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NASA NTRS2007

First X-ray Observations of the Young Pulsar J1357-6429

The first short Chandra and XMM-Newton observations of the young and energetic pulsar J1357-6429 provided strong indications of a tail-like pulsar-wind nebula associated with this object, as well as strong pulsations of its X-ray flux with a pulsed fraction above 40% and a thermal component dominating at lower photon energies (below 2 keV). The elongated nebular is very compact in size. about 1" x 1.5" and might be interpreted as a pulsar jet. The thermal radiation is most plausibly emitted from the entire neutron star surface of an effective temperature about 1 MK covered with a magnetized hydrogen atmosphere At higher energies the pulsar's emission is of a nonthermal (magnetospheric) origin, with a power-law spectrum of a photon index Gamma approx. equals 1.1. This makes the X-ray properties of PSR J1357-6429 very similar to those of the youngest pulsars J1119-6127 and Vela with a detected thermal radiation.

Zavlin, Vyacheslav E.↗
NASA NTRS2007

The Hottest Horizontal-Branch Stars in Omega Centauri: Late Hot Flasher vs. Helium Enrichment

UV observations of some massive globular clusters uncovered a significant population of very hot stars below the hot end of the horizontal branch (HB), the so-called blue hook stars. This feature might be explained either by the late hot flasher scenario here stars experience the helium flash while on the white dwarf cooling curve or by the helium-rich sub-population recently postulated to exist in some clusters. Spectroscopic analyses of blue hook stars in omega Cen and NGC 2808 support the late hot flasher scenario, but the stars contain much less helium than expected and the predicted C, N enrichment could not be verified from existing data. We want to determine effective temperatures, surface gravities and abundances of He, C, N in blue hook and canonical extreme horizontal branch (EHB) star candidates. Moderately high resolution spectra of stars at the hot end of the blue horizontal branch in the globular cluster omega Cen were analysed for atmospheric parameters (T(sub eff), log g) and abundances using LTE and Non-LTE model atmospheres. In the temperature range 30,000 K to 50,000 K we find that 37% of our stars are helium-poor (log nHe/nH less than -2), 49% have solar helium abundance within a factor of 3 (-1.5 less than or equal to log nHe/nH less than or equal to -0.5) and 14% are helium rich (log nHe/nH greater than -0.4). We also find carbon enrichment in step with helium enrichment, with a maximum carbon enrichment of 3% by mass. At least 30% of the hottest HB stars in omega Centauri show helium abundances well above the predictions from the helium enrichment scenario (Y = 0.42 corresponding to log nHe/nH approximately equal to -0.74). In addition the most helium-rich stars show strong carbon enrichment as predicted by the late hot flasher scenario. We conclude that the helium-rich HB stars in omega Cen cannot be explained solely by the helium-enrichment scenario invoked to explain the blue main sequence.

Moehler, S.↗
NASA NTRS2008

Partitioning of Phosphorus and Molybdenum between the Earth's Mantle and Core and the Conditions of Core Formation

There are several hypotheses on the specific processes that might have occurred during the formation of the Earth. One hypothesis that has been proposed is that early in the Earth's formation, there was a magma ocean present, and within this body, siderophile elements separated out of the silicate liquid to form the metal core. This study addresses this hypothesis. P and Mo are moderately siderophile elements that are present in both the mantle and the core. The concentrations of P and Mo in silicate vs. metal can be measured and in turn used to determine the temperatures, pressures, oxygen fugacity and melt composition required to achieve the same concentrations as observed in the mantle. The data here include eight experiments examining the partitioning of P and Mo between metallic liquid and silicate liquid. The purpose of the experiments has been to gain a greater understanding of core-mantle separation during the Earth formation process and examines temperature effect on P and Mo, which has not been systematically studied before.

