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Displaying Results 1 - 12 of 12 on page 1 of 1

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A Parallel Runtime Framework for Communication Intensive Stream Applications (2013)

Muralidharan, Servesh; Casey, Kevin; Gregg, David

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From Boston to Berlin: Creativity and Digital Media Industries in the Celtic Tiger (2007)

Kerr, Aphra

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Industry & Knowledge Clusters: Principles, Practices, Policy (2003)

Formica, Piero

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Planck early results. IX. XMM-Newton follow-up for validation of Planck cluster candidates (2011)

Aghanim, N.; Arnaud, Martha B.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Balbi, A.; Ba...

Planck early results. IX. XMM-Newton follow-up for validation of Planck cluster candidates (2011)

Aghanim, N.; Arnaud, Martha B.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Balbi, A.; Banday, A.J.; Barreiro, R.B.; Bartelmann, M.; Bartlett, J.G.; Battaner, E.; Benabed, K.; Benoit, A.; Bernard, J.-P.; Bersanelli, M.; Bhatia, R.; Bock, J.J.; Bonaldi, A.; Bond, J.R.; Borrill, J.

Abstract:

We present the XMM-Newton follow-up for confirmation of Planck cluster candidates. Twenty-five candidates have been observed to date using snapshot (∼10 ks) exposures, ten as part of a pilot programme to sample a low range of signal-to-noise ratios (4 < S/N < 6), and a further 15 in a programme to observe a sample of S/N > 5 candidates. The sensitivity and spatial resolution of XMM-Newton allows unambiguous discrimination between clusters and false candidates. The 4 false candidates have S/N ≤ 4.1. A total of 21 candidates are confirmed as extended X-ray sources. Seventeen are single clusters, the majority of which are found to have highly irregular and disturbed morphologies (about ∼70%). The remaining four sources are multiple systems, including the unexpected discovery of a supercluster at z = 0.45. For 20 sources we are able to derive a redshift estimate from the X-ray Fe K line (albeit of variable quality). The new clusters span the redshift range 0.09 <∼ z <∼ 0....

http://mural.maynoothuniversity.ie/3981/

Mark

Planck early results. VIII. The all-sky early Sunyaev-Zeldovich cluster sample (2011)

Ade, P.A.R.; Aghanim, N.; Arnaud, Martha B.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; ...

Planck early results. VIII. The all-sky early Sunyaev-Zeldovich cluster sample (2011)

Ade, P.A.R.; Aghanim, N.; Arnaud, Martha B.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Balbi, A.; Banday, A.J.; Barreiro, R.B.; Bartelmann, M.; Bartlett, J.G.; Battaner, E.; Battye, R.; Benabed, K.; Benoit, A.; Bernard, J.-P.; Bersanelli, M.; Bhatia, R.; Bock, J.J.; Bonaldi, A.

Abstract:

We present the first all-sky sample of galaxy clusters detected blindly by the Planck satellite through the Sunyaev-Zeldovich (SZ) effect from its six highest frequencies. This early SZ (ESZ) sample is comprised of 189 candidates, which have a high signal-to-noise ratio ranging from 6 to 29. Its high reliability (purity above 95%) is further ensured by an extensive validation process based on Planck internal quality assessments and by external cross-identification and follow-up observations. Planck provides the first measured SZ signal for about 80% of the 169 previouslyknown ESZ clusters. Planck furthermore releases 30 new cluster candidates, amongst which 20 meet the ESZ signal-to-noise selection criterion. At the submission date, twelve of the 20 ESZ candidates were confirmed as new clusters, with eleven confirmed using XMM-Newton snapshot observations, most of them with disturbed morphologies and low luminosities. The ESZ clusters are mostly at moderate redshifts (86% with z bel...

http://mural.maynoothuniversity.ie/4033/

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Planck early results. X. Statistical analysis of Sunyaev-Zeldovich scaling relations for X-ray galaxy clusters (2011)

Aghanim, N.; Arnaud, Martha B.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Balbi, A.; Ba...

Planck early results. X. Statistical analysis of Sunyaev-Zeldovich scaling relations for X-ray galaxy clusters (2011)

Aghanim, N.; Arnaud, Martha B.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Balbi, A.; Banday, A.J.; Barreiro, R.B.; Bartelmann, M.; Battaner, E.; Benabed, K.; Benoit, A.; Bernard, J.-P.; Bersanelli, M.; Bhatia, R.; Bock, J.J.; Bonaldi, A.; Bond, J.R.; Borrill, J.; Bouchet, F.R.

Abstract:

All-sky data from the Planck survey and the Meta-Catalogue of X-ray detected Clusters of galaxies (MCXC) are combined to investigate the relationship between the thermal Sunyaev-Zeldovich (SZ) signal and X-ray luminosity. The sample comprises ∼ 1600 X-ray clusters with redshifts up to ∼ 1 and spans a wide range in X-ray luminosity. The SZ signal is extracted for each object individually, and the statistical significance of the measurement is maximised by averaging the SZ signal in bins of X-ray luminosity, total mass, or redshift. The SZ signal is detected at very high significance over more than two decades in X-ray luminosity (1043erg/s . L500E(z)−7/3 . 2 × 1045erg/s). The relation between intrinsic SZ signal and X-ray luminosity is investigated and the measured SZ signal is compared to values predicted from X-ray data. Planck measurements and X-ray based predictions are found to be in excellent agreement over the whole explored luminosity range. No significant deviation from stan...

http://mural.maynoothuniversity.ie/3967/

Mark

Planck early results. XI. Calibration of the local galaxy cluster Sunyaev-Zeldovich scaling relations (2011)

Ade, P.A.R.; Aghanim, N.; Arnaud, Martha B.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; ...

Planck early results. XI. Calibration of the local galaxy cluster Sunyaev-Zeldovich scaling relations (2011)

Ade, P.A.R.; Aghanim, N.; Arnaud, Martha B.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Balbi, A.; Banday, A.J.; Barreiro, R.B.; Bartelmann, M.; Bartlett, J.G.; Battaner, E.; Benabed, K.; Benoit, A.; Bernard, J.-P.; Bersanelli, M.; Bhatia, R.; Bock, J.J.; Bonaldi, A.; Bond, J.R.

Abstract:

We present precise Sunyaev-Zeldovich (SZ) effect measurements in the direction of 62 nearby galaxy clusters (z < 0.5) detected at high signal-tonoise in the first Planck all-sky data set. The sample spans approximately a decade in total mass, 2 × 1014 M < M500 < 2 × 1015 M, where M500 is the mass corresponding to a total density contrast of 500. Combining these high quality Planck measurements with deep XMM-Newton X-ray data, we investigate the relations between D2 A Y500, the integrated Compton parameter due to the SZ effect, and the X-ray-derived gas mass Mg,500, temperature TX, luminosity LX,500, SZ signal analogue YX,500 = Mg,500 × TX, and total mass M500. After correction for the effect of selection bias on the scaling relations, we find results that are in excellent agreement with both X-ray predictions and recently-published ground-based data derived from smaller samples. The present data yield an exceptionally robust, high-quality local reference, and illustrate Pla...

http://mural.maynoothuniversity.ie/3976/

Mark

Planck early results. XII. Cluster Sunyaev-Zeldovich optical scaling relations (2011)

Aghanim, N.; Arnaud, Martha B.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Balbi, A.; Ba...

Planck early results. XII. Cluster Sunyaev-Zeldovich optical scaling relations (2011)

Abstract:

We present the Sunyaev-Zeldovich (SZ) signal-to-richness scaling relation (Y500 − N200) for the MaxBCG cluster catalogue. Employing a multifrequency matched filter on the Planck sky maps, we measure the SZ signal for each cluster by adapting the filter according to weak-lensing calibrated mass-richness relations (N200 −M500).We bin our individual measurements and detect the SZ signal down to the lowest richness systems (N200 = 10) with high significance, achieving a detection of the SZ signal in systems with mass as low as M500 ≈ 5 × 1013 M. The observed Y500 − N200 relation is well modeled by a power law over the full richness range. It has a lower normalisation at given N200 than predicted based on X-ray models and published mass-richness relations. An X-ray subsample, however, does conform to the predicted scaling, and model predictions do reproduce the relation between our measured bin-average SZ signal and measured bin-average X-ray luminosities. At fixed richness, we find an i...

http://mural.maynoothuniversity.ie/3968/

Mark

Planck intermediate results XXXVI. Optical identification and redshifts of Planck SZ sources with telescopes at the Canary Islands observatories (2016)

Ade, P.A.R.; Aghanim, N.; Arnaud, Martha B.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; ...

Mark

Planck intermediate results. XXVI. Optical identification and redshifts of Planck clusters with the RTT150 telescope (2015)

Ade, P.A.R.; Aghanim, N.; Arnaud, Martha B.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; ...

Planck intermediate results. XXVI. Optical identification and redshifts of Planck clusters with the RTT150 telescope (2015)

Ade, P.A.R.; Aghanim, N.; Arnaud, Martha B.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Banday, A.J.; Barreiro, R.B.; Barrena, R.; Bartolo, N.; Battaner, E.; Benabed, K.; Benoit-Lévy, A.; Bernard, J.-P.; Bersanelli, M.; Bielewicz, P.; Bikmaev, I.; Böhringer, H.; Bonaldi, A.; Bonavera, L.

Abstract:

We present the results of approximately three years of observations of Planck Sunyaev-Zeldovich (SZ) sources with the Russian-Turkish 1.5m telescope (RTT150), as a part of the optical follow-up programme undertaken by the Planck collaboration. During this time period approximately 20% of all dark and grey clear time available at the telescope was devoted to observations of Planck objects. Some observations of distant clusters were also done at the 6 m Bolshoi Telescope Alt-azimutalnyi (BTA) of the Special Astrophysical Observatory of the Russian Academy of Sciences. In total, deep, direct images of more than one hundred fields were obtained in multiple filters.We identified 47 previously unknown galaxy clusters, 41 of which are included in the Planck catalogue of SZ sources. The redshifts of 65 Planck clusters were measured spectroscopically and 14 more were measured photometrically. We discuss the details of cluster optical identifications and redshift measurements. We also present...

http://mural.maynoothuniversity.ie/13787/