percent detected in more than one band. Quasars generally have smooth energy spectra over four or five decades in frequency, consistent with incoherent synchrotron emission from 1 cm to 1 micron. Radio galaxies by contrast have discontinuous spectra, with a large range in the spectral index at IRAS wavelengths. The energy budget shows that the majority of the power per unit bandwidth emerges in the infrared (1-100 microns). The fraction of bolometric luminosity emitted in the infrared is 20-30 percent for the quasars and 40-60 percent for the radio galaxies.

Impey, Chris↗
NASA NTRS1986

A search for narrow band signals with Serendip II - A progress report

Commensal programs for SETI, carried out concurrently with conventional radio astronomical observing programs, can be an attractive and cost-effective means of exploring the large multidimensional search space intrinsic to this effort. An automated commensal system, Serendip II, searches for 0.49-Hz signals in sequential 64,700 Hz bands of the IF of a radio telescope being used for an astronomical observation. Upon detection of a signal with power above a preset threshold, the frequency, power, time, and telescope direction are recorded for later study. The system has been tested at the Hat Creek Radio Astronomy Observatory 85-ft telescope and the NASA-JPL Deep Space Station (DSS 14) 64-m telescope.

Werthimer, D.↗
DOE OSTI2024

Localizing the non-thermal X-ray emission of PSR J2229+6114 from its multi-wavelength pulse profiles

Context.Pulsars are detected over the whole electromagnetic spectrum, from radio wavelengths up to very high energies, in the GeV-TeV range. While the radio emission site for young pulsars is well constrained to occur at altitudes about several percent of the light-cylinder radius andγ-ray emission is believed to be produced in the striped wind, outside the light cylinder, the non-thermal X-ray production site remains unknown. Aims.The aim of this Letter is to localize the non-thermal X-ray emission region based on a multi-wavelength pulse profile fitting for PSR J2229+6114, which stands as a particularly good candidate given its high X-ray brightness. Methods.Based on the geometry deduced from the joint radio andγ-ray pulse profiles, we fixed the magnetic axis inclination angle and the line-of-sight (LoS) inclination angle. However, we left the region of X-ray emission unlocalized, setting it somewhere between the surface and the light cylinder. We localized this region and its extension by fitting the X-ray pulse profile as observed by the NICER,NuSTAR, and RXTE telescopes in the ranges of 2–7 keV, 3–10 keV, and 9.4–22.4 keV, respectively. Results.We constrained the non-thermal X-ray emission to arise from altitudes between 0.2 r L and 0.55 r L wherer L is the light-cylinder radius. The magnetic obliquity is approximatelyα ≈ 45° −50° and the LoS inclination angle isζ ≈ 32° −48°. Conclusions.This Letter is among the first works to offer a tight constraint on the location of non-thermal X-ray emission from pulsars. We plan to apply this procedure to several other promising candidates to confirm this new result.

Astronomy & Astrophysics↗
DOE OSTI2023

The TRAPUM L -band survey for pulsars in Fermi -LAT gamma-ray sources

ABSTRACT More than 100 millisecond pulsars (MSPs) have been discovered in radio observations of gamma-ray sources detected by the Fermi Large Area Telescope (LAT), but hundreds of pulsar-like sources remain unidentified. Here, we present the first results from the targeted survey of Fermi-LAT sources being performed by the Transients and Pulsars with MeerKAT (TRAPUM) Large Survey Project. We observed 79 sources identified as possible gamma-ray pulsar candidates by a Random Forest classification of unassociated sources from the 4FGL catalogue. Each source was observed for 10 min on two separate epochs using MeerKAT’s L-band receiver (856–1712 MHz), with typical pulsed flux density sensitivities of $\sim 100\, \mu$Jy. Nine new MSPs were discovered, eight of which are in binary systems, including two eclipsing redbacks and one system, PSR J1526−2744, that appears to have a white dwarf companion in an unusually compact 5 h orbit. We obtained phase-connected timing solutions for two of these MSPs, enabling the detection of gamma-ray pulsations in the Fermi-LAT data. A follow-up search for continuous gravitational waves from PSR J1526−2744 in Advanced LIGO data using the resulting Fermi-LAT timing ephemeris yielded no detection, but sets an upper limit on the neutron star ellipticity of 2.45 × 10−8. We also detected X-ray emission from the redback PSR J1803−6707 in data from the first eROSITA all-sky survey, likely due to emission from an intrabinary shock.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2022