Acuff, K. M.↗
NASA NTRS2005

A Mid-Infrared Imaging Survey of Embedded Young Stellar Objects in the (rho) Ophiuchi Cloud Core

Results of a comprehensive, new, ground-based mid-infrared imaging survey of the young stellar population of the (rho) Ophiuchi cloud are presented. Data were acquired at the Palomar 5m and at the Keck 10m telescopes with the MIRLIN and LWS instruments, at 0'.5 and 0'.25 resolutions, respectively. Of 172 survey objects, 85 were detected. Among the 22 multiple systems observed, 15 were resolved and their individual component fluxes determined. A plot of the frequency distribution of the detected objects with SED spectral slope shows that YSOs spend approx.4 x 10(exp 5) yr in the flat-spectrum phase, clearing out their remnant infall envelopes. Mid-infrared variability is found among a significant fraction of the surveyed objects and is found to occur for all SED classes with optically thick disks. Large-amplitude near-infrared variability, also found for all SED classes with optically thick disks, seems to occur with somewhat higher frequency at the earlier evolutionary stages. Although a general trend of mid-infrared excess and near-infrared veiling exists progressing through SED classes, with Class I objects generally exhibiting r(sub K) >= 1, flat-spectrum objects with r(sub K) >= 0.58, and Class III objects with r(sub K) =0, Class II objects exhibit the widest range of r(sub K) values, ranging from 0 <= r(sub K) <= 4.5. However, the highly variable value of veiling that a single source can exhibit in any of the SED classes in which active disk accretion can take place is striking and is direct observational evidence for highly time-variable accretion activity in disks. Finally, by comparing mid-infrared versus near-infrared excesses in a subsample with well-determined effective temperatures and extinction values, disk-clearing mechanisms are explored. The results are consistent with disk clearing proceeding from the inside out.

planetary systems↗
NASA NTRS2008

X-Ray Source Motions and Their Implications for Flare Models

RHESSI observations have revealed a downward contraction of solar flare loops followed by upward expansion. In some flares a pair of above-the-looptop sources is observed, one just above the top of the cooler flare loops and the other a discrete source well above the looptops characterized by an effective temperature gradient increasing toward lower altitudes. In one flare the higher, temperature-inverted coronal source sped outward at a speed consistent with that of a coronal mass ejection associated with the flare. In some flares with minimal preheating (early impulsive flares), nonthermal X-ray sources have been observed to propagate downward and then upward along the legs of the flare loop. I will discuss the implications of all of these X-ray source motions for flare models, and their use as diagnostics of the evolution of the physical conditions in flares.

Holman, Gordon D.↗
NASA NTRS2007

The Operation and Evolution of the Swift X-ray Telescope

The Swift X-ray Telescope (XRT) is a CCD based X-ray telescope designed for localization, spectroscopy and long term light curve monitoring of Gamma-Ray Bursts and their X-ray afterglows. Since the launch of Swift in November 2004, the XRT has undergone significant evolution in the way it is operated. Shortly after launch there was a failure of the thermo-electric cooler on the XRT CCD, which led to the XRT team being required to devise a method of keeping the XRT CCD temperature below 50C utilizing only passive cooling by minimizing the exposure of the XRT radiator to the Earth. We present in this paper an update on how the modeling of this passive cooling method has improved in first -1000 days since the method was devised, and the success rate of this method in day-to-day planning. We also discuss the changes to the operational modes and onboard software of the XRT. These changes include improved rapid data product generation in order to improve speed of rapid Gamma-Ray Burst response and localization to the community; changes to the way XRT observation modes are chosen in order to better fine tune data aquisition to a particular science goal; reduction of "mode switching" caused by the contamination of the CCD by Earth light or high temperature effects.

