Search

Your search keyword '"Callingham, J.R."' showing total 20 results
Start Over Author "Callingham, J.R."
20 results on '"Callingham, J.R."'

1. Probing particle acceleration in Abell 2256: from 16 MHz to gamma rays

Author

Osinga, E., primary, van Weeren, R.J., additional, Brunetti, G., additional, Adam, R., additional, Rajpurohit, K., additional, Botteon, A., additional, Callingham, J.R., additional, Cuciti, V., additional, de Gasperin, F., additional, Miley, G.K., additional, Röttgering, H.J.A., additional, and Shimwell, T.W., additional

Published
2024
Full Text
View/download PDF

2. Milliarcsecond structures of variable-peaked spectrum sources

Author

Ross, Kat, Reynolds, C., Seymour, Nick, Callingham, J.R., Hurley-Walker, Natasha, Bignall, H., Ross, Kat, Reynolds, C., Seymour, Nick, Callingham, J.R., Hurley-Walker, Natasha, and Bignall, H.

Abstract

Spectral variability offers a new technique to identify small scale structures from scintillation, as well as determining the absorption mechanism for peaked-spectrum (PS) radio sources. In this paper, we present very long baseline interferometry (VLBI) imaging using the long baseline array (LBA) of two PS sources, MRC 0225-065 and PMN J0322-4820, identified as spectrally variable from observations with the Murchison Widefield Array (MWA). We compare expected milliarcsecond structures based on the detected spectral variability with direct LBA imaging. We find MRC 0225-065 is resolved into three components, a bright core and two fainter lobes, roughly 430 pc projected separation. A comprehensive analysis of the magnetic field, host galaxy properties, and spectral analysis implies that MRC 0225-065 is a young radio source with recent jet activity over the last-yr. We find PMN J0322-4820 is unresolved on milliarcsecond scales. We conclude PMN J0322-4820 is a blazar with flaring activity detected in 2014 with the MWA. We use spectral variability to predict morphology and find these predictions consistent with the structures revealed by our LBA images.

Published
2023

3. V-LoTSS: The circularly polarised LOFAR Two-metre Sky Survey★

Author

Callingham, J.R., Shimwell, T.W., Vedantham, H.K., Bassa, C.G., O’Sullivan, S.P., Yiu, T.W.H., Bloot, S., Best, P.N., Hardcastle, M.J., Haverkorn, M., Kavanagh, R.D., Lamy, L., Pope, B.J.S., Röttgering, H.J.A., Schwarz, D.J., Tasse, C., Weeren, R.J. van, White, G.J., Zarka, P., Bomans, D.J., Bonafede, A., Bonato, M., Botteon, A., Bruggen, M., Chyży, K.T., Drabent, A., Emig, K.L., Gloudemans, A.J., Gürkan, G., Hajduk, M., Hoang, D.N., Hoeft, M., Iacobelli, M., Kadler, M., Kunert-Bajraszewska, M., Mingo, B., Morabito, L.K., Nair, D.G., Pérez-Torres, M., Ray, T.P., Riseley, C.J., Rowlinson, A., Shulevski, A., Sweijen, F., Timmerman, R., Vaccari, M., Zheng, J., Callingham, J.R., Shimwell, T.W., Vedantham, H.K., Bassa, C.G., O’Sullivan, S.P., Yiu, T.W.H., Bloot, S., Best, P.N., Hardcastle, M.J., Haverkorn, M., Kavanagh, R.D., Lamy, L., Pope, B.J.S., Röttgering, H.J.A., Schwarz, D.J., Tasse, C., Weeren, R.J. van, White, G.J., Zarka, P., Bomans, D.J., Bonafede, A., Bonato, M., Botteon, A., Bruggen, M., Chyży, K.T., Drabent, A., Emig, K.L., Gloudemans, A.J., Gürkan, G., Hajduk, M., Hoang, D.N., Hoeft, M., Iacobelli, M., Kadler, M., Kunert-Bajraszewska, M., Mingo, B., Morabito, L.K., Nair, D.G., Pérez-Torres, M., Ray, T.P., Riseley, C.J., Rowlinson, A., Shulevski, A., Sweijen, F., Timmerman, R., Vaccari, M., and Zheng, J.

