Aris Karastergiou: Publications

New Approaches for the Real-Time Detection of Binary Pulsars with the Square Kilometre Array (SKA)

Institute of Electrical and Electronics Engineers (IEEE) (2014) 1-4

Authors:

E van Heerden, A Karastergiou, SJ Roberts, O Smirnov

Initial LOFAR observations of epoch of reionization windows

Astronomy & Astrophysics EDP Sciences 568 (2014) a101

Authors:

V Jelić, AG de Bruyn, M Mevius, FB Abdalla, KMB Asad, G Bernardi, MA Brentjens, S Bus, E Chapman, B Ciardi, S Daiboo, ER Fernandez, A Ghosh, G Harker, H Jensen, S Kazemi, LVE Koopmans, P Labropoulos, O Martinez-Rubi, G Mellema, AR Offringa, VN Pandey, AH Patil, RM Thomas, HK Vedantham, V Veligatla, S Yatawatta, S Zaroubi, A Alexov, J Anderson, IM Avruch, R Beck, ME Bell, MJ Bentum, P Best, A Bonafede, J Bregman, F Breitling, J Broderick, WN Brouw, M Brüggen, HR Butcher, JE Conway, F de Gasperin, E de Geus, A Deller, R-J Dettmar, S Duscha, J Eislöffel, D Engels, H Falcke, RA Fallows, R Fender, C Ferrari, W Frieswijk, MA Garrett, J Grießmeier, AW Gunst, JP Hamaker, TE Hassall, M Haverkorn, G Heald, JWT Hessels, M Hoeft, J Hörandel, A Horneffer, A van der Horst, M Iacobelli, E Juette, A Karastergiou, VI Kondratiev, M Kramer, M Kuniyoshi, G Kuper, J van Leeuwen, P Maat, G Mann, D McKay-Bukowski, JP McKean, H Munk, A Nelles, MJ Norden, H Paas, M Pandey-Pommier, G Pietka, R Pizzo, AG Polatidis, W Reich, H Röttgering, A Rowlinson, AMM Scaife, D Schwarz, M Serylak, O Smirnov, M Steinmetz, A Stewart, M Tagger, Y Tang, C Tasse, S ter Veen, S Thoudam, C Toribio, R Vermeulen, C Vocks, RJ van Weeren, RAMJ Wijers, SJ Wijnholds, O Wucknitz, P Zarka

LOFAR tied-array imaging of Type III solar radio bursts⋆

Astronomy & Astrophysics EDP Sciences 568 (2014) a67

Authors:

DE Morosan, PT Gallagher, P Zucca, R Fallows, EP Carley, G Mann, MM Bisi, A Kerdraon, AA Konovalenko, AL MacKinnon, HO Rucker, B Thidé, J Magdalenić, C Vocks, H Reid, J Anderson, A Asgekar, IM Avruch, MJ Bentum, G Bernardi, P Best, A Bonafede, J Bregman, F Breitling, J Broderick, M Brüggen, HR Butcher, B Ciardi, JE Conway, F de Gasperin, E de Geus, A Deller, S Duscha, J Eislöffel, D Engels, H Falcke, C Ferrari, W Frieswijk, MA Garrett, J Grießmeier, AW Gunst, TE Hassall, JWT Hessels, M Hoeft, J Hörandel, A Horneffer, M Iacobelli, E Juette, A Karastergiou, VI Kondratiev, M Kramer, M Kuniyoshi, G Kuper, P Maat, S Markoff, JP McKean, DD Mulcahy, H Munk, A Nelles, MJ Norden, E Orru, H Paas, M Pandey-Pommier, VN Pandey, G Pietka, R Pizzo, AG Polatidis, W Reich, H Röttgering, AMM Scaife, D Schwarz, M Serylak, O Smirnov, BW Stappers, A Stewart, M Tagger, Y Tang, C Tasse, S Thoudam, C Toribio, R Vermeulen, RJ van Weeren, O Wucknitz, S Yatawatta, P Zarka

Evidence of an asteroid encountering a pulsar

Astrophysical Journal Letters 780:2 (2014)