Magnetar Bursts Due to Alfvén Wave Nonlinear Breakout

The most common form of magnetar activity is short X-ray bursts, with durations from milliseconds to seconds, and luminosities ranging from 10 36 –10 43 erg s -1 . Recently, an X-ray burst from the galactic magnetar SGR 1935+2154 was detected to be coincident with two fast radio burst (FRB) like events from the same source, providing evidence that FRBs may be linked to magnetar bursts. Using fully 3D force-free electrodynamics simulations, we show that such magnetar bursts may be produced by Alfvén waves launched from localized magnetar quakes: a wave packet propagates to the outer magnetosphere, becomes nonlinear, and escapes the magnetosphere, forming an ultra-relativistic ejecta. The ejecta pushes open the magnetospheric field lines, creating current sheets behind it. Magnetic reconnection can happen at these current sheets, leading to plasma energization and X-ray emission. The angular size of the ejecta can be compact, ≲1 sr if the quake launching region is small, ≲0.01 sr at the stellar surface. We discuss implications for the FRBs and the coincident X-ray burst from SGR 1935+2154.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1977

Recent results from the Viking Labeled Release experiment on Mars

The Labeled Release (LR) life detection experiment seeks detection of heterotrophic metabolism by monitoring radio-active gas evolution following the addition of a radioactive nutrient containing seven C-14 labeled organic substrates to surface material. LR results obtained on Mars prior to conjunction showed rapid evolution of radioactive counts upon addition of the nutrient to a fresh surface sample. The responses at both landing sites were quite similar. The additional results summarized in the present paper provide further information on the gas kinetics following a second injection of nutrient and on the effect of 'cold sterilization' of the Martian surface material. Specifically, it is shown that the production of gas from the LR nutrient is remarkably uniform; after reaction approaches completion, addition of more nutrient results in a net loss of the radioactive gas; the reactant in the Mars soil is completely inhibited by heating the soil to 160 C, and is largely inhibited by heating to 46 C. In contrast, exposure to 18 C for 2 sol (1 sol = 24.6 hr) does not appear to inhibit the reaction.

Levin, G. V.↗
NASA NTRS1977

The Tidbinbilla interferometer

This paper describes a technique to detect and identify weak, small-diameter radio sources with flux densities in the millijansky range. An interferometer system is proposed which will use existing 64 m and 24 m antennas of the Tidbinbilla Deep Space Network near Canberra. Design parameters of the system are described, and a schematic is presented with attention to low-noise traveling wave masers, and phase oscillation devices.

Batty, M. J.↗
NASA NTRS1978

A soft X-ray image of the Cygnus Loop SNR

The first true X-ray image of a galactic source is presented. X-ray emission from the Cygnus Loop SNR was recorded with a rocket-borne soft X-ray imaging system having an angular resolution of approximately 10 arcmin (0.1-1.0 keV). The image suggests X-ray production arising from an asymmetrical limb-brightened shell of hot plasma, resulting from a blast wave expanding into the interstellar medium, the inherent inhomogeneity of which is indicated by spatial structure in the image, observed on scale sizes down to approximately 0.25 deg. No evidence for a central, unresolved X-ray source is found and no significant detection made of any of the unresolved radio sources which may be associated with the SNR. Significant spectral variations are observed across the image.

Kayat, M. A.↗
NASA NTRS1981

Low-frequency plasma waves near Saturn

Voyager planetary radio astronomy observations of low frequency emissions detected around the time of closest approach to Saturn and near the outbound ring plane crossing are presented. Near the ring plane an electron density of between 5 and 20 electrons/cu cm at dista

Pedersen, B. M.↗
NASA NTRS1981

First detection of nonflare microwave emissions from the coronae of single late-type dwarf stars

Results are presented of a search for nonflare microwave radiation from the coronae of nearby late-type dwarf stars comparable to the sun: single stars without evidence for either a large wind or circumstellar envelope. The observing program consisted of flux measurements of six stars over a 24-h period with the VLA in the C configuration at a wavelength of 6 cm with 50 MHz bandwidth. Positive detections at 6 cm were made for Chi 1 Ori (0.6 mJy) and the flare star UV Cet (1.55 mJy), and upper limits were obtained for the stars Pi 1 UMa, Xi Boo A, 70 Oph A and Epsilon Eri. It is suggested that Chi 1 Ori, and possibly UV Cet, represent the first detected members of a new class of radio sources which are driven by gyroresonance emission, i.e. cyclotron emission from nonrelativistic Maxwellian electrons.

