11,179 research outputs found

    Updated Mass Scaling Relations for Nuclear Star Clusters and a Comparison to Supermassive Black Holes

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    We investigate whether nuclear star clusters and supermassive black holes follow a common set of mass scaling relations with their host galaxy's properties, and hence can be considered to form a single class of central massive object. We have compiled a large sample of galaxies with measured nuclear star cluster masses and host galaxy properties from the literature and fit log-linear scaling relations. We find that nuclear star cluster mass, M_{NC}, correlates most tightly with the host galaxy's velocity dispersion: log M_{NC} = (2.11 \pm 0.31) log (\sigma/54) + (6.63 \pm 0.09), but has a slope dramatically shallower than the relation defined by supermassive black holes. We find that the nuclear star cluster mass relations involving host galaxy (and spheroid) luminosity and stellar and dynamical mass, intercept with but are in general shallower than the corresponding black hole scaling relations. In particular M_{NC} \propto {M}_{Gal,dyn}^{0.55 \pm 0.15}; the nuclear cluster mass is not a constant fraction of its host galaxy or spheroid mass. We conclude that nuclear stellar clusters and supermassive black holes do not form a single family of central massive objects.Comment: 8 pages, 3 figure

    Breaking the law: the M_{bh}-M_{spheroid} mass relations for core-Sersic and Sersic galaxies

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    The popular log-linear relation between supermassive black hole mass, M_bh, and the dynamical mass of the host spheroid, M_sph, is shown to require a significant correction. Core galaxies, typically with M_bh > 2x10^8 M_Sun and thought to be formed in dry merger events, are shown to be well described by a linear relation for which the median black hole mass is 0.36% - roughly double the old value of constancy. Of greater significance is that M_bh ~ (M_sph)^2 among the (non-pseudobulge) lower-mass systems: specifically, log[M_bh/M_Sun] = (1.92+/-0.38)log[M_sph/7x10^{10}M_Sun] + (8.38+/-0.17). `Classical' spheroids hosting a 10^6 M_Sun black hole will have M_bh/M_sph ~ 0.025%. These new relations (i) bring consistency to the relation M_bh ~ sigma^5 and the fact that L ~ sigma^x with exponent x equal to 5 and 2 for bright (M_B < -20.5 mag) and faint spheroids, respectively, (ii) mimic the non-(log-linear) behavior in the M_bh-(Sersic n) diagram, (iii) necessitate the existence of a previously over-looked M_bh ~ L^{2.5} relation for Sersic (i.e.\ not core-Sersic) galaxies, and (iv) resolve past conflicts (in mass prediction) with the M_bh-sigma relation at the low-mass end. Furthermore, the bent nature of the M_bh-M_sph relation for `classical' spheroids will have a host of important implications that relate to (i) galaxy/black hole formation theories, (ii) searches for the fundamental black hole scaling relation, (iii) black hole mass predictions in other galaxies, (iv) alleged pseudobulge detections, (v) estimates of the black hole mass function and mass density based on luminosity functions, (vi) predictions for space-based gravitational wave detections, (vii) connections with nuclear star cluster scaling relations, (viii) evolutionary studies over different cosmic epochs, (ix) comparisons and calibrations matching inactive black hole masses with low-mass AGN data, and more.Comment: 4.5 pages plus reference

    Inconsistent models of artihmetic Part II : The general case

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    The paper establishes the general structure of the inconsistent models of arithmetic of [7]. It is shown that such models are constituted by a sequence of nuclei. The nuclei fall into three segments: the first contains improper nuclei: the second contains proper nuclei with linear chromosomes: the third contains proper nuclei with cyclical chromosomes. The nuclei have periods which are inherited up the ordering. It is also shown that the improper nuclei can have the order type of any ordinal. of the nationals. or of any other order type that can be embedded in the rationals in a certain way

