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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 NTRS2008

The Swift Burst and Transient Telescope (BAT)

The Swift Burst and Transient telescope (BAT) has surveyed the entire sky for the last 3.5 years obtaining the first sensitive all sky survey of the 14-195 kev sky. At high galactic latitudes the vast majority of the detected sources are AGN. Since hard x-rays penetrate all but Compton thick obscuring material (Column densities of 1.6324 atms/sq cm) this survey is unbiased with respect to obscuration, host galaxy type, optical , radio or IR properties. We will present results on the broad band x-ray properties, the nature of the host galaxies, the luminosity function and will discuss a few of the optical, IR and x-ray results in detail.

Mushotzky, Richard↗
NASA NTRS2009

The Swift BAT Hard X-ray Survey - A New Window on the Local AGN Universe

The Swift Burst and Transient telescope (BAT) has surveyed the entire sky for the last 3.5 years obtaining the first sensitive all sky survey of the 14-195 keV sky. At high galactic latitudes the vast majority of the detected sources are AGN. Since hard x-rays penetrate all but Compton thick obscuring material (Column densities of 1.6E24 atms/cm2) this survey is unbiased with respect to obscuration, host galaxy type, optical , radio or IR properties. We will present results on the broad band x-ray properties, the nature of the host galaxies, the luminosity function and will discuss a few of the optical, IR and x-ray results in detail.

Mushotzky, Richard↗
NASA NTRS1983

Photometry of resolved galaxies. II - Sextans A

Luminosity functions and color-magnitude diagrams are given for 652 stars in the Sextans A dwarf irregular galaxy, and they are compared with other Local Group galaxies. The brightest red and blue stars presently determined are in agreement with those of Sandage and Carlson (1982), and a group of red stars is identified which may be analogous to the bright carbon star population recently found in the Magellanic Clouds. While the similarity of Sextans A's luminosity function with those of the LMC and the Milky Way is in keeping with a universal luminosity function, stellar mass function and birthrate resemble those of the SMC. Per unit gas mass, Sextans A has a birthrate almost identical to the SMC, suggesting that the mean age of stars in Sextans A is significantly less than of those in the Magellanic Clouds.

Hoessel, J. G.↗
NASA NTRS1987

Primeval galaxies and cold dark matter

In the context of the cold dark matter theory for the large-scale matter distribution, the onset of galaxy formation is a gradual process, with star formation being initiated at z = about 10 and reaching a peak for luminous galaxies at z = about 1. The mass function of galaxy cores matches the observed quasar luminosity function at z = 2-3. Primeval galaxies are envisaged as a collection of many interacting and merging clumps, attaining a peak luminosity that is an order of magnitude below that achieved in models in which galaxy formation is initiated abruptly. Hence, ongoing searches for primeval galaxies would not necessarily have been successful unless they are designed to find moderately low-luminosity, low-surface-brigtness extended objects at low redshift.

Silk, Joseph↗
NASA NTRS1987

A catalog of galaxies in Hercules from the Palomar Sky Survey and the Minnesota Automated Plate Scanner

The development of galaxies catalogs from the Palomar Sky Survey using the Minnesota Automated Plate Scanner (APS) is examined. The design and operation of APS are described. The algorithm used to distinguish stars from galaxies is discussed, and the completeness and confusion of the algorithm as a function of magnitude are estimated. The quality of the photometric calibration for galaxy magnitudes and surface-brightness thresholds is evaluated. The relation between the distribution of colors and morphological types is studied. The luminosity functions for Hercules galaxies are calculated and presented. The catalog generated using the APS is 80 percent complete; photometry good to 0.23 mag rms is possible; and J-F colors are good to 0.17 mag rms.

Dickey, John M.↗
NASA NTRS1993

Resolved stars in nearby galaxies: Ground-based photometry of M81

Using the Canada-France-Hawaii Telescope (CFHT) we have obtained three closely spaced epochs of calibrated Blue Violet Red Infrared (BVRI) CCD imaging of two fields in M81, each known to contain a thirty-day Cepheid. Calibrated BVRI photometry of the brightest stars in these fields is presented. The slope of the luminosity function from the brightest 3-4 mag of the main-sequence blue plume is consistent with similar determinations of the apparent luminosity function in other resolved galaxies, thereby removing the one potential deviation from universality noted by Freedman in a photographic study of luminosity functions in nearby resolved galaxies. Under the assumption that the two Cepheids are representative, a reddening-law fit to the multiwavelength BVRI period-luminosity moduli give a true distance modulus of (m-M)sub 0 = 27.79 mag for M81, corresponding to a linear distance of 3.6 Mpc. An error analysis shows that the derived true distance modulus has a random error of +/- 0.28 mag (due to the photometric uncertainties in the BVRI data), with a systematic uncertainty of +/- 0.10 mag (accounting for the combined effects of unknown phasing of the data points, and the unknown positioning of these particular stars within the Cepheid instabiliy strip).