Gary, D. E.↗
NASA NTRS1986

Boundary conditions for the paleoenvironment: Chemical and physical processes in the pre-solar nebula

The first interstellar hydrocarbon ring, cyclopropenylidene (C3H2) is being studied. Both a survey of galactic sources in several C3H2 transitions and a more detailed study of a subset of these sources are under way. In the latter category is a study of the nearby cold dark cloud TMC-1, which is a potential formation site for solar type stars. A spectra is shown of seven rotational transitions which have been observed at the Five College Radio Astronomy Observatory. Three of these were detected for the first time in any astronomical source: the 3 sub 30 to 2 sub 21 transition at 216 GHz, the 2 sub 21 to 1 sub 10 transition at 122 GHz, and the 1 sub 11 to 0 sub 00 transition at 52 GHz. From the data it is apparent that C3H2 is quite spacially extended in typical interstellar molecular clouds, and that at least in TMC-1 it is one of the most abundant organic molecules.

Irvine, W. M.↗
NASA NTRS1986

Far-infrared properties of optically selected quasars

The far-infrared properties of 10, optically selected quasars were studied on the basis of pointed IRAS observations and ground-based near-infrared and radio measurements. Nine of these quasars were detected in at least three IRAS bands. The flat spectral energy distributions characterizing these optically selected quasars together with large 60-100-micron luminosities suggest that the infrared emission is dominated by nonthermal radiation. Seven of the nine quasars with far-infrared detections were found to have low-frequency turnovers.

Edelson, R. A.↗
NASA NTRS1987

X-rays from the radio halo of M87

The Einstein Observatory and the VLA were used to scan the radio halo of the galaxy M87 to detect the presence, if any, of inverse Compton X-ray (ICX) emissions. The scans revealed a coincidence of an asymmetrical X-ray structure with a luminosity near 4 x 10 to the 41st ergs/sec and dominant symmetrical emission from the hot interstellar gas. The emission can be attributed to ICX if the magnetic field of the proposed halo varies between 3-8 times below equipartition levels of 2-5 micro-gauss, which would imply that the confinement is produced by an outside medium. The necessary characteristics of the confining mechanism are discussed.

Feigelson, E. D.↗
NASA NTRS1987

Beaming of Uranian kilometric radiation and implications for the planetary magnetic field

Radio waves from Uranus at 481.2 kHz detected by Voyager 2 show a strong beaming effect. When the data are analyzed according to the magnetic latitude of the observer in an offset tilted dipole field model, a sharply defined emission beam extending from 25 to 55 deg latitude is evident consistent with a source over the south magnetic pole. The lack of prominent emission from the north magnetic pole can be attributed to the large spatial offset of the magnetic dipole resulting in much lower source frequencies. For proper alignment of the beam, an advance of the dipole axis longitude by 23 deg from the standard model is required. This phase shift is interpreted as the result of higher order magnetic moments producing a skew of the field lines at low altitudes in the polar source region. This conclusion further substantiates models of the interior of Uranus which predict a complex intrinsic field with significant nondipolar contributions to the surface magnetic field.

Barbosa, D. D.↗
NASA NTRS1989

The miniblazar in 3C 273

The compact core of 3C 273 has been studied for over two years using optical photometry and accurate polarimetry. A wealth of polarization behavior, including variable polarization, observed at a level of under 1 percent is described. The results indicate that 3C 273 harbors a weak continuum component having all the characteristic properties of blazars. It is predicted that other compact radio sources with low optical polarization will also be found to harbor miniblazars. The detection of variable polarization in 3C 273 strengthens the link between superluminal motion at radio wavelengths and blazar activity at optical wavelengths.

Impey, C. D.↗
NASA NTRS1991

Ground-based high energy astronomy

The specific aim of the project at hand is to study the changes in amplitude and phase of VLF radio waves to see if we can detect the ionospheric disturbance (the change in electron density) caused by a Gamma-Ray burst. The possible advantages of observing gamma-ray bursts through ionospheric disturbances are better localization of burst directions through a large network of VLF receiving points; measurement of total ionizing fluence of gamma-ray bursts; and comparison with satellite data (GOES and GRO) to derive properties of the ionosphere. There is a major problem here: the ionospheric disturbance caused by a Gamma-Ray burst is at best extremely difficult and at worse impossible to detect. So far only one vent has been detected via this method. Therefore, it was decided to study the ionospheric disturbance caused by solar flares first with the hope that they will teach us how to detect the elusive Gamma-Ray bursts. Much is to be learned about the ionosphere and its reaction to impulsive ionization.

Mcgruder, Charles H., III↗