Kennea, Jamie↗
NASA NTRS2009

A New Spectroscopic and Interferometric Study of the Young Stellar Object V645 Cyg

Aims. We present the results of high-resolution optical spectroscopy, low-resolution near-IR spectroscopy and near-infrared speckle interferometry of the massive young stellar object candidate V645 Cyg that were taken in order to refine its fundamental parameters and properties of its circumstellar envelope. Methods. Speckle interferometry in the H- and K-bands and an optical spectrum in the range 5200-6680 A with a spectral resolving power of R = 60000 were obtained at the 6 m telescope of the Russian Academy of Sciences. Another optical spectrum in the range 4300-10500 A with R = 79000 was obtained at the 3.6m CFHT. A low-resolution spectrum in the ranges 0.46-1.4 and 1.4-2.5 microns with a R approx. 800 and approx. 700, respectively, were obtained at the 3m Shain telescope of the Lick Observatory. Results. Using a new kinematic method based on non-linear modeling of the neutral hydrogen density profile in the direction toward the object, we suggest a new a distance D = 4.2+/-0.2 kpc. We also suggest a new estimate for the star's effective temperature, T(sub eff) approx. 25000 K. We have resolved the object in both H- and K-bands. Using a two-component ring fit, we derived a compact component size of 18 mas and 15 mas in the H- and K-band, respectively, which correspond to 37 and 33 AU at the new distance. Analysis of our and previously published data shows a approx. 2 mag drop of the near-infrared brightness of V645 Cyg in the beginning of the 1980 s. At the same time, the cometary nebular condensation N1 seems to fade in this wavelength range with respect to the N0 object, which represent the star with a nearly pole-on optically-thick disk and an optically-thin envelope. Conclusions. We conclude that V645 Cyg is a young massive main-sequence star, which recently emerged from its cocoon. and already passed the protostellar accretion stage. The presence of accretion is not necessary to account for the high observed luminosity of (2.6) x 10(exp 4) Solar Mass/yr. The receding part of a strong, mostly uniform outflow with a terminal velocity of approx.800 km/s is only blocked from view far from the star, where forbidden lines form. The near-infrared size of the source is consistent with the dust sublimation distance near this hot and luminous star and is the largest among young stellar objects observed interferometrically to-date.

Miroshinichenko, A. S.↗
NASA NTRS2009

Astrometry With the Hubble Space Telescope: Trigonometric Parallaxes of Planetary Nebula Nuclei NGC 6853, NGC 7293, ABELL 31, and DeHt 5

We present absolute parallaxes and relative proper motions for the central stars of the planetary nebulae NGC 6853 (The Dumbbell), NGC 7293 (The Helix), Abell 31, and DeHt 5. This paper details our reduction and analysis using DeHt 5 as an example. We obtain these planetary nebula nuclei (PNNi) parallaxes with astrometric data from Fine Guidance Sensors FGS 1r and FGS 3, white-light interferometers on the Hubble Space Telescope. Proper motions, spectral classifications and VJHKT2M and DDO51 photometry of the stars comprising the astrometric reference frames provide spectrophotometric estimates of reference star absolute parallaxes. Introducing these into our model as observations with error, we determine absolute parallaxes for each PNN. Weighted averaging with previous independent parallax measurements yields an average parallax precision, sigma (sub pi)/ pi = 5%. Derived distances are: d(sub NGC6853) = 405(exp +28 sub -25) pc, d(sub NGC7293) = 216(exp +14 sub -12) pc, d(sub Abell31) = 621(exp +91 sub -70) pc, and d(sub DeHt5) = 345(exp +19 sub -17) pc. These PNNi distances are all smaller than previously derived from spectroscopic analyses of the central stars. To obtain absolute magnitudes from these distances requires estimates of interstellar extinction. We average extinction measurements culled from the literature, from reddening based on PNNi intrinsic colors derived from model SEDs, and an assumption that each PNN experiences the same rate of extinction as a function of distance as do the reference stars nearest (in angular separation) to each central star. We also apply Lutz-Kelker bias corrections. The absolute magnitudes and effective temperatures permit estimates of PNNi radii through both the Stefan-Boltzmann relation and Eddington fluxes. Comparing absolute magnitudes with post-AGB models provides mass estimates. Masses cluster around 0.57 solar Mass, close to the peak of the white dwarf mass distribution. Adding a few more PNNi with well-determined distances and masses, we compare all the PNNi with cooler white dwarfs of similar mass, and confirm, as expected, that PNNi have larger radii than white dwarfs that have reached their final cooling tracks.