Abstract

Contains fulltext : 290183.pdf (Publisher’s version ) (Open Access)

Published
2023

4. Signatures of star-planet interactions across the electromagnetic spectrum

Author

Kavanagh, R.D., Vidotto, A., Vedantham, H., Jardine, M., Klein, B., Callingham, J.R., and Morin, J.

Abstract

Close-in exoplanets can interact with their host stars magnetically, producing a variety of observable signatures at different wavelengths. For these interactions to occur, the planet must orbit inside the Alfvén surface of the stellar wind plasma, the region where magnetic forces dominate. As it is not generally possible to measure the plasma properties of the stellar winds of low-mass stars, the location of the Alfvén surface cannot be determined from observations. However, by coupling both observationally-derived magnetic field maps of the stellar surface and constraints on the stellar wind mass-loss rate with sophisticated magnetohydrodynamic models, we can obtain a 3D picture of the stellar wind plasma. This allows us to determine both the size and shape of the Alfvén surface, which in turn can be used to assess the feasibility of magnetic star-planet interactions occurring. In this talk, I will discuss how this approach allows us to predict and interpret hints of star-planet interactions from radio to X-ray wavelengths. I will illustrate how obtaining near-simultaneous observations at these wavelengths is our best bet for benchmarking these magnetohydrodynamic models.

Published
2022
Full Text
View/download PDF

5. Peculiar Radio–X-Ray Relationship in Active Stars

Author

Vedantham, H.K., Callingham, J.R., Shimwell, T.W., Benz, A.O., Hajduk, M., Ray, T.P., Tasse, C., Drabent, A., Vedantham, H.K., Callingham, J.R., Shimwell, T.W., Benz, A.O., Hajduk, M., Ray, T.P., Tasse, C., and Drabent, A.

Abstract

Contains fulltext : 247404.pdf (Publisher’s version ) (Open Access)

Published
2022

6. Searching for pulsars associated with polarised point sources using LOFAR: Initial discoveries from the TULIPP project

Author

Sobey, C, Bassa, C.G., O’Sullivan, S.P., Callingham, J.R., Tan, C.M., Hessels, J.W.T., Kondratiev, V.I., Stappers, B.W., Tiburzi, C., Heald, G., Shimwell, T., Breton, R.P., Kirwan, M., Vedantham, H.K., Carretti, E., Grießmeier, J.-M., Haverkorn, M., Karastergiou, A., Sobey, C, Bassa, C.G., O’Sullivan, S.P., Callingham, J.R., Tan, C.M., Hessels, J.W.T., Kondratiev, V.I., Stappers, B.W., Tiburzi, C., Heald, G., Shimwell, T., Breton, R.P., Kirwan, M., Vedantham, H.K., Carretti, E., Grießmeier, J.-M., Haverkorn, M., and Karastergiou, A.

Abstract

Contains fulltext : 249740.pdf (Publisher’s version ) (Open Access)

Published
2022

7. Sub-arcsecond imaging with the International LOFAR Telescope: II. Completion of the LOFAR Long-Baseline Calibrator Survey

Author

Jackson, N., Badole, S., Morgan, J., Chhetri, R., Prūsis, K., Nikolajevs, A., Morabito, L., Brentjens, M., Sweijen, F., Iacobelli, M., Orrù, E., Sluman, J., Blaauw, R., Mulder, H., van Dijk, P., Mooney, S., Deller, A., Moldon, J., Callingham, J.R., Harwood, J., Hardcastle, M., Heald, G., Drabent, A., Mckean, J.P., Asgekar, A., Avruch, I.M., Bentum, M.J., Bonafede, A., Brouw, W.N., Brüggen, M., Butcher, H.R., Ciardi, B., Coolen, A., Corstanje, A., Damstra, S., Duscha, S., Eislöffel, J., Falcke, H., Garrett, M., De Gasperin, F., Griessmeier, J.M., Gunst, A.W., van Haarlem, M.P., Hoeft, M., van der Horst, A.J., Jütte, E., Koopmans, L.V.E., Krankowski, A., Maat, P., Mann, G., Miley, G.K., Nelles, A., Norden, M., Paas, M., Pandey, V.N., Pandey-Pommier, M., Pizzo, R.F., Reich, W., Rothkaehl, H., Rowlinson, A., Ruiter, M., Shulevski, A., Schwarz, D.J., Smirnov, O., Tagger, M., Vocks, C., van Weeren, R.J., Wijers, R., Wucknitz, O., Zarka, P., Zensus, J.A., Zucca, P., Jackson, N., Badole, S., Morgan, J., Chhetri, R., Prūsis, K., Nikolajevs, A., Morabito, L., Brentjens, M., Sweijen, F., Iacobelli, M., Orrù, E., Sluman, J., Blaauw, R., Mulder, H., van Dijk, P., Mooney, S., Deller, A., Moldon, J., Callingham, J.R., Harwood, J., Hardcastle, M., Heald, G., Drabent, A., Mckean, J.P., Asgekar, A., Avruch, I.M., Bentum, M.J., Bonafede, A., Brouw, W.N., Brüggen, M., Butcher, H.R., Ciardi, B., Coolen, A., Corstanje, A., Damstra, S., Duscha, S., Eislöffel, J., Falcke, H., Garrett, M., De Gasperin, F., Griessmeier, J.M., Gunst, A.W., van Haarlem, M.P., Hoeft, M., van der Horst, A.J., Jütte, E., Koopmans, L.V.E., Krankowski, A., Maat, P., Mann, G., Miley, G.K., Nelles, A., Norden, M., Paas, M., Pandey, V.N., Pandey-Pommier, M., Pizzo, R.F., Reich, W., Rothkaehl, H., Rowlinson, A., Ruiter, M., Shulevski, A., Schwarz, D.J., Smirnov, O., Tagger, M., Vocks, C., van Weeren, R.J., Wijers, R., Wucknitz, O., Zarka, P., Zensus, J.A., and Zucca, P.

Abstract

The Low-Frequency Array (LOFAR) Long-Baseline Calibrator Survey (LBCS) was conducted between 2014 and 2019 in order to obtain a set of suitable calibrators for the LOFAR array. In this paper, we present the complete survey, building on the preliminary analysis published in 2016 which covered approximately half the survey area. The final catalogue consists of 30 006 observations of 24 713 sources in the northern sky, selected for a combination of high low-frequency radio flux density and flat spectral index using existing surveys (WENSS, NVSS, VLSS, and MSSS). Approximately one calibrator per square degree, suitable for calibration of ≥200 km baselines is identified by the detection of compact flux density, for declinations north of 30° and away from the Galactic plane, with a considerably lower density south of this point due to relative difficulty in selecting flat-spectrum candidate sources in this area of the sky. The catalogue contains indicators of degree of correlated flux on baselines between the Dutch core and each of the international stations, involving a maximum baseline length of nearly 2000 km, for all of the observations. Use of the VLBA calibrator list, together with statistical arguments by comparison with flux densities from lower-resolution catalogues, allow us to establish a rough flux density scale for the LBCS observations, so that LBCS statistics can be used to estimate compact flux densities on scales between 300 mas and 2′, for sources observed in the survey. The survey is used to estimate the phase coherence time of the ionosphere for the LOFAR international baselines, with median phase coherence times of about 2 min varying by a few tens of percent between the shortest and longest baselines. The LBCS can be used to assess the structures of point sources in lower-resolution surveys, with significant reductions in the degree of coherence in these sources on scales between 2′ and 300 mas. The LBCS survey sources show a greater incidence of

Published
2022

8. Radio detection of chemically peculiar stars with LOFAR

Author

Hajduk, Ma., Leto, Paolo, Vedantham, H.K., Trigilio, Corrado, Haverkorn, Marijke, Shimwell, T., Callingham, J.R., White, G.J., Hajduk, Ma., Leto, Paolo, Vedantham, H.K., Trigilio, Corrado, Haverkorn, Marijke, Shimwell, T., Callingham, J.R., and White, G.J.

Abstract

Contains fulltext : 282478.pdf (Publisher’s version ) (Open Access)

Published
2022

9. Wide-band spectral variability of peaked spectrum sources

Author

Ross, Kat, Hurley-Walker, Natasha, Seymour, Nick, Callingham, J.R., Galvin, Tim, Johnston-Hollitt, Melanie, Ross, Kat, Hurley-Walker, Natasha, Seymour, Nick, Callingham, J.R., Galvin, Tim, and Johnston-Hollitt, Melanie

Abstract

Characterizing spectral variability of radio sources is a technique that offers the ability to determine the astrophysics of the intervening media, source structure, emission, and absorption processes. We present broadband (0.072-10 GHz) spectral variability of 15 peaked-spectrum (PS) sources with the Australia Telescope Compact Array (ATCA) and the Murchison Widefield Array (MWA). These 15 PS sources were observed quasi-contemporaneously with ATCA and the MWA four to six times during 2020 with approximately a monthly cadence. Variability was not detected at 1-10 GHz frequencies but 13 of the 15 targets show significant variability with the MWA at megahertz frequencies. We conclude the majority of variability seen at megahertz frequencies is due to refractive interstellar scintillation of a compact component ∼25 mas across. We also identify four PS sources that show a change in their spectral shape at megahertz frequencies. Three of these sources are consistent with a variable optical depth from an inhomogeneous free-free absorbing cloud around the source. One PS source with a variable spectral shape at megahertz frequencies is consistent with an ejection travelling along the jet. We present spectral variability as a method for determining the physical origins of observed variability and for providing further evidence to support absorption models for PS sources where spectral modelling alone is insufficient.

Published
2022

12. Spectral variability of radio sources at low frequencies

Author

Ross, Kat, Callingham, J.R., Hurley-Walker, Natasha, Seymour, Nick, Hancock, Paul, Franzen, Thomas, Morgan, John, White, S.V., Bell, M.E., Patil, P., Ross, Kat, Callingham, J.R., Hurley-Walker, Natasha, Seymour, Nick, Hancock, Paul, Franzen, Thomas, Morgan, John, White, S.V., Bell, M.E., and Patil, P.

Abstract

Spectral variability of radio sources encodes information about the conditions of intervening media, source structure, and emission processes. With new low-frequency radio interferometers observing over wide fractional bandwidths, studies of spectral variability for a large population of extragalactic radio sources are now possible. Using two epochs of observations from the GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey that were taken one year apart, we search for spectral variability across 100-230 MHz for 21 558 sources. We present methodologies for detecting variability in the spectrum between epochs and for classifying the type of variability: either as a change in spectral shape or as a uniform change in flux density across the bandwidth. We identify 323 sources with significant spectral variability over a year-long time-scale. Of the 323 variable sources, we classify 51 of these as showing a significant change in spectral shape. Variability is more prevalent in peaked-spectrum sources, analogous to gigahertz-peaked spectrum and compact steep-spectrum sources, compared to typical radio galaxies. We discuss the viability of several potential explanations of the observed spectral variability, such as interstellar scintillation and jet evolution. Our results suggest that the radio sky in the megahertz regime is more dynamic than previously suggested.

Published
2021

13. Coherent radio emission from a quiescent red dwarf indicative of star-planet interaction

Author

Vedantham, H.K., Callingham, J.R., Shimwell, T.W., Tasse, C., Pope, B.J.S., Bedell, M., Haverkorn, M., Rottgering, H.J.A., White, G.J., Vedantham, H.K., Callingham, J.R., Shimwell, T.W., Tasse, C., Pope, B.J.S., Bedell, M., Haverkorn, M., Rottgering, H.J.A., and White, G.J.

Abstract

Contains fulltext : 220291.pdf (preprint version ) (Open Access)

Published
2020

14. Anisotropic winds in a Wolf-Rayet binary identify a potential gamma-ray burst progenitor

Author

Callingham, J.R., Tuthill, P.G., Pope, B.J.S., Williams, P.M., Crowther, P.A., Edwards, M., Norris, B., and Kedziora-Chudczer, L.

Subjects
Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract

The massive evolved Wolf–Rayet stars sometimes occur in colliding-wind binary systems in which dust plumes are formed as a result of the collision of stellar winds1. These structures are known to encode the parameters of the binary orbit and winds2,3,4. Here we report observations of a previously undiscovered Wolf–Rayet system, 2XMM J160050.7–514245, with a spectroscopically determined wind speed of ~3,400 km s−1. In the thermal infrared, the system is adorned with a prominent ~12″ spiral dust plume, revealed by proper motion studies to be expanding at only ~570 km s−1. As the dust and gas appear to be coeval, these observations are inconsistent with existing models of the dynamics of such colliding-wind systems5,6,7. We propose that this contradiction can be resolved if the system is capable of launching extremely anisotropic winds. Near-critical stellar rotation is known to drive such winds8,9, suggesting that this Wolf–Rayet system may be a Galactic progenitor system for long-duration gamma-ray bursts.

Published
2019

15. The LOFAR Two-metre Sky Survey: II. First data release

Author

Shimwell, T.W., Tasse, C., Hardcastle, M.J., Mechev, A.P., Williams, W.L., Best, P.N., Röttgering, H.J.A., Callingham, J.R., Dijkema, T.J., De Gasperin, F., Hoang, D.N., Hugo, B., Mirmont, M., Oonk, J.B.R., Prandoni, I., Rafferty, D., Sabater, J., Smirnov, O., Van Weeren, R.J., White, G.J., Atemkeng, M., Bester, L., Bonnassieux, E., Brüggen, M., Brunetti, G., Chy, K.T., Cochrane, R., Conway, J.E., Croston, J.H., Danezi, A., Duncan, K., Haverkorn, M., Heald, G.H., Iacobelli, M., Intema, Huib, Jackson, N., Jamrozy, M., Jarvis, M.J., Lakhoo, R., Mevius, M., Miley, G.K., Morabito, L., Morganti, R., Nisbet, D., Orrú, E., Perkins, S., Pizzo, R.F., Schrijvers, C., Smith, D.J.B., Vermeulen, R., Wise, M.W., Alegre, L., Bacon, D.J., Van Bemmel, I.M., Beswick, R.J., Bonafede, A., Botteon, A., Bourke, S., Brienza, M., Calistro Rivera, G., Cassano, R., Clarke, A.O., Conselice, C.J., Dettmar, R.J., Drabent, A., Dumba, C., Emig, K.L., Enßlin, T.A., Ferrari, C., Garrett, M.A., Génova-Santos, R.T., Goyal, A., Gürkan, G., Hale, C., Harwood, J.J., Heesen, V., Hoeft, M., Horellou, C., Jackson, Carole, Kokotanekov, G., Kondapally, R., Kunert-Bajraszewska, M., Mahatma, V., Mahony, E.K., Mandal, S., McKean, J.P., Merloni, A., Mingo, B., Miskolczi, A., Mooney, S., Nikiel-Wroczyński, B., O'Sullivan, S.P., Quinn, J., Reich, W., Roskowiński, C., Rowlinson, A., Savini, F., Saxena, A., Schwarz, D.J., Shulevski, A., Shimwell, T.W., Tasse, C., Hardcastle, M.J., Mechev, A.P., Williams, W.L., Best, P.N., Röttgering, H.J.A., Callingham, J.R., Dijkema, T.J., De Gasperin, F., Hoang, D.N., Hugo, B., Mirmont, M., Oonk, J.B.R., Prandoni, I., Rafferty, D., Sabater, J., Smirnov, O., Van Weeren, R.J., White, G.J., Atemkeng, M., Bester, L., Bonnassieux, E., Brüggen, M., Brunetti, G., Chy, K.T., Cochrane, R., Conway, J.E., Croston, J.H., Danezi, A., Duncan, K., Haverkorn, M., Heald, G.H., Iacobelli, M., Intema, Huib, Jackson, N., Jamrozy, M., Jarvis, M.J., Lakhoo, R., Mevius, M., Miley, G.K., Morabito, L., Morganti, R., Nisbet, D., Orrú, E., Perkins, S., Pizzo, R.F., Schrijvers, C., Smith, D.J.B., Vermeulen, R., Wise, M.W., Alegre, L., Bacon, D.J., Van Bemmel, I.M., Beswick, R.J., Bonafede, A., Botteon, A., Bourke, S., Brienza, M., Calistro Rivera, G., Cassano, R., Clarke, A.O., Conselice, C.J., Dettmar, R.J., Drabent, A., Dumba, C., Emig, K.L., Enßlin, T.A., Ferrari, C., Garrett, M.A., Génova-Santos, R.T., Goyal, A., Gürkan, G., Hale, C., Harwood, J.J., Heesen, V., Hoeft, M., Horellou, C., Jackson, Carole, Kokotanekov, G., Kondapally, R., Kunert-Bajraszewska, M., Mahatma, V., Mahony, E.K., Mandal, S., McKean, J.P., Merloni, A., Mingo, B., Miskolczi, A., Mooney, S., Nikiel-Wroczyński, B., O'Sullivan, S.P., Quinn, J., Reich, W., Roskowiński, C., Rowlinson, A., Savini, F., Saxena, A., Schwarz, D.J., and Shulevski, A.

Published
2019

16. The intergalactic magnetic field probed by a giant radio galaxy

Author

O'Sullivan, S.P., Machalski, J., Eck, C.L. van, Heald, G., Brueggen, M., Fynbo, J.P.U., Haverkorn, M., Morabito, L.K., Callingham, J.R., Orru, E., O'Sullivan, S.P., Machalski, J., Eck, C.L. van, Heald, G., Brueggen, M., Fynbo, J.P.U., Haverkorn, M., Morabito, L.K., Callingham, J.R., and Orru, E.

Abstract

Contains fulltext : 201503.pdf (preprint version ) (Open Access)

Published
2019

17. Systematic effects in LOFAR data: A unified calibration strategy

Author

De Gasperin, F., Dijkema, T.J., Drabent, A., Mevius, M., Rafferty, D., Van Weeren, R., Brüggen, M., Callingham, J.R., Emig, K.L., Heald, G., Intema, Huib, Morabito, L.K., Offringa, A.R., Oonk, R., Orrù, E., Röttgering, H., Sabater, J., Shimwell, T., Shulevski, A., Williams, W., De Gasperin, F., Dijkema, T.J., Drabent, A., Mevius, M., Rafferty, D., Van Weeren, R., Brüggen, M., Callingham, J.R., Emig, K.L., Heald, G., Intema, Huib, Morabito, L.K., Offringa, A.R., Oonk, R., Orrù, E., Röttgering, H., Sabater, J., Shimwell, T., Shulevski, A., and Williams, W.

Abstract

Context. New generation low-frequency telescopes are exploring a new parameter space in terms of depth and resolution. The data taken with these interferometers, for example with the LOw Frequency ARray (LOFAR), are often calibrated in a low signal-to-noise ratio regime and the removal of critical systematic effects is challenging. The process requires an understanding of their origin and properties. Aim. In this paper we describe the major systematic effects inherent to next generation low-frequency telescopes, such as LOFAR. With this knowledge, we introduce a data processing pipeline that is able to isolate and correct these systematic effects. The pipeline will be used to calibrate calibrator observations as the first step of a full data reduction process. Methods. We processed two LOFAR observations of the calibrator 3C 196: the first using the Low Band Antenna (LBA) system at 42-66 MHz and the second using the High Band Antenna (HBA) system at 115-189 MHz. Results. We were able to isolate and correct for the effects of clock drift, polarisation misalignment, ionospheric delay, Faraday rotation, ionospheric scintillation, beam shape, and bandpass. The designed calibration