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NASA NTRS2011

Search for Cosmic-Ray Antiproton Origins and for Cosmological Antimatter with BESS

The balloon-borne experiment with a superconducting spectrometer (BESS) has performed cosmic-ray observations as a US-Japan cooperative space science program, and has provided fundamental data on cosmic rays to study elementary particle phenomena in the early Universe. The BESS experiment has measured the energy spectra of cosmic-ray antiprotons to investigate signatures of possible exotic origins such as dark matter candidates or primordial black holes. and searched for heavier antinuclei that might reach Earth from antimatter domains formed in the early Universe. The apex of the BESS program was reached with the Antarctic flight of BESS-Polar II, during the 2007- 2008 Austral Summer, that obtained over 4.7 billion cosmic-ray events from 24.5 days of observation. The flight took place at the expected solar minimum, when the sensitivity of the low-energy antiproton measurements to a primary source is greatest. Here, we report the scientific restults, focusing on the long-duration flights of BESS-Polar I (2004) and BESS-Polar II (2007-2008).

Yamamoto, A.↗

NASA NTRS2012

X-Ray Emission from Supernovae in Dense Circumstellar Matter Environments: A Search for Collisionless Shock

The optical light curve of some supernovae (SNe) may be powered by the outward diffusion of the energy deposited by the explosion shock (so-called shock breakout) in optically thick (tau approx > 30) circumstellar matter (CSM). Recently, it was shown that the radiation-mediated and -dominated shock in an optically thick wind must transform into 8. collisionless shock and can produce hard X-rays. The X-rays are expected to peak at late times, relative to maximum visible light. Here we report on a search, using Swift-XRT and Chandra, for X-ray emission from 28 SNe that belong to classes whose progenitors are suspected to be embedded in dense CSM. Our sample includes 19 type-IIn SNe, one type-Ibn SN and ei~ht hydrogen-poor super-luminous SNe (SLSN-I; SN 2005ap like). Two SNe (SN 2006jc and SN 2010jl) have X-ray properties that are roughly consistent with the expectation for X-rays from a collisionless shock in optically thick CSl\l. Therefore, we suggest that their optical light curves are powered by shock breakout in CSM. We show that two other events (SN 2010al and SN 2011ht) were too X-ray bright during the SN maximum optical light to be explained by the shock breakout model. We conclude that the light curves of some, but not all, type-IIn/Ibn SNe are powered by shock breakout in CSM. For the rest of the SNe in our sample, including all the SLSN-I events, our X-ray limits are not deep enough and were typically obtained at too early times (i.e., near the SN maximum light) to conclude about their nature. Late time X-ray observations are required in order to further test if these SNe are indeed embedded in dense CSM. We review the conditions required for a shock breakOut in a wind profile. We argue that the time scale, relative to maximum light, for the SN to peak in X-rays is a probe of the column density and the density profile above the shock region. The optical light curves of SNe, for which the X-ray emission peaks at late times, are likely powered by the diffusion of shock energy from a dense CSM. We note that if the CSM density profile falls faster than a constant-rate wind density profile, then X-rays may escape at earlier times than estimated for the wind profile case. Furthermore, if the CSM have a region in which the density profile is very steep, relative to a steady wind density profile, or the CSM is neutral, then the radio free-free absorption may be low enough, and radio emission may be detected.

Ofek, E.O↗

NASA NTRS2012

The Early Universe: Searching for Evidence of Cosmic Inflation

In the past two decades, our understanding of the evolution and fate of the universe has increased dramatically. This "Age of Precision Cosmology" has been ushered in by measurements that have both elucidated the details of the Big Bang cosmology and set the direction for future lines of inquiry. Our universe appears to consist of 5% baryonic matter; 23% of the universe's energy content is dark matter which is responsible for the observed structure in the universe; and 72% of the energy density is so-called "dark energy" that is currently accelerating the expansion of the universe. In addition, our universe has been measured to be geometrically flat to 1 %. These observations and related details of the Big Bang paradigm have hinted that the universe underwent an epoch of accelerated expansion known as "inflation" early in its history. In this talk, I will review the highlights of modern cosmology, focusing on the contributions made by measurements of the cosmic microwave background, the faint afterglow of the Big Bang. I will also describe new instruments designed to measure the polarization of the cosmic microwave background in order to search for evidence of cosmic inflation.