STARS↗
NASA NTRS2010

The Hot Horizontal-Branch Stars in omega Centauri

Context. UV observations of some massive globular clusters have revealed a significant population of stars hotter and fainter than the hot end of the horizontal branch (HB), the so-called blue hook stars. This feature might be explained either by the late hot flasher scenario where stars experience the helium flash while on the white dwarf cooling curve or by the progeny of the helium-enriched sub-population recently postulated to exist in some clusters. Previous spectroscopic analyses of blue hook stars in co Cen and NGC 2808 support the late hot flasher scenario, but the stars contain much less helium than expected and the predicted C, N enrichment could not be verified. Aims. We compare observed effective temperatures, surface gravities, helium abundances, and carbon line strengths (where detectable) of our targets stars to the predictions of the two scenarios. Methods. Moderately high resolution spectra of hot HB stars in the globular cluster omega-Cen were analysed for radial velocity variations, atmospheric parameters and abundances using LTE and non-LTE model atmospheres. Results. We find no evidence for close binaries among our target stars. All stars below 30 000 K are helium-poor and very similar to HB stars observed in that temperature range in other globular clusters. In the temperature range 30000 K to 50000 K we find that 28% of our stars are helium-poor (log ((sup n)He/(sup n )H)< - 1.6), while 72% have roughly solar or super-solar helium abundance (log ((sup n)He/(sup n )H) >/= -1.5). We also find carbon enrichment strongly correlated with helium enrichment, with a maximum carbon enrichment of 3% by mass. Conclusions. The strong carbon enrichment in tandem with helium enrichment is predicted by the late hot flasher scenario, but not by the helium-enrichment scenario. We conclude that the helium-rich HB stars in omega-Cen cannot be explained solely by the helium-enrichment scenario invoked to explain the blue main sequence.

Moehler, S.↗
NASA NTRS2010

First Detection of the [O(sub III)] 88 Micrometers Line at High Redshifts: Characterizing the Starburst and Narrow-Line Regions in Extreme Luminosity Systems

We have made the first detections of the 88 micrometers [O(sub III)] line from galaxies in the early universe, detecting the line from the lensed active galactic nucleus (AGN)/starburst composite systems APM 08279+5255 at z 3.911 and SMM J02399-0136 at z = 2.8076. The line is exceptionally bright from both systems, with apparent (lensed) luminosities approx.10(exp 11) Solar Luminosity, For APM 08279, the [O(sub III)] line flux can be modeled in a star formation paradigm, with the stellar radiation field dominated by stars with effective temperatures, T(sub eff) > 36,000 K, similar to the starburst found in M82. The model implies approx.35% of the total far-IR luminosity of the system is generated by the starburst, with the remainder arising from dust heated by the AGN. The 881,tm line can also be generated in the narrow-line region of the AGN if gas densities are around a few 1000 cu cm. For SMM J02399, the [O(sub III)] line likely arises from HII regions formed by hot (T(sub eff) > 40,000 K) young stars in a massive starburst that dominates the far-IR luminosity of the system. The present work demonstrates the utility of the [O(sub III)] line for characterizing starbursts and AGN within galaxies in the early universe. These are the first detections of this astrophysically important line from galaxies beyond a redshift of 0.05.s

Ferkinhoff, C.↗
NASA NTRS2010

A Principal Component-Based Radiative Transfer Forward Model (PCRTM) for Vertically in Homogeneous Cloud

