The interstellar medium in Andromeda's dwarf spheroidal galaxies - I. Content and origin of the interstellar dust

Dwarf spheroidal galaxies are among the most numerous galaxy population in the Universe, but their main formation and evolution channels are still not well understood. The three dwarf spheroidal satellites (NGC147, NGC185, and NGC205) of the Andromeda galaxy are characterised by very different interstellar medium (ISM) properties, which might suggest them being at different galaxy evolutionary stages. While the dust content of NGC205 has been studied in detail by De Looze et al. (2012), we present new Herschel dust continuum observations of NGC147 and NGC185. The non-detection of NGC147 in Herschel SPIRE maps puts a strong constraint on its dust mass (< 128 Msun). For NGC185, we derive a total dust mass M_d = 5.1 x 10^3 Msun, which is a factor of ~2-3 higher than that derived from ISO and Spitzer observations and confirms the need for longer wavelength observations to trace more massive cold dust reservoirs. We, furthermore, estimate the dust production by asymptotic giant branch (AGB) stars and supernovae (SNe). For NGC147, the upper limit on the dust mass is consistent with expectations of the material injected by the evolved stellar population. In NGC185 and NGC205, the observed dust content is one order of magnitude higher compared to the estimated dust production by AGBs and SNe. Efficient grain growth, and potentially longer dust survival times (3-6 Gyr) are required to account for their current dust content. Our study confirms the importance of grain growth in the gas phase to account for the current dust reservoir in galaxies.DL gratefully acknowledge the support of the Science and Technology Facilities Council (STFC) and the Flemish Fund for Scientific Research (FWO-Vlaanderen). PACS has been developed by a consortium of institutes led by MPE (Germany) and including UVIE (Austria); KU Leuven, CSL, IMEC (Belgium); CEA, LAM (France); MPIA (Germany); INAFIFSI/OAA/OAP/OAT, LENS, SISSA (Italy); IAC (Spain). This development has been supported by the funding agencies BMVIT (Austria), ESA-PRODEX (Belgium), CEA/CNES (France), DLR (Germany), ASI/INAF (Italy), and CICYT/MCYT (Spain). SPIRE has been developed by a consortium of institutes led by Cardiff University (UK) and including Univ. Lethbridge (Canada); NAOC (China); CEA, LAM (France); IFSI, Univ. Padua (Italy); IAC (Spain); Stockholm Observatory (Sweden); Imperial College London, RAL, UCL-MSSL, UKATC, Univ. Sussex (UK); and Caltech, JPL, NHSC, Univ. Colorado (USA). This development has been supported by national funding agencies: CSA (Canada); NAOC (China); CEA, CNES, CNRS (France); ASI (Italy); MCINN (Spain); SNSB (Sweden); STFC and UKSA (UK); and NASA (USA). This research has made use of the NASA/IPAC Extragalactic Database (NED) which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.This is the author accepted manuscript. The final version is available from Oxford University Press via http://dx.doi.org/10.1093/mnras/stw86

The Herschel Exploitation of Local Galaxy Andromeda (HELGA) II: Dust and Gas in Andromeda

We present an analysis of the dust and gas in Andromeda, using Herschel images sampling the entire far-infrared peak. We fit a modified-blackbody model to ~4000 quasi-independent pixels with spatial resolution of ~140pc and find that a variable dust-emissivity index (beta) is required to fit the data. We find no significant long-wavelength excess above this model suggesting there is no cold dust component. We show that the gas-to-dust ratio varies radially, increasing from ~20 in the center to ~70 in the star-forming ring at 10kpc, consistent with the metallicity gradient. In the 10kpc ring the average beta is ~1.9, in good agreement with values determined for the Milky Way (MW). However, in contrast to the MW, we find significant radial variations in beta, which increases from 1.9 at 10kpc to ~2.5 at a radius of 3.1kpc and then decreases to 1.7 in the center. The dust temperature is fairly constant in the 10kpc ring (ranging from 17-20K), but increases strongly in the bulge to ~30K. Within 3.1kpc we find the dust temperature is highly correlated with the 3.6 micron flux, suggesting the general stellar population in the bulge is the dominant source of dust heating there. At larger radii, there is a weak correlation between the star formation rate and dust temperature. We find no evidence for 'dark gas' in M31 in contrast to recent results for the MW. Finally, we obtained an estimate of the CO X-factor by minimising the dispersion in the gas-to-dust ratio, obtaining a value of (1.9+/-0.4)x10^20 cm^-2 [K kms^-1]^-1.Comment: 19 pages, 18 figures. Submitted to ApJ April 2012; Accepted July 201