Chuss, David T.↗

NASA NTRS2011

Search for Gravitational Waves Associated with the August 2006 Timing Glitch of the Vela Pulsar

The physical mechanisms responsible for pulsar timing glitches are thought to excite quasinormal mode oscillations in their parent neutron star that couple to gravitational-wave emission, In August 2006, a timing glitch was observed in the radio emission of PSR B0833-45, the Vela pulsar. At the time of the glitch, the two colocated Hanford gravitational-wave detectors of the Laser Interferometer Gravitational-wave observatory (LIGO) were operational and taking data as part of the fifth LIGO science run (S5). We present the first direct search for the gravitational-wave emission associated with oscillations of the fundamental quadrupole mode excited by a pulsar timing glitch. No gravitational-wave detection candidate was found. We place Bayesian 90% confidence upper limits of 6,3 x 10(exp -21) to 1.4 x 10(exp -20) on the peak: intrinsic strain amplitude of gravitational-wave ring-down signals, depending on which spherical harmonic mode is excited. The corresponding range of energy upper limits is 5.0 x 10(exp 44) to 1.3 x 10(exp 45) erg.

Camp, J. B.↗

NASA NTRS2012

Search for X-Ray Emission Associated with the Shapley Supercluster with Suzaku

Suzaku performed observations of 3 regions in and around the Shapley supercluster: a region located between A3558 and A3556, at approx 0.9 times the virial radii of both clusters, and two other regions at 1 deg and 4 away from the first pointing. The 4 deg -otfset observation was used to evaluate the Galactic foreground emission. We did not detect significant redshifted Oxygen emission lines (O VII and O VIII) in the spectra of all three pointings, after subtracting the contribution of foreground and background emission. An upper limit for the redshifted O VIII Ka line intensity of the warm-hot intergalactic medium (WHIM) is 1.5 x 10(exp -7) photons / s / sq cm / sq arcmin, which corresponds to an overdensity of approx 380 (Z/0.1 Solar Z)(exp -1/2)(L/3 Mpc)(exp -1/2), assuming T = 3 x 10(exp 6) K. We found excess continuum emission in the 1 deg-offset and on-filament regions, represented by thermal models with kT approximates 1 keV and approximates 2 keV, respectively. The redshifts of both 0 and that of the supercluster (0.048) are consistent with the observed spectra. The approx 1 keV emission can be also fitted with Ne-rich Galactic (zero redshift) thin thermal emission. Radial intensity profile of 2 keV component suggests contribution from A3558 and A3556, but with significant steepening of the intensity slope in the outer region of A3558. Finally, we summarized the previous Suzaku search for the WHIM and discussed the feasibility of constraining the WHIM. An overdensity of <400 can be detectable using O VII and O VIII emission lines in a range of 1.4 x 10(exp 6) K < T < 5 x 10(exp 6) K or a continuum emission in a relatively high temperature range T > 5 x 10 (exp 6) K with the Suzaku XIS. The non detection with Suzaku suggests that typical line-of-sight average overdensity is < 400.

Mitsuishi, Ikuyuki↗

NASA NTRS2012

The Role of (Delta)C-13 in the Search for Reduced Organics on the Surface of Mars

