98 research outputs found

    The FLASHES Survey I: Integral Field Spectroscopy of the CGM around 48 z=2.3−3.1z=2.3-3.1 QSOs

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    We present the pilot study component of the Fluorescent Lyman-Alpha Structures in High-z Environments (FLASHES) Survey; the largest integral-field spectroscopy survey to date of the circumgalactic medium at z=2.3−3.1z=2.3-3.1. We observed 48 quasar fields between 2015 and 2018 with the Palomar Cosmic Web Imager (Matuszewski et al. 2010). Extended HI Lyman-α\mathrm{\alpha} emission is discovered around 42/48 of the observed quasars, ranging in projected, flux-weighted radius from 21-71 proper kiloparsecs (pkpc), with 26 nebulae exceeding 100 pkpc100\mathrm{~pkpc} in effective diameter. The circularly averaged surface brightness radial profile peaks at a maximum of 1×10−17 erg s−1 cm−2 arcsec−2\mathrm{1\times 10^{-17}~erg~s^{-1}~cm^{-2}~arcsec^{-2}} (2×10−15 erg s−1 cm−2 arcsec−22\times10^{-15}~\mathrm{erg~s^{-1}~cm^{-2}~arcsec^{-2}} adjusted for cosmological dimming) and luminosities range from 1.9×1043 erg s−11.9\times10^{43}~\mathrm{erg~s^{-1}} to −14.1×1043 erg s−1-14.1\times10^{43}~\mathrm{erg~s^{-1}}. The emission appears to have a highly eccentric morphology and a maximum covering factor of 50%50\% (60%60\% for giant nebulae). On average, the nebular spectra are red-shifted with respect to both the systemic redshift and Lyα\alpha peak of the quasar spectrum. The integrated spectra of the nebulae mostly have single or double-peaked line shapes with global dispersions ranging from 167 km s−1167~\mathrm{km~s^{-1}} to 690 km s−1690~\mathrm{km~s^{-1}}, though the individual (Gaussian) components of lines with complex shapes mostly appear to have dispersions ≤400\leq 400 km s−1\mathrm{km~s^{-1}}, and the flux-weighted velocity centroids of the lines vary by thousands of km s−1 \mathrm{km~s^{-1}} with respect to the systemic QSO redshifts. Finally, the root-mean-square velocities of the nebulae are found to be consistent with gravitational motions expected in dark matter halos of mass Mh≃1012.5M⊙\mathrm{M_h \simeq10^{12.5} M_\odot}. We compare these results to existing surveys at both higher and lower redshift

    Enabling effective operational decision making on a Combined Heat and Power System using the 5C architecture

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    The use of Cyber Physical Systems (CPS) to optimise industrial energy systems is an approach which has the potential to positively impact on manufacturing sector energy efficiency. The need to obtain data to facilitate the implementation of a CPS in an industrial energy system is however a complex task which is often implemented in a non-standardised way. The use of the 5C CPS architecture has the potential to standardise this approach. This paper describes a case study where data from a Combined Heat and Power (CHP) system located in a large manufacturing company was fused with grid electricity and gas models as well as a maintenance cost model using the 5C architecture with a view to making effective decisions on its cost efficient operation. A control change implemented based on the cognitive analysis enabled via the 5C architecture implementation has resulted in energy cost savings of over €7400 over a four-month period, with energy cost savings of over €150,000 projected once the 5C architecture is extended into the production environment

    Keck/Palomar Cosmic Web Imagers (KCWI/PCWI) Reveal an Enormous Lyα\alpha Nebula in an Extremely Overdense QSO Pair Field at z=2.45z=2.45

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    Enormous Lyα\alpha nebulae (ELANe) represent the extrema of Lyα\alpha nebulosities. They have detected extents of >200>200 kpc in Lyα\alpha and Lyα\alpha luminosities >1044>10^{44} erg s−1^{-1}. The ELAN population is an ideal laboratory to study the interactions between galaxies and the intergalactic/circumgalactic medium (IGM/CGM) given their brightness and sizes. The current sample size of ELANe is still very small, and the few z≈2z\approx2 ELANe discovered to date are all associated with local overdensities of active galactic nuclei (AGNs). Inspired by these results, we have initiated a survey of ELANe associated with QSO pairs using the Palomar and Keck Cosmic Web Imagers (PCWI/KCWI). In this letter, we present our first result: the discovery of ELAN0101+0201 associated with a QSO pair at z=2.45z=2.45. Our PCWI discovery data shows that, above a 2-σ\sigma surface brightness of 1.2×10−171.2\times10^{-17} \sbunit, the end-to-end size of ELAN0101+0201 is ≳232\gtrsim 232 kpc. We have conducted follow-up observations using KCWI, resolving multiple Lyα\alpha emitting sources within the rectangular field-of-view of ≈130×165\approx 130\times165 projected kpc2^2, and obtaining their emission line profiles at high signal-to-noise ratios. Combining both KCWI and PCWI, our observations confirm that ELAN0101+0201 resides in an extremely overdense environment. Our observations further support that a large amount of cool (T∼104T\sim10^4K) gas could exist in massive halos (M≳1013\gtrsim10^{13}M⊙_\odot) at z≈2z\approx2. Future observations on a larger sample of similar systems will provide statistics of how cool gas is distributed in massive overdensities at high-redshift and strongly constrain the evolution of the intracluster medium (ICM).Comment: Submitted to Astrophysical Journal Letter, 9 pages, 4 figures, Comments Welcom
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