Coordinated Ionospheric Reconstruction CubeSat Experiment (CIRCE) mission overview

The Coordinated Ionospheric Reconstruction Cubesat Experiment (CIRCE) is a joint US/UK mission consisting of two 6U CubeSats actively maintaining a lead-follow configuration in the same low Earth orbit with a launch planned for the 2020 timeframe. These nanosatellites will each feature multiple space weather payloads. From the US, the Naval Research Laboratory will provide two 1U Triple Tiny Ionospheric Photometers (Tri-TIPs) on each satellite, observing the ultraviolet 135.6 nm emission of atomic oxygen at nighttime. The primary objective is to characterize the twodimensional distribution of electrons in the Equatorial Ionization Anomaly (EIA). The methodology used to reconstruct the nighttime ionosphere employs continuous UV photometry from four distinct viewing angles in combination with an additional data source, such as in situ plasma density measurements, with advanced image space reconstruction algorithm tomography techniques. From the UK, the Defence Science and Technology Laboratory (Dstl) is providing the In-situ and Remote Ionospheric Sensing suite consisting of an Ion/Neutral Mass Spectrometer, a triple-frequency GPS receiver for ionospheric sensing, and a radiation environment monitor. We present our mission concept, simulations illustrating the imaging capability of the Tri-TIP sensor suite, and a range of science questions addressable via these measurements

Ram pressure feeding super-massive black holes

When supermassive black holes at the center of galaxies accrete matter (usually gas), they give rise to highly energetic phenomena named Active Galactic Nuclei (AGN). A number of physical processes have been proposed to account for the funneling of gas towards the galaxy centers to feed the AGN. There are also several physical processes that can strip gas from a galaxy, and one of them is ram pressure stripping in galaxy clusters due to the hot and dense gas filling the space between galaxies. We report the discovery of a strong connection between severe ram pressure stripping and the presence of AGN activity. Searching in galaxy clusters at low redshift, we have selected the most extreme examples of jellyfish galaxies, which are galaxies with long tentacles of material extending for dozens of kpc beyond the galaxy disk. Using the MUSE spectrograph on the ESO Very Large Telescope, we find that 6 out of the 7 galaxies of this sample host a central AGN, and two of them also have galactic-scale AGN ionization cones. The high incidence of AGN among the most striking jellyfishes may be due to ram pressure causing gas to flow towards the center and triggering the AGN activity, or to an enhancement of the stripping caused by AGN energy injection, or both. Our analysis of the galaxy position and velocity relative to the cluster strongly supports the first hypothesis, and puts forward ram pressure as another, yet unforeseen, possible mechanism for feeding the central supermassive black hole with gas.Comment: published in Nature, Vol.548, Number 7667, pag.30

An assessment of monitoring requirements and costs of 'Reduced Emissions from Deforestation and Degradation'

<p>Abstract</p> <p>Background</p> <p>Negotiations on a future climate policy framework addressing Reduced Emissions from Deforestation and Degradation (REDD) are ongoing. Regardless of how such a framework will be designed, many technical solutions of estimating forest cover and forest carbon stock change exist to support policy in monitoring and accounting. These technologies typically combine remotely sensed data with ground-based inventories. In this article we assess the costs of monitoring REDD based on available technologies and requirements associated with key elements of REDD policy.</p> <p>Results</p> <p>We find that the design of a REDD policy framework (and specifically its rules) can have a significant impact on monitoring costs. Costs may vary from 0.5 to 550 US$ per square kilometre depending on the required precision of carbon stock and area change detection. Moreover, they follow economies of scale, i.e. single country or project solutions will face relatively higher monitoring costs.</p> <p>Conclusion</p> <p>Although monitoring costs are relatively small compared to other cost items within a REDD system, they should be shared not only among countries but also among sectors, because an integrated monitoring system would have multiple benefits for non-REDD management. Overcoming initialization costs and unequal access to monitoring technologies is crucial for implementation of an integrated monitoring system, and demands for international cooperation.</p

