Pulsars, transients and relativistic astrophysics

Research group

Research theme

Sub department

About

The death of massive stars - II. Observational constraints on the progenitors of type Ibc supernovae

(2013)

Authors:

John J Eldridge, Morgan Fraser, Stephen J Smartt, Justyn R Maund, R Mark Crockett
More details from the publisher

Initial deep LOFAR observations of Epoch of Reionization windows: I. The North Celestial Pole

ArXiv 1301.163 (2013)

Authors:

S Yatawatta, AG de Bruyn, MA Brentjens, P Labropoulos, VN Pandey, S Kazemi, S Zaroubi, LVE Koopmans, AR Offringa, V Jelic, O Martinez Rubi, V Veligatla, SJ Wijnholds, WN Brouw, G Bernardi, B Ciardi, S Daiboo, G Harker, G Mellema, J Schaye, R Thomas, H Vedantham, E Chapman, FB Abdalla, A Alexov, J Anderson, IM Avruch, F Batejat, ME Bell, MR Bell, M Bentum, P Best, A Bonafede, J Bregman, F Breitling, RH van de Brink, JW Broderick, M Bruggen, J Conway, F de Gasperin, E de Geus, S Duscha, H Falcke, RA Fallows, C Ferrari, W Frieswijk, MA Garrett, JM Griessmeier, AW Gunst, TE Hassall, JWT Hessels, M Hoeft, M Iacobelli, E Juette, A Karastergiou, VI Kondratiev, M Kramer, M Kuniyoshi, G Kuper, J van Leeuwen, P Maat, G Mann, JP McKean, M Mevius, JD Mol, H Munk, R Nijboer, JE Noordam, MJ Norden, E Orru, H Paas, M Pandey-Pommier, R Pizzo, AG Polatidis, W Reich, HJA Rottgering, J Sluman, O Smirnov, B Stappers, M Steinmetz, M Tagger, Y Tang, C Tasse, S ter Veen, R Vermeulen, RJ van Weeren, M Wise, O Wucknitz, P Zarka

Abstract:

The aim of the LOFAR Epoch of Reionization (EoR) project is to detect the spectral fluctuations of the redshifted HI 21cm signal. This signal is weaker by several orders of magnitude than the astrophysical foreground signals and hence, in order to achieve this, very long integrations, accurate calibration for stations and ionosphere and reliable foreground removal are essential. One of the prospective observing windows for the LOFAR EoR project will be centered at the North Celestial Pole (NCP). We present results from observations of the NCP window using the LOFAR highband antenna (HBA) array in the frequency range 115 MHz to 163 MHz. The data were obtained in April 2011 during the commissioning phase of LOFAR. We used baselines up to about 30 km. With about 3 nights, of 6 hours each, effective integration we have achieved a noise level of about 100 microJy/PSF in the NCP window. Close to the NCP, the noise level increases to about 180 microJy/PSF, mainly due to additional contamination from unsubtracted nearby sources. We estimate that in our best night, we have reached a noise level only a factor of 1.4 above the thermal limit set by the noise from our Galaxy and the receivers. Our continuum images are several times deeper than have been achieved previously using the WSRT and GMRT arrays. We derive an analytical explanation for the excess noise that we believe to be mainly due to sources at large angular separation from the NCP.
Details from ArXiV
More details from the publisher

The closest black holes

(2013)

Authors:

Rob Fender, Tom Maccarone, Ian Heywood
More details from the publisher

Spectroscopy of The Largest Ever Gamma-ray Selected BL Lac Sample

(2013)

Authors:

Michael S Shaw, Roger W Romani, Garret Cotter, Stephen E Healey, Peter F Michelson, Anthony CS Readhead, Joseph L Richards, Walter Max-Moerbeck, Oliver G King, William J Potter
More details from the publisher

A compact high energy camera for the cherenkov telescope array

Proceedings of the 33rd International Cosmic Rays Conference, ICRC 2013 2013-October (2013)

Authors:

MK Daniel, RW White, D Berge, J Buckley, PM Chadwick, G Cotter, S Funk, T Greenshaw, N Hidaka, J Hinton, J Lapington, S Markoff, P Moore, S Nolan, S Ohm, A Okumura, D Ross, L Sapozhnikov, J Schmoll, P Sutcliffe, J Sykes, H Tajima, GS Varner, J Vandenbroucke, J Vink, D Williams

Abstract:

The Compact High Energy Camera (CHEC) is a camera-development project involving UK, US, Japanese and Dutch institutes for the dual-mirror Small-Sized Telescopes (SST-2M) of the Cherenkov Telescope Array (CTA). Two CHEC prototypes, based on different photosensors are funded and will be assembled and tested in the UK over the next ≈18 months. CHEC is designed to record flashes of Cherenkov light lasting from a few to a hundred nanoseconds, with typical RMS image width and length of ∼ 0.2◦ × 1.0◦, and has a 9◦ field of view. The physical camera geometry is dictated by the telescope optics: a curved focal surface with radius of curvature 1 m and diameter ∼35 cm is required. CHEC is designed to work with both the ASTRI and GATE SST-2M telescope structures and will include an internal LED flasher system for calibration. The first CHEC prototype will be based on multi-anode photomultipliers (MAPMs) and the second on silicon photomultipliers (SiPMs or MPPCs). The first prototype will soon be installed on the ASTRI SST-2M prototype structure on Mt. Etna.