    Simulation of bipartite qudit correlations

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    We present a protocol to simulate the quantum correlations of an arbitrary bipartite state, when the parties perform a measurement according to two traceless binary observables. We show that log(d)\log(d) bits of classical communication is enough on average, where dd is the dimension of both systems. To obtain this result, we use the sampling approach for simulating the quantum correlations. We discuss how to use this method in the case of qudits.Comment: 7 page

    Social creativity: Turning barriers into opportunities for collaborative design

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    ABSTRACT � conceptual (across different communities of practice), requiring support for common ground and shared understanding [Fischer, 2001; Resnick, 1991]; and Design is a ubiquitous activity. The complexity of design problems requires communities rather than individuals to address, frame, and solve them. These design communities have to cope with the following barriers: (1) spatial (across distance), (2) temporal (across time), (3) conceptual (across different communities of practice, and (4) technological (between persons and artifacts). Over the last decade, we have addressed these barriers and have tried to create socio-technical environments to turn them into opportunities for enhancing the social creativity of design communities

    Experimental Design for the Gemini Planet Imager

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    The Gemini Planet Imager (GPI) is a high performance adaptive optics system being designed and built for the Gemini Observatory. GPI is optimized for high contrast imaging, combining precise and accurate wavefront control, diffraction suppression, and a speckle-suppressing science camera with integral field and polarimetry capabilities. The primary science goal for GPI is the direct detection and characterization of young, Jovian-mass exoplanets. For plausible assumptions about the distribution of gas giant properties at large semi-major axes, GPI will be capable of detecting more than 10% of gas giants more massive than 0.5 M_J around stars younger than 100 Myr and nearer than 75 parsecs. For systems younger than 1 Gyr, gas giants more massive than 8 M_J and with semi-major axes greater than 15 AU are detected with completeness greater than 50%. A survey targeting young stars in the solar neighborhood will help determine the formation mechanism of gas giant planets by studying them at ages where planet brightness depends upon formation mechanism. Such a survey will also be sensitive to planets at semi-major axes comparable to the gas giants in our own solar system. In the simple, and idealized, situation in which planets formed by either the "hot-start" model of Burrows et al. (2003) or the core accretion model of Marley et al. (2007), a few tens of detected planets are sufficient to distinguish how planets form.Comment: 15 pages, 9 figures, revised after referee's comments and resubmitted to PAS

    Extending the M_(bh)-sigma diagram with dense nuclear star clusters

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    Abridged: Four new nuclear star cluster masses, M_nc, plus seven upper limits, are provided for galaxies with previously determined black hole masses, M_bh. Together with a sample of 64 galaxies with direct M_bh measurements, 13 of which additionally now have M_nc measurements rather than only upper limits, plus an additional 29 dwarf galaxies with available M_nc measurements and velocity dispersions sigma, an (M_bh + M_nc)-sigma diagram is constructed. Given that major dry galaxy merger events preserve the M_bh/L ratio, and given that L ~ sigma^5 for luminous galaxies, it is first noted that the observation M_bh ~ sigma^5 is consistent with expectations. For the fainter elliptical galaxies it is known that L ~ sigma^2, and assuming a constant M_nc/L ratio (Ferrarese et al.), the expectation that M_nc ~ sigma^2 is in broad agreement with our new observational result that M_nc ~ sigma^{1.57\pm0.24}. This exponent is however in contrast to the value of ~4 which has been reported previously and interpreted in terms of a regulating feedback mechanism from stellar winds.Comment: 6 pages, 2 figures. Submitted 08/08/2011 to MNRAS, first referee report received 19/01/2012, accepted 10/02/201