A principal-component based radiative transfer model (PCRTM) is developed for simulating the infrared spectral radiance at the top of the atmosphere (TOA). The PCRTM approach removes the redundancy in radiative transfer calculation in high resolution infrared spectra, and saves significant amount of computational time with great accuracy. In PCRTM, both ice and water clouds are treated as effective transmissivity and reflectivity stored in a pre-calculated lookup tables. These quantities are calculated using cloud single scattering properties such as cloud optical depth, cloud particle size, cloud phase, etc. The cloud can be inserted into any pressure layer in the PCRTM model (up to 100 layers). The effective temperature of each cloud layer is treated as a function of its optical depth. To test the accuracy of this approximation, the results are compared with the more rigorous DISORT model, which treats cloud as a plane parallel layer. The root-mean-square error of PCRTM, with respect to DISORT results, is generally less than 0.5 K in brightness temperature. However, the CPU time required by PCRTM was approximately two orders of magnitude less than that required by DISORT.

Li, Hui↗
NASA NTRS2010

Using Remote Sensing Data to Evaluate Habitat Loss in the Mobile, Galveston, and Tampa Bay Watersheds

The Gulf of Mexico has experienced dramatic wetland habitat area losses over the last two centuries. These losses not only damage species diversity, but contribute to water quality, flood control, and aspects of the Gulf coast economy. Overall wetland losses since the 1950s were examined using land cover/land use (LCLU) change analysis in three Gulf coast watershed regions: Mobile Bay, Galveston Bay, and Tampa Bay. Two primary causes of this loss, LCLU change and climate change, were then assessed using LCLU maps, U.S. census population data, and available current and historical climate data from NOAA. Sea level rise, precipitation, and temperature effects were addressed, with emphasis on analysis of the effects of sea level rise on salt marsh degradation. Ecological impacts of wetland loss, including fishery depletion, eutrophication, and hypoxia were addressed using existing literature and data available from NOAA. These ecological consequences in turn have had an affect on the Gulf coast economy, which was analyzed using fishery data and addressing public health impacts of changes in the environment caused by wetland habitat loss. While recent federal and state efforts to reduce wetland habitat loss have been relatively successful, this study implies a need for more aggressive action in the Gulf coast area, as the effects of wetland loss reach far beyond individual wetland systems themselves to the Gulf of Mexico as a whole.

Steffen, Morgan↗
NASA NTRS2010

Massive Star Formation of the SGR a East H (sub II) Regions Near the Galactic Center

A group of four compact H II regions associated with the well-known 50 km/s molecular cloud is the closest site of on-going star formation to the dynamical center of the Galaxy, at a projected distance of approximately 6 pc. We present a study of ionized gas based on the [Ne II] (12.8 micron) line, as well as multi-frequency radio continuum, Hubble Space Telescope Pa alpha, and Spitzer Infrared Array Camera observations of the most compact member of the H II group, Sgr A East H II D. The radio continuum image at 6 cm shows that this source breaks up into two equally bright ionized features, D1 and D2. The spectral energy distribution of the D source is consistent with it being due to a 25 =/- 3 solar mass star with a luminosity of 8 +/- 3 x 10(exp 4) Solar luminosity . The inferred mass, effective temperature of the UV source, and the ionization rate are compatible with a young O9-B0 star. The ionized features D1 and D2 are considered to be ionized by UV radiation collimated by an accretion disk. We consider that the central massive star photoevaporates its circumstellar disk on a timescale of 3x (exp 4) years giving a mass flux approximately 3 x 10(exp -5) Solar Mass / year and producing the ionized material in D1 and D2 expanding in an inhomogeneous medium. The ionized gas kinematics, as traced by the [Ne II] emission, is difficult to interpret, but it could be explained by the interaction of a bipolar jet with surrounding gas along with what appears to be a conical wall of lower velocity gas. The other H II regions, Sgr A East A-C, have morphologies and kinematics that more closely resemble cometary flows seen in other compact H II regions, where gas moves along a paraboloidal surface formed by the interaction of a stellar wind with a molecular cloud.