Major combined electrolyte deficiency during therapy with low-dose Cisplatin, 5-Fluorouracil and Interferon alpha: report on several cases and review of the literature [ISRCTN62866759]

BACKGROUND: Low-dose Cisplatin and Interferon alpha treatment of solid tumors rarely has been associated with severe hypocalcaemia. To the authors knowledge the phenomenon has not been reported previously in patients with pancreatic carcinoma. CASE PRESENTATION: A patient with resected adenocarcinoma of the pancreas was treated with adjuvant radio-chemo-immunotherapy using a combination of low-dose Cisplatin, 5-Fluorouracil and Interferon alpha together with external beam radiation. Severe hypocalcaemia without signs of acute renal failure or electrolyte disturbance occurred within 2 days at the 4th week of treatment and required intensive care treatment. CONCLUSION: Combination of biological and cytotoxic therapies may increase the incidence of severe hypocalcaemia in pancreatic cancer. Oncologists should remain attentive of this problem as more highly active regimes become available

The interstellar medium in Andromeda's dwarf spheroidal galaxies: II. Multi-phase gas content and ISM conditions

We make an inventory of the interstellar medium material in three low-metallicity dwarf spheroidal galaxies of the Local Group (NGC147, NGC185 and NGC205). Ancillary Hi, CO, \textit{Spitzer} IRS spectra, H$\alpha$ and X-ray observations are combined to trace the atomic, cold and warm molecular, ionised and hot gas phases. We present new Nobeyama CO(1-0) observations and \textit{Herschel} SPIRE FTS [Ci] observations of NGC205 to revise its molecular gas content. We derive total gas masses of Mg = 1.9-5.5x10$^5$ M$\odot$ for NGC185 and Mg = 8.6-25.0x10^5 M$\odot$ for NGC205. Non-detections combine to an upper limit on the gas mass of Mg =< 0.3-2.2x10^5 M$\odot$ for NGC147. The observed gas reservoirs are significantly lower compared to the expected gas masses based on a simple closed-box model that accounts for the gas mass returned by planetary nebulae and supernovae. The gas-to-dust mass ratios GDR~37-107 and GDR~48-139 are also considerably lower compared to the expected GDR~370 and GDR~520 for the low metal abundances in NGC 185 (0.36 Z$\odot$) and NGC205 (0.25 Z$\odot$), respectively. To simultaneously account for the gas deficiency and low gas-to-dust ratios, we require an efficient removal of a large gas fraction and a longer dust survival time (~1.6 Gyr). We believe that efficient galactic winds (combined with heating of gas to sufficiently high temperatures in order for it to escape from the galaxy) and/or environmental interactions with neighbouring galaxies are responsible for the gas removal from NGC147, NGC185 and NGC205.Science and Technology Facilities Council (STFC); Flemish Fund for Scientific Research (FWO-Vlaanderen); BMVIT (Austria); ESA-PRODEX (Belgium); CEA/CNES (France); DLR (Germany); ASI/INAF (Italy); CICYT/ MCYT (Spain); CSA (Canada); NAOC (China); CEA, CNES, CNRS (France); ASI (Italy); MCINN (Spain); SNSB (Sweden); STFC, UKSA (UK); NASA (USA

Ultrafast three-dimensional imaging of lattice dynamics in individual gold nanocrystals

Key insights into the behavior of materials can be gained by observing their structure as they undergo lattice distortion. Laser pulses on the femtosecond time scale can be used to induce disorder in a "pump-probe" experiment with the ensuing transients being probed stroboscopically with femtosecond pulses of visible light, x-rays, or electrons. Here we report three-dimensional imaging of the generation and subsequent evolution of coherent acoustic phonons on the picosecond time scale within a single gold nanocrystal by means of an x-ray free-electron laser, providing insights into the physics of this phenomenon. Our results allow comparison and confirmation of predictive models based on continuum elasticity theory and molecular dynamics simulations