Madore, Barry F.↗
NASA NTRS1987

A redshift survey of IRAS galaxies

Results are presented from a redshift survey of all 72 galaxies detected by IRAS in Band 3 at flux levels equal to or greater then 2 Jy. The luminosity function at the high luminosity end is proportional to L sup -2, however, a flattening was observed at the low luminosity end indicating that a single power law is not a good description of the entire luminosity function. Only three galaxies in the sample have emission line spectra indicative of AGN's, suggesting that, at least in nearby galaxies, unobscured nuclear activity is not a strong contributor to the far infrared flux. Comparisons between the selected IRAS galaxies and an optically complete sample taken from the CfA redshift survey show that they are more narrowly distributed than those optically selected, in the sence that the IRAS sample includes few galaxies of low absolute blue luminosity. It was also found that the space distributions of the two samples differ: the density enhancement or IRAS galaxies is only approx. 1/3 that of the optically selected galaxies in the core of the Coma cluster.

Smith, Beverly J.↗
NASA NTRS2002

Emission Line Galaxies in the STIS Parallel Survey II: Star Formation Density

We present the luminosity function of [OII]-emitting galaxies at a median redshift of z = 0.9, as measured in the deep spectroscopic data in the STIS Parallel Survey (SPS). The luminosity function shows strong evolution from the local value, as expected. By using random lines of sight, the SPS measurement complements previous deep single field studies. We calculate the density of inferred star formation at this redshift by converting from [OII] to H(alpha) line flux as a function of absolute magnitude and find rho = 0.052 +/- 0.017 Solar mass/yr Mpc(sup -3) at a median redshift z approx. 0.9 within the range 0.46 less than z less than 1.415 (H(sub 0) = 50 km/s Mpc(sup -l), Omega(sub M) = 1.0, Omega(sub lambda) = 0.0). This density is consistent with a (1 + z)(sup )4 evolution in global star formation since z approx. 1. To reconcile the density with similar measurements made by surveys targeting H(alpha) may require substantial extinction correction.

Teplitz, Harry I.↗
NASA NTRS1990

Dust obscuration by an evolving galaxy population

The effect of an evolving luminosity function (LF) on the ability of foreground galaxies to obscure background sources is discussed, using the Press-Schechter/CDM standard evolving LF model. Galaxies are modeled as simplified versions of local spirals and Poisson statistics are used to estimate the fraction of sky covered by intervening dusty galaxies and the mean optical depths due to these galaxies. The results are compared to those obtained in the case of nonevolving luminosity function in a low-density universe. It is found that evolution of the galaxy LF does not allow the quasar dust obscuration hypothesis to be sustained for dust disks with plausible sizes. Even in a low-density universe, where evolution at z = less than 10 is unimportant, large disk radii are needed to achieve the desired obscuring effect. The mean fraction of sky covered is presented as a function of the redshift z along with adequate diagram illustrations.

Najita, Joan↗
NASA NTRS2011

The Very Local Universe in X-Rays

There are many open questions in X-ray observations of the Galactic neighborhood and nearby galaxies, such as the properties of the hot ISM and accreting sources, the X-ray/star-formation rate correlation and how the X-ray luminosity function of starburst galaxies. We discuss how these would be addressed by very wide-area (> 100 sq. deg.) X-ray surveys and upcoming X-ray missions. In particular planned NuStar observations of the Galaxy and nearby galaxies will be highlighted.

Ptak, A.↗
DOE OSTI2025

ODIN: Probing the LAE Ly α Luminosity Function across Cosmic Time and Different Environments

The ubiquity and relative ease of discovery make 2 ≲ z ≲ 5 Lyα emitting galaxies (LAEs) ideal tracers for large-scale structure of the distant Universe. In addition, because Lyα is a resonance line, but frequently observed at large equivalent width, it is potentially a probe of galaxy evolution. The LAE Lyα luminosity function (LF) is an essential measurement for making progress on both of these topics. Although several studies have computed the LAE LF, very few have delved into how the function varies with environment. The large area and depth of the One-hundred-deg 2 DECam Imaging in Narrowbands (ODIN) survey makes such measurements possible at the cosmic noon redshifts of z ∼ 2.4, 3.1, and 4.5. In this initial work, we present algorithms needed to rigorously compute the LAE LF, and test them on the ∼16,000 ODIN LAEs found in the extended COSMOS field. Using these limited samples, we find weak evidence that protocluster environments suppress the numbers of faint LAEs compared to the field. We also find that the LF decreases in number density and evolves towards a steeper faint-end slope over cosmic time from z ∼ 4.5 to z ∼ 2.4.

Lyman-alpha galaxies↗
NASA NTRS1993

Energy distributions of radio galaxies

Far-infrared observations of 140 radio galaxies which span a range of over four orders of magnitude in radio power, (from weak nuclear sources in nearby galaxies, to powerful FR II doubled lobed sources at moderate redshift) are presented. The strength of the far-infrared emission is more closely correlated with core than total radio emission. Far-infrared emission in radio galaxies represents star formation that is more closely tied to the active nucleus than to the global properties of the galaxy. The far-infrared luminosity function shows good continuity between radio galaxies and radio loud quasars.