Yusef-Zadeh, F.↗
NASA NTRS2011

Distributed Capacitive Sensor for Sample Mass Measurement

Previous robotic sample return missions lacked in situ sample verification/ quantity measurement instruments. Therefore, the outcome of the mission remained unclear until spacecraft return. In situ sample verification systems such as this Distributed Capacitive (DisC) sensor would enable an unmanned spacecraft system to re-attempt the sample acquisition procedures until the capture of desired sample quantity is positively confirmed, thereby maximizing the prospect for scientific reward. The DisC device contains a 10-cm-diameter pressure-sensitive elastic membrane placed at the bottom of a sample canister. The membrane deforms under the weight of accumulating planetary sample. The membrane is positioned in close proximity to an opposing rigid substrate with a narrow gap. The deformation of the membrane makes the gap narrower, resulting in increased capacitance between the two parallel plates (elastic membrane and rigid substrate). C-V conversion circuits on a nearby PCB (printed circuit board) provide capacitance readout via LVDS (low-voltage differential signaling) interface. The capacitance method was chosen over other potential approaches such as the piezoelectric method because of its inherent temperature stability advantage. A reference capacitor and temperature sensor are embedded in the system to compensate for temperature effects. The pressure-sensitive membranes are aluminum 6061, stainless steel (SUS) 403, and metal-coated polyimide plates. The thicknesses of these membranes range from 250 to 500 m. The rigid substrate is made with a 1- to 2-mm-thick wafer of one of the following materials depending on the application requirements glass, silicon, polyimide, PCB substrate. The glass substrate is fabricated by a microelectromechanical systems (MEMS) fabrication approach. Several concentric electrode patterns are printed on the substrate. The initial gap between the two plates, 100 m, is defined by a silicon spacer ring that is anodically bonded to the glass substrate. The fabricated proof-of-concept devices have successfully demonstrated tens to hundreds of picofarads of capacitance change when a simulated sample (100 g to 500 g) is placed on the membrane.

Toda, Risaku↗
NASA NTRS2011

First Detections of the [NII] 122 Micrometer Line at High Redshift: Demonstrating the Utility of the Line for Studying Galaxies in the Early Universe

We report the first detections of the [NIl] 122 {\mu} m line from a high redshift galaxy. The line was strongly (> 6{\sigma}) detected from SMMJ02399-0136, and HI413+ 117 (the Cloverleaf QSO) using the Redshift(z) and Early Universe Spectrometer (ZEUS) on the CSO. The lines from both sources are quite bright with line-to-FIR continuum luminosity ratios that are approx.7.0x10(exp -4) (Cloverleaf) and 2.1x10(exp -3) (SMMJ02399). With ratios 2-10 times larger than the average value for nearby galaxies, neither source exhibits the line-to-continuum deficits seen in nearby sources. The line strengths also indicate large ionized gas fractions, approx.8 to 17% of the molecular gas mass. The [OIII]/[NII] line ratio is very sensitive to the effective temperature of ionizing stars and the ionization parameter for emission arising in the narrow-line region (NLR) of an AGN. Using our previous detection of the [01II] 88 {\mu}m line, the [OIII]/ [NIl] line ratio for SMMJ02399-0136 indicates the dominant source of the line emission is either stellar HII regions ionized by 09.5 stars, or the NLR of the AGN with ionization parameter 10g(U) = -3.3 to -4.0. A composite system, where 30 to 50% of the FIR lines arise in the NLR also matches the data. The Cloverleaf is best modeled by a superposition of approx.200 M82like starbursts accounting for all of the FIR emission and 43% of the [NIl] line. The remainder may come from the NLR. This work demonstrates the utility of the [NIl] and [OIII] lines in constraining properties of the ionized medium.