    Dynamical preparation of EPR entanglement in two-well Bose-Einstein condensates

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    We propose to generate Einstein-Podolsky-Rosen (EPR) entanglement between groups of atoms in a two-well Bose-Einstein condensate using a dynamical process similar to that employed in quantum optics. The local nonlinear S-wave scattering interaction has the effect of creating a spin squeezing at each well, while the tunneling, analogous to a beam splitter in optics, introduces an interference between these fields that results in an inter-well entanglement. We consider two internal modes at each well, so that the entanglement can be detected by measuring a reduction in the variances of the sums of local Schwinger spin observables. As is typical of continuous variable (CV) entanglement, the entanglement is predicted to increase with atom number, and becomes sufficiently strong at higher numbers of atoms that the EPR paradox and steering non-locality can be realized. The entanglement is predicted using an analytical approach and, for larger atom numbers, stochastic simulations based on truncated Wigner function. We find generally that strong tunnelling is favourable, and that entanglement persists and is even enhanced in the presence of realistic nonlinear losses.Comment: 15 pages, 19 figure

    The JCMT Transient Survey: An Extraordinary Submillimetre Flare in the T Tauri Binary System JW 566

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    The binary T Tauri system JW 566 in the Orion Molecular Cloud underwent an energetic, short-lived flare observed at submillimetre wavelengths by the SCUBA-2 instrument on 26 November 2016 (UT). The emission faded by nearly 50% during the 31 minute integration. The simultaneous source fluxes averaged over the observation are 500 +/- 107 mJy/beam at 450 microns and 466 +/- 47 mJy/beam at 850 microns. The 850 micron flux corresponds to a radio luminosity of Lν=8×1019L_{\nu}=8\times10^{19} erg/s/Hz, approximately one order of magnitude brighter (in terms of νLν\nu L_{\nu}) than that of a flare of the young star GMR-A, detected in Orion in 2003 at 3mm. The event may be the most luminous known flare associated with a young stellar object and is also the first coronal flare discovered at sub-mm wavelengths. The spectral index between 450 microns and 850 microns of α=0.11\alpha = 0.11 is broadly consistent with non-thermal emission. The brightness temperature was in excess of 6×1046\times10^{4} K. We interpret this event to be a magnetic reconnection that energised charged particles to emit gyrosynchrotron/synchrotron radiation.Comment: Accepted in ApJ. 16 pages (single column), 6 figure

    The role of Cytochrome P450s towards the control of ticks and other arthropods

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    Introduction Ticks most notably Rhipicephalus (Boophilus) microplus are becoming increasingly resistant to acaricides .This resistance is often broken down into the 3 main mechanisms of detoxification involving 3 groups of enzymes; Cytochrome P450s (CYPs), Glutathione-S-transferases (GST) or Esterases (EST or carboxylesterases) (Foil et al., 2004) Material and Methods Acaricide resistance research to date, has focused on identifying which acaricides are becoming redundant in terms of effectiveness to kill the arthropod. Often, this research uses mortality based experimental procedures (Li et al., 2003; Miller et al., 2005), and investigations into the molecular/enzymatic basis of resistance have focused on GSTs and ESTs rather than CYPs. Another method used in our laboratory investigating the role of CYPs in resistance is employing tick cell cultures as a model system developed in partnership with the Roslin Institute (Bell-Sakyi et al., 2007). This system provides an ideal way to monitor CYP expression before, during and after various treatments such as acaricides. In Anopheles gambiae, expression levels of CYPs, GSTs and ESTs were monitored using a microarray following infection of the mosquito by Plasmodium (Felix et al., 2010). A similar micro array approach could be employed with ticks and mites as more data becomes available. Results Our group is monitoring the expression levels of different CYPs in tick cell lines as well as looking to identify novel CYPs and work on phylogenetic links for those genes between different arthropod groups. We are also investigating polymorphisms between different tick cell lines and different arthropod species. Discussion and Conclusions Among the arthropods, research strongly suggests that the CYP6 (Hemingway et al., 2004) and CYP9families are most highly associated with xenobiotic resistance and a lot of research has been carried out looking at these CYP families in various insect species. In mosquito species some resistance to pesticides is due to their CYP enzymes evolving to detoxify these chemicals at increasing concentrations (Nikou et al., 2003
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