Impey, Chris↗
NASA NTRS2012

The Herschel Multi-tiered Extragalactic Survey: HerMES

The Herschel Multi-tiered Extragalactic Survey, HerMES, is a legacy program designed to map a set of nested fields totalling approx. 380 deg(exp 2). Fields range in size from 0.01 to approx. 20 deg (exp 2), using Herschel-SPIRE (at 250, 350 and 500 micron), and Herschel-PACS (at 100 and 160 micron), with an additional wider component of 270 deg. (exp. 2) with SPIRE alone. These bands cover the peak of the redshifted thermal spectral energy distribution from interstellar dust and thus capture the re-processed optical and ultra-violet radiation from star formation that has been absorbed by dust, and are critical for forming a complete multi-wavelength understanding of galaxy formation and evolution. The survey will detect of order 100,000 galaxies at 5-sigma in some of the best studied fields in the sky. Additionally, HerMES is closely coordinated with the PACS Evolutionary Probe survey. Making maximum use of the full spectrum of ancillary data, from radio to X-ray wavelengths, it is designed to: facilitate redshift determination; rapidly identify unusual objects; and understand the relationships between thermal emission from dust and other processes. Scientific questions HerMES will be used to answer include: the total infrared emission of galaxies; the evolution of the luminosity function; the clustering properties of dusty galaxies; and the properties of populations of galaxies which lie below the confusion limit through lensing and statistical techniques. This paper defines the survey observations and data products, outlines the primary scientific goals of the HerMES team, and reviews some of the early results.

multi-tiered↗
NASA NTRS2013

The Herschel* PEP-HERMES Luminosity Function- I. Probing the Evolution of PACS Selected Galaxies to z approx. equal to 4

We exploit the deep and extended far-IR data sets (at 70, 100 and 160 μm) of the Herschel Guaranteed Time Observation (GTO) PACS Evolutionary Probe (PEP) Survey, in combination with the Herschel Multi-tiered Extragalactic Survey data at 250, 350 and 500 μm, to derive the evolution of the rest-frame 35-, 60-, 90- and total infrared (IR) luminosity functions (LFs) up to z ∼ 4.We detect very strong luminosity evolution for the total IR LF (LIR ∝ (1 + z)(sup 3.55 +/- 0.10) up to z ∼ 2, and ∝ (1 + z)(sup 1.62 +/- 0.51) at 2 less than z less than approximately 4) combined with a density evolution (∝ (1 + z)(sup −0.57 +/- 0.22) up to z ∼ 1 and ∝ (1 + z)(sup −3.92 +/- 0.34) at 1 less than z less than approximately 4). In agreement with previous findings, the IR luminosity density (ρIR) increases steeply to z ∼ 1, then flattens between z ∼ 1 and z ∼ 3 to decrease at z greater than approximately 3. Galaxies with different spectral energy distributions, masses and specific star formation rates (SFRs) evolve in very different ways and this large and deep statistical sample is the first one allowing us to separately study the different evolutionary behaviours of the individual IR populations contributing to ρIR. Galaxies occupying the well-established SFR-stellar mass main sequence (MS) are found to dominate both the total IR LF and ρIR at all redshifts, with the contribution from off-MS sources (≥0.6 dex above MS) being nearly constant (∼20 per cent of the total ρIR) and showing no significant signs of increase with increasing z over the whole 0.8 < z <2.2 range. Sources with mass in the range 10 ≤ log(M/solar mass) ≤ 11 are found to dominate the total IR LF, with more massive galaxies prevailing at the bright end of the high-z (greater than approximately 2) LF. A two-fold evolutionary scheme for IR galaxies is envisaged: on the one hand, a starburst-dominated phase in which the Super Massive Black Holes (SMBH) grows and is obscured by dust (possibly triggered by a major merging event), is followed by an AGN-dominated phase, then evolving towards a local elliptical. On the other hand, moderately star-forming galaxies containing a low-luminosity AGN have various properties suggesting they are good candidates for systems in a transition phase preceding the formation of steady spiral galaxies.

Herschel↗
NASA NTRS1981

Very dusty galaxies

The existence of a significant population of dust shrouded galaxies that do not emit much optical light but instead are primarily infrared sources is considered. It is noted that if very dusty galaxies are assumed to have a luminosity function similar to that of normal galaxies, then current observations seem to show that there are not more dusty galaxies than normal objects. Until more extensive infrared observations are obtained, however, it seems at least possible, though perhaps unlikely, that there are in fact a significant number of dusty galaxies.

Jura, M.↗
NASA NTRS1989

Planetary nebulae as standard candles. IV - A test in the Leo I group

In this paper, PN are used to determine accurate distances to three galaxies in the Leo I group - The E0 giant elliptical NGC 3379, its optical companion, the SB0 spiral NGC 3384, and the smaller E6 elliptical NGC 3377. In all three galaxies, the luminosity-specific PN number densities are roughly the same, and the derived stellar death rates are in remarkable agreement with the predictions of stellar evolution theory. It is shown that the shape of the forbidden O III 5007 A PN luminosity function is the same in each galaxy and indistinguishable from that observed in M31 and M81. It is concluded that the PN luminosity function is an excellent standard candle for early-type galaxies.

Ciardullo, Robin↗