Ferkinhoff, Carl↗
NASA NTRS2012

Reacting Multi-Species Gas Capability for USM3D Flow Solver

The USM3D Navier-Stokes flow solver contributed heavily to the NASA Constellation Project (CxP) as a highly productive computational tool for generating the aerodynamic databases for the Ares I and V launch vehicles and Orion launch abort vehicle (LAV). USM3D is currently limited to ideal-gas flows, which are not adequate for modeling the chemistry or temperature effects of hot-gas jet flows. This task was initiated to create an efficient implementation of multi-species gas and equilibrium chemistry into the USM3D code to improve its predictive capabilities for hot jet impingement effects. The goal of this NASA Engineering and Safety Center (NESC) assessment was to implement and validate a simulation capability to handle real-gas effects in the USM3D code. This document contains the outcome of the NESC assessment.

Frink, Neal T.↗
NASA NTRS2012

The Dust Properties of Hot R Coronae Borealis Stars and a Wolf-Rayet Central Star of a Planetary Nebula: In Search of the Missing Link

We present new Spitzer IIRS spectra of two hot R Coronae Borealis (RCB) stars, one in the Galaxy,V348 Sgr, and one lying in the Large Magellanic Cloud, HV 2671. These two objects constitute a link between the RCB stars and the [WCL] class of central stars of planetary nebula (CSPNe) that has little or no hydrogen in their atmospheres such as CPD -560 8032. HV 2671 and V348 Sgr are members of a rare subclass that has significantly higher effective temperatures than most RCB stars, but sharing the traits of hydrogen deficiency and dust formation that define the cooler RCB stars. The [WC] CSPNe star, CPD -560 8032, displays evidence for dual-dust chemistry showing both PAHs and crystalline silicates in its mid-IR spectrum. HV 2671 shows strong PAH emission but shows no sign of having crystalline silicates. The spectrum of V348 Sgr is very different from those of CPD -56deg 8032 and HV 2671. The PAH emission seen strongly in the other two stars is only weakly present. Instead, the spectrum is dominated by a broad emission centered at about 8.5 microns. This feature is not identified with either PAHs or silicates. Several other novae and post-asymptotic giant branch stars show similar features in their IR spectra. The mid-IR spectrum of CPD -56deg 8032 shows emission features associated with C60 . The other two stars do not show evidence for C60. The nature of the dust around these stars does not help us in establishing further links that may indicate a common origin.

Clayton, Geoffrey C.↗
NASA NTRS2011

First Detections of the [N II] 122 micron Line at High Redshift: Demonstrating the Utility of the Line for Studying Galaxies in the Early Universe

We report the first detections of the [N II] 122 micron line from a high-redshift galaxy. The line was strongly (>6(sigma)) detected from SMMJ02399-0136, and H1413 + 117 (the Cloverleaf QSO) using the Redshift (zeta) and Early Universe Spectrometer on the Caltech Submillimeter Observatory. The lines from both sources are quite bright with line to far-infrared (FIR) continuum luminosity ratios that are approx.7.0 x 10(exp -4) (Cloverleaf) and 2.1 x 10(exo -3) (SMMJ02399). With ratios 2-10 times larger than the average value for nearby galaxies, neither source exhibits the line to continuum deficits seen in nearby sources. The line strengths also indicate large ionized gas fractions, approx.8%-17% of the molecUlar gas mass. The [O III]/[N II] line ratio is very sensitive to the effective temperature of ionizing stars and the ionization parameter for emission arising in the narrow-line region (NLR) of an active galactic nucleus (AGN). Using Our previous detection of the [O III] 88 micron line, the [O III]/[N II]line ratio for SMMJ02399-0136 indicates that the dominant source of the line emission is either stellar H II regions ionized by O9.5 stars, or the NLR of the AGN with ionization parameter log(U) = -3.3 to -4.0. A composite system, where 30%-50% of the FIR lines arise in the NLR also matches the data. The Cloverleaf is best modeled by a superposition of approx.200 M82-like starbursts accounting for all of the FIR emission and 43% of the [N II]line. The remainder may come from the NLR. This war!< demonstrates the utility of the [N II] and [O III] lines in constraining properties of the ionized medium.

Ferkinhoff, Carl↗