The capabilities of the Sample Analysis at Mars (SAM) instrument suite on the Mars Science Laboratory (MSL) to detect trace amounts of organic carbon compounds are unprecedented, and MSL may be the first mission to reveal the presence of organic carbon on Mars. The search for reduced organic carbon on Mars is inextricably tied to: a) the preservation potential of the environment from which we take a solid sample, and b) the evolved gas analysis (EGA) techniques used by SAM to release volatiles from this solid sample. Several prospective targets have been identified for sample analysis at Gale Crater. Stratigraphic sequences of phyllosilicates and sulfates at Gale are thought to represent a period of global climate transition from a moderate pH lacustrine environment to an evaporitic environment, both of which could sequester organic carbon (Thomson et al. 2011). The sediment mound in Gale Crater contains a range of lithologies suggesting changes in redox conditions, and evidence of both lacustrine and fluvial depositional processes, which may have transported organic carbon from the layer in which it formed and resulted in its preservation elsewhere within the crater (Anderson and Bell, 2010). Inverted channel fills suggest erosion resistant material that could serve to preserve organics originally deposited in a low energy aqueous environment. The lithology sampled will affect not only the preservation of organics, but also our ability to detect organics during our evolved gas analysis, based on the sample matrix. For example, reduced organics may be trapped in the mineral structure, and thermal evolution of these organics will occur during thermal decomposition of the host mineral. If organics are occluded in minerals that have very high thermal decomposition temperatures, they may be, in effect, "too well preserved," and difficult to detect during EGA. Alternatively, the possible presence of perchlorate, or other strong oxidants in surface regolith, may result in destruction of structural information identifying organic molecules before reaching the QMS on SAM via oxidation to C02 during heating. If this is the case, the stable carbon isotopic composition (delta 13C) of the C02 evolved and measured by the Tunable Laser Spectrometer (TLS) on SAM may help identify the presence of organics. On Earth, biological activity can cause large fractionations of 13C/12C, which can preserved in sedimentary deposits and distinguish the organic products of biotic processes from inorganic atmospheric and geological reservoirs. It is plausible that similar fractionations could occur on Mars and be preserved in reduced organic matter in sediments. Bulk delta 13C measurements alone may not reveal a signature of trace organic carbon that may be present along with inorganic carbon. If both organic and inorganic carbon compounds are present, it may be possible to detect the organic carbon by comparing the 013C of pyrolysis and combustion experiments. The TLS on SAM is capable of obtaining high precision measurements of delta13C from C02 evolved during pyrolysis and combustion of solid regolith samples. Because carbonates are expected to be present at abundances of 0.1-1 % in Martian soil, and organics in the ppb range (Webster and Mahaffy, 2011), analog samples must represent this mix of reduced organic carbon and carbonate. The work presented here will examine the use of delta13C of C02 produced during combustion of bulk Mars analog samples as a proxy for detection of reduced organic carbon.

Stern, J. C.↗

NASA NTRS2012

The Search for Nonflammable Solvent Alternatives for Cleaning Aerospace Oxygen Systems

To obtain a high degree of cleanliness without risk of corrosion or hazardous reactivity, hydrochlorofluorocarbon (HCFC)-225 is used for cleaning and cleanliness verification of oxygen system components used on NASA fs bipropellant launch vehicles, associated test stands and support equipment. HCFC-225 is a Class II Ozone Depleting Substance (ODS ]II) that was introduced to replace chlorofluorocarbon (CFC)-113, a Class I ODS solvent that is now banned. To meet environmental regulations to eliminate the use of ozone depleting substances, a replacement solvent is required for HCFC ]225 that is effective at removing oils, greases, and particulate from large oxygen system components, is compatible with materials used in the construction of these systems, and is nonflammable and non ]reactive in enriched oxygen environments. A solvent replacement is also required for aviator fs breathing oxygen systems and other related equipment currently cleaned and verified with HCFC ]225 and stockpiled CFC -113. Requirements and challenges in the search for nonflammable replacement solvents are discussed.

Mitchell, Mark A.↗

NASA NTRS2012

The Search for Nonflammable Solvent Alternatives for Cleaning Aerospace Oxygen Systems

Oxygen systems are susceptible to fires caused by particle and nonvolatile residue (NVR) contaminants, therefore cleaning and verification is essential for system safety. . Cleaning solvents used on oxygen system components must be either nonflammable in pure oxygen or complete removal must be assured for system safety. . CFC -113 was the solvent of choice before 1996 because it was effective, least toxic, compatible with most materials of construction, and non ]reactive with oxygen. When CFC -113 was phased out in 1996, HCFC -225 was selected as an interim replacement for cleaning propulsion oxygen systems at NASA. HCFC-225 production phase-out date is 01/01/2015. HCFC ]225 (AK ]225G) is used extensively at Marshall Space Flight Center and Stennis Space Center for cleaning and NVR verification on large propulsion oxygen systems, and propulsion test stands and ground support equipment. . Many components are too large for ultrasonic agitation - necessary for effective aqueous cleaning and NVR sampling. . Test stand equipment must be cleaned prior to installation of test hardware. Many items must be cleaned by wipe or flush in situ where complete removal of a flammable solvent cannot be assured. The search for a replacement solvent for these applications is ongoing.