Authors:

PR Brook, A Karastergiou, S Buchner, SJ Roberts, MJ Keith, S Johnston, RM Shannon

Abstract:

Debris disks and asteroid belts are expected to form around young pulsars due to fallback material from their original supernova explosions. Disk material may migrate inward and interact with a pulsar's magnetosphere, causing changes in torque and emission. Long-term monitoring of PSR J0738-4042 reveals both effects. The pulse shape changes multiple times between 1988 and 2012. The torque, inferred via the derivative of the rotational period, changes abruptly from 2005 September. This change is accompanied by an emergent radio component that drifts with respect to the rest of the pulse. No known intrinsic pulsar processes can explain these timing and radio emission signatures. The data lead us to postulate that we are witnessing an encounter with an asteroid or in-falling debris from a disk. © 2014. The American Astronomical Society. All rights reserved.

Discovery of carbon radio recombination lines in absorption towards cygnus A

Monthly Notices of the Royal Astronomical Society 437:4 (2014) 3506-3515

Authors:

JBR Oonk, RJ van Weeren, F salgado, LK Morabito, AGGM Tielens, HJA Rottgering, A Asgekar, GJ White, A Alexov, J Anderson, IM Avruch, F Batejat, R Beck, ME Bell, I van Bemmel, MJ Bentum, G Bernardi, P Best, A Bonafede, F Breitling, M Brentjens, J Broderick, M Brüggen, HR Butcher, B Ciardi, JE Conway, A Corstanje, F de Gasperin, E de Geus, M de Vos, S Duscha, J Eislöffel, D Engels, J van Enst, H Falcke, RA Fallows, R Fender, C Ferrari, W Frieswijk, MA Garrett, J Griemeier, JP Hamaker, TE Hassa, G Heald, JWT Hessels, M Hoeft, A Horneffer, A van der Horst, M Iacobelli, NJ Jackson, E Juette, A Karastergiou, W Klijn, J Kohler, VI Kondratiev, M Kramer, M Kuniyoshi, G Kuper, J van Leeuwen, P Maat, G Macario, G Mann, S Markoff, JP McKean, M Mevius, JCA Miller-Jones, JD Mol, DD Mulcahy, H Munk, MJ Norden, E Orru, H Paas, M Pandey-Pommier, VN Pandey, R Pizzo, AG Polatidis, W Reich, AMM scaife, A schoenmakers, D schwarz, A shulevski, J sluman, O smirnov, C Sobey, BW Stappers, M steinmetz, J swinbank, M Tagger, Y Tang, C Tasse, S ter Veen, S Thoudam, C Toribio, R van Nieuwpoort, R Vermeulen, C Vocks, C Vogt, RAMJ Wijers, MW Wise, O Wucknitz

Abstract:

We present the first detection of carbon radio recombination line absorption along the line of sight to Cygnus A. The observations were carried out with the Low Frequency Array in the 33-57MHz range. These low-frequency radio observations provide us with a new line of sight to study the diffuse, neutral gas in our Galaxy. To our knowledge this is the first time that foreground Milky Way recombination line absorption has been observed against a bright extragalactic background source. By stacking 48 carbon α lines in the observed frequency range we detect carbon absorption with a signal-to-noise ratio of about 5. The average carbon absorption has a peak optical depth of 2 × 10-4, a line width of 10 km s-1 and a velocity of +4 kms-1 with respect to the local standard of rest. The associated gas is found to have an electron temperature Te ̃ 110K and density ne ̃ 0.06 cm-3. These properties imply that the observed carbon a absorption likely arises in the cold neutral medium of the Orion arm of the Milky Way. Hydrogen and helium lines were not detected to a 3σ peak optical depth limit of 1.5 × 10-4 for a 4 kms-1 channel width. Radio recombination lineσ aσσociated with Cygnuσ A itself were also searched for, but are not detected. We set a 3σ upper limit of 1.5 ×; 10-4 for the peak optical depth of these lines for a 4 kms-1 channel width. © 2013 The Authors Published by 91̽�� University Press on behalf of the Royal Astronomical Society.

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