Mitchell, Mark↗

NASA NTRS2013

Radio Detection of the Fermi-LAT Blind Search Millisecond Pulsar J1311-3430

We report the detection of radio emission from PSR J1311.3430, the first millisecond pulsar (MSP) discovered in a blind search of Fermi Large Area Telescope (LAT) gamma-ray data. We detected radio pulsations at 2 GHz, visible for less than 10% of approximately 4.5 hr of observations using the Green Bank Telescope (GBT). Observations at 5 GHz with the GBT and at several lower frequencies with Parkes, Nan cay, and the Giant Metrewave Radio Telescope resulted in non-detections. We also report the faint detection of a steep spectrum continuum radio source (0.1 mJy at 5 GHz) in interferometric imaging observations with the Jansky Very Large Array. These detections demonstrate that PSR J1311.3430 is not radio quiet and provide additional evidence that radio-quiet MSPs are rare. The radio dispersion measure of 37.8 pc cm(exp -3) provides a distance estimate of 1.4 kpc for the system, yielding a gamma-ray efficiency of 30%, typical of LAT-detected MSPs. We see apparent excess delay in the radio pulses as the pulsar appears from eclipse and we speculate on possible mechanisms for the non-detections of the pulse at other orbital phases and observing frequencies.

Ray, P. S.↗

NASA NTRS2013

Moduli Dark Matter and the Search for Its Decay Line using Suzaku X-Ray Telescope

Light scalar fields called moduli arise from a variety of different models involving supersymmetry and/or string theory; thus their existence is a generic prediction of leading theories for physics beyond the standard model. They also present a formidable, long-standing problem for cosmology. We argue that an anthropic solution to the moduli problem exists in the case of small moduli masses and that it automatically leads to dark matter in the form of moduli. The recent discovery of the 125 GeV Higgs boson implies a lower bound on the moduli mass of about a keV. This form of dark matter is consistent with the observed properties of structure formation, and it is amenable to detection with the help of x-ray telescopes. We present the results of a search for such dark matter particles using spectra extracted from the first deep x-ray observations of the Draco and Ursa Minor dwarf spheroidal galaxies, which are darkmatter- dominated systems with extreme mass-to-light ratios and low intrinsic backgrounds. No emission line is positively detected, and we set new constraints on the relevant new physics.

Kusenko, Alexander↗

NASA NTRS2013

The Antarctic Search for Meteorites: A Model for Deep Space Exploration

In an era of shrinking buying power and reduced flight opportunities, NASA must extract the greatest possible value from all sources of insight into the future of human space exploration. Antarctica is one such source. The history of Antarctic exploration has many political and technical parallels with the development of space, and Antarctica's remoteness and harsh climate make it an excellent proxy for space (e.g., [1,2]). Links between exploration of space and of the Antarctic date back to the International Geophysical Year of 1957-1958, which saw both the launch of Sputnik 1 and the establishment of a station at the South Pole. The Antarctic Search for Meteorites (ANSMET) is an annual expedition to the south polar plateau to collect meteorites. Although its intent is not to simulate a space mission, the handful of astronauts who have participated in ANSMET agree that it is very similar to a long-duration space flight. Independently, NASA and other space agencies have simulated deep space exploration missions in "analog" activities at remote field sites on Earth (e.g., [3]). These include NASA Extreme Environment Mission Operations (NEEMO) [4,5], Desert Research And Technology Studies (Desert RATS) [6,7], and the Pavilion Lake Research Project (PLRP or simply Pavilion Lake) [8]. This report focuses on NEEMO, Desert RATS, and PLRP because of the author's firsthand experience with them. Other noteworthy analogs, such as the arctic Haughton Mars Project and the European Space Agency's underground Cooperative Adventure for Valuing and Exercising human behavior and performance Skills (CAVES), are not treated here. NASA analogs often include fully staffed control centers, astronauts serving as crew, and realistic mission timelines lasting one to two weeks. Analogs have provided key insights into system architectures and operational concepts for the future human exploration of deep space. They have pioneered techniques for human communication with significant speed-of-light delays, for conducting spacewalks on natural objects with negligible surface gravity, and for empowering exploration crews to work with reduced dependence on a ground control center. They have field-tested dozens of emerging technologies including spacewalking tools and full-scale prototype vehicles and habitats. They have provided valuable experience for astronauts preparing for their first space flight, and for flown crewmembers who will take command roles on later flights. Some analogs, especially PLRP, have connected observers in the field with science teams in remotely located control centers to produce high-quality, publishable scientific results. The analogs have accomplished all of this at a tiny fraction of the cost of an actual space flight. This report treats ANSMET as space flight analog. The chapter following this introduction describes ANSMET in depth. The report then presents data on logistics and crew considerations that may be useful for developers of future human space exploration missions. It offers detailed comparisons between ANSMET and past, present, and future space flights on the Space Shuttle, the International Space Station (ISS), and a proposed Mars mission. Those comparisons are intended to complement the work of Eppler [2], who compares ANSMET to the Apollo moon flights. This report also compares ANSMET with the Desert RATS, NEEMO, and PLRP analogs. It then presents observations and makes recommendations related to ANSMET's value as a simulated space mission. The report ends with a short conclusion. The remainder of this introductory chapter provides background material to help readers interpret the rest of the report. It gives brief overviews of Space Shuttle and ISS missions along with information on a notional future human flight to Mars. It also presents the general features of three of NASA's space flight "analog" projects. With those points of reference in place, the chapter concludes with an overview of ANSMET.

Love, Stanley G.↗

NASA NTRS2013

The Search for Nitrates on Mars by the Sample Analysis at Mars (SAM) Instrument

Planetary models suggest that nitrogen was abundant in the early Martian atmosphere as N2 but it was lost by sputtering and photochemical loss to space, impact erosion, and chemical oxidation to nitrates. A nitrogen cycle may exist on Mars where nitrates, produced early in Mars' history, may have been later decomposed back into N2 by the current impact flux. Nitrates are a fundamental source of nitrogen for terrestrial microorganisms, and they have evolved metabolic pathways to perform both oxidation and reduction to drive a complete biological nitrogen cycle. Therefore, the characterization of nitrogen in Martian soils is important to assess habitability of the Martian environment, particularly with respect to the presence of nitrates. The only previous mission that was designed to search for soil nitrates was the Phoenix mission but N-containing species were not detected by TEGA or the MECA WCL. Nitrates have been tentatively identified in Nakhla meteorites, and if nitrogen was oxidized on Mars, this has important implications for the habitability potential of Mars. Here we report the results from the Sample Analysis at Mars (SAM) instrument suite aboard the Curiosity rover during the first year of surface operations in Gale Crater. Samples from the Rocknest aeolian deposit and sedimentary rocks (John Klein) were heated to approx 835degC under helium flow and the evolved gases were analyzed by MS and GC-MS. Two and possibly three peaks may be associated with the release of m/z 30 at temperatures ranging from 180degC to 500degC. M/z 30 has been tentatively identified as NO; other plausible contributions include CH2O and an isotopologue of CO, 12C18O. NO, CH2O, and CO may be reaction products of reagents (MTBSTFA/DMF) carried from Earth for the wet chemical derivatization experiments with SAM and/or derived from indigenous soil nitrogenated organics. Laboratory analyses indicate that it is also possible that <550degC evolved NO is produced via reaction of HCl with nitrates arising from the decomposition of perchlorates. All sources of m/z 30 whether it be martian or terrestrial will be considered and their implications for Mars will be discussed.

Navarro-Gonzalez, Rafael↗

NASA NTRS2014

Searching for Reduced Carbon on the Surface of Mars: The SAM Combustion Experiment

The search for reduced carbon has been a major focus of past and present missions to Mars. Thermal evolved gas analysis was used by the Viking and Phoenix landers and is currently in use by the Sample Analysis at Mars (SAM) instrument suite on the Mars Science Laboratory (MSL) to characterize volatiles evolved from solid samples, including those associated with reduced organic species. SAM has the additional capability to perform a combustion experiment, in which a sample of Mars regolith is heated in the presence of oxygen and the composition of the evolved gases is measured using quadrupole mass spectrometry (QMS) and tunable laser spectrometry (TLS) [1]. Organics detection on the Martian surface has been complicated by oxidation and destruction during heating by soil oxidants [2], including oxychlorine compounds, and terrestrial organics in the SAM background contributed by one of the SAM wet chemistry reagents MTBSTFA (N-Methyl-N-tertbutyldimethylsilyl- trifluoroacetamide) [3,4]. Thermal Evolved Gas Analysis (TEGA) results from Phoenix show a mid temperature CO2 release between 400 C - 680 C speculated to be carbonate, CO2 adsorbed to grains, or combustion of organics by soil oxidants [5]. Low temperature CO2 evolutions (approx. 200 C - 400 C) were also present at all three sites in Gale Crater where SAM Evolved Gas Analysis (EGA) was performed, and potential sources include combustion of terrestrial organics from SAM, as well as combustion and/or decarboxylation either indigenous martian or exogenous organic carbon [4,6]. By performing an experiment to intentionally combust all reduced materials in the sample, we hope to compare the bulk abundance of CO2 and other oxidized species evolved by combustion to that evolved during an EGA experiment to estimate how much CO2 could be contributed by reduced carbon sources. In addition, C, O, and H isotopic compositions of CO2 and H2O measured by TLS can contribute information regarding the potential sources of these volatiles.

Stern, J. C.↗

NASA NTRS2014

Search for Fluid Inclusions in a Carbonaceous Chondrite Using a New X-Ray Micro-Tomography Technique Combined with FIB Sampling

Early solar system aqueous fluids are preserved in some H chondrites as aqueous fluid inclusions in halite (e.g., [1]). Although potential fluid inclusions are also expected in carbonaceous chondrites [2], they have not been surely confirmed. In order to search for these fluid inclusions, we have developped a new X-ray micro-tomography technique combined with FIB sampling and applied this techniqu to a carbanaceous chondrite. Experimental: A polished thin section of Sutter's Mill meteorite (CM) was observed with an optical microscope and FE-SEM (JEOL 7001F) for chosing mineral grains of carbonates (mainly calcite) and sulfides (FeS and ZnS) 20-50 microns in typical size, which may have aqueous fluid inclusions. Then, a "house" similar to a cube with a roof (20-30 microns in size) is sampled from the mineral grain by using FIB (FEI Quanta 200 3DS). Then, the house was atached to a thin W-needle by FIB and imaged by a SR-based imaging microtomography system with a Fresnel zone plate at beamline BL47XU, SPring-8, Japan. One sample was imaged at two X-ray energies, 7 and 8 keV, to identify mineral phases (dual-enegy microtomography: [3]). The size of voxel (pixel in 3D) was 50-80 nm, which gave the effective spatial resolution of approx. 200 nm. A terrestrial quartz sample with an aqueous fluid inclusion with a bubble was also examined as a test sample by the same method. Results and discussion: A fluid inclusion of 5-8 microns in quartz was clearly identified in a CT image. A bubble of approx. 4 microns was also identified as refraction contrast although the X-ray absorption difference between fluid and bubble is small. Volumes of the fluid and bubble were obtained from the 3D CT images. Fourteen grains of calcite, two grains of iron sulfide and one grain of (Zn,Fe)S were examined. Ten calcite, one iron sulfide and one (Zn,Fe)S grains have inclusions >1 micron in size (the maximum: approx. 5 microns). The shapes are spherical or irregular. Tiny inclusions (<1 micron) are also present in all the grains examined. These results show that mineral grains have more inclusions than expected from 2D observations. The X-ray absorption of the inclusions shows that they are not solid inclusions. No bubbles were observed inside, indicating that we cannot determine whether they are really aqueous fluids or merely voids. One calcite grain has an inclusion approx. 2 microns in size, which seems to have a bubble and a tiny solid daughter crystal inside (three-phase inclusion). As we know the exact 3D position of the inclusion, we will anlyze the inclusion by SIMS after freezing the sample as has been done for a halite sample [3]. The present technique is useful for finding small inclusions not only in carbonaceous chondrites but also for terrestrial materials.

Tsuchiyama, A.↗

NASA NTRS2014

First Searches for Optical Counterparts to Gravitational-Wave Candidate Events

During the Laser Interferometer Gravitational-wave Observatory and Virgo joint science runs in 2009-2010, gravitational wave (GW) data from three interferometer detectors were analyzed within minutes to select GW candidate events and infer their apparent sky positions. Target coordinates were transmitted to several telescopes for follow-up observations aimed at the detection of an associated optical transient. Images were obtained for eight such GW candidates. We present the methods used to analyze the image data as well as the transient search results. No optical transient was identified with a convincing association with any of these candidates, and none of the GW triggers showed strong evidence for being astrophysical in nature. We compare the sensitivities of these observations to several model light curves from possible sources of interest, and discuss prospects for future joint GW-optical observations of this type.

gravitational waves↗

NASA NTRS2013

The Antarctic Search for Meteorites: The Future of Space, on Earth Today - EVA Knowledge Capture Outbrief

NASA astronaut Stan Love shared his experiences with the Antarctic Search for Meteorites (ANSMET), an annual expedition to the southern continent to collect valuable samples for research in planetary science. ANSMET teams operate from isolated, remote field camps on the polar plateau, where windchill factors often reach -40 F. Several astronaut participants have noted ANSMET's similarity to a space mission. Some of the operational concepts, tools, and equipment employed by ANSMET teams may offer valuable insights to designers of future planetary surface exploration hardware.

Love, Stan↗

NASA NTRS2013

On the Nature of the mHz X-ray Quasi-Periodic Oscillations from Ultraluminous X-ray source M82 X−1: Search for Timing-Spectral Correlations

Using all the archival XMM-Newton X-ray (3-10 keV) observations of the ultraluminous X-ray source (ULX) M82 X−1, we searched for a correlation between its variable mHz quasi-periodic oscillation (QPO) frequency and its hardness ratio (5-10 keV/3-5 keV), an indicator of the energy spectral power-law index. When stellar-mass black holes (StMBHs) exhibit type-C low-frequency QPOs (∼0.2-15 Hz), the centroid frequency of the QPO is known to correlate with the energy spectral index. The detection of such a correlation would strengthen the identification of M82 X−1's mHz QPOs as type-C and enable a more reliable mass estimate by scaling its QPO frequencies to those of type-C QPOs in StMBHs of known mass.We resolved the count rates and the hardness ratios of M82 X−1 and a nearby bright ULX (source 5/X42.3+59) through surface brightness modeling.We detected QPOs in the frequency range of 36-210 mHz during which M82 X−1's hardness ratio varied from 0.42 to 0.47. Our primary results are (1) that we do not detect any correlation between the mHz QPO frequency and the hardness ratio (a substitute for the energy spectral power-law index) and (2) similar to some accreting X-ray binaries, we find that M82 X−1's mHz QPO frequency increases with its X-ray count rate (Pearson's correlation coefficient = +0.97). The apparent lack of a correlation between the QPO centroid frequency and the hardness ratio poses a challenge to the earlier claims that the mHz QPOs of M82 X−1 are the analogs of the type-C low-frequency QPOs of StMBHs. On the other hand, it is possible that the observed relation between the hardness ratio and the QPO frequency represents the saturated portion of the correlation seen in type-C QPOs of StMBHs-in which case M82 X−1's mHz QPOs can still be analogous to type-C QPOs.

Nature↗

NASA NTRS2013

X-ray Emission from Supernovae in Dense Circumstellar Matter Environments: a Search for Collisionless Shocks

The optical light curve of some supernovae (SNe) may be powered by the outward diffusion of the energy deposited by the explosion shock (the so-called shock breakout) in optically thick (Tau approx > 30) circumstellar matter (CSM). Recently, it was shown that the radiation-mediated and radiation-dominated shock in an optically thick wind must transform into a collisionless shock and can produce hard X-rays. The X-rays are expected to peak at late times, relative to maximum visible light. Here we report on a search, using Swift/XRT and Chandra, for X-ray emission from 28 SNe that belong to classes whose progenitors are suspected to be embedded in dense CSM. Our sample includes 19 Type IIn SNe, one Type Ibn SN, and eight hydrogen-poor superluminous SNe (SLSN-I such as SN 2005ap). Two SNe (SN 2006jc and SN 2010jl) have X-ray properties that are roughly consistent with the expectation for X-rays from a collisionless shock in optically thick CSM. However, the X-ray emission from SN 2006jc can also be explained as originating in an optically thin region. Thus, we propose that the optical light curve of SN 2010jl is powered by shock breakout in CSM. We suggest that two other events (SN 2010al and SN 2011ht) were too X-ray bright during the SN maximum optical light to be explained by the shock-breakout model.We conclude that the light curves of some, but not all, SNe IIn/Ibn are powered by shock breakout in CSM. For the rest of the SNe in our sample, including all of the SLSN-I events, our X-ray limits are not deep enough and were typically obtained too early (i.e., near the SN maximum light) for definitive conclusions about their nature. Late-time X-ray observations are required in order to further test whether these SNe are indeed embedded in dense CSM. We review the conditions required for a shock breakout in a wind profile. We argue that the timescale, relative to maximum light, for the SN to peak in X-rays is a probe of the column density and the density profile above the shock region. In SNe whose X-ray emission slowly rises, and peaks at late times, the optical light curve is likely powered by the diffusion of shock energy in a dense CSM. We note that if the CSM density profile falls faster than a constant-rate wind-density profile, then X-rays may escape at earlier times than estimated for the wind-profile case. Furthermore, if the CSM has a region in which the density profile is very steep relative to a steady wind-density profile, or if the CSM is neutral, then the radio free-free absorption may be sufficiently low for radio emission to be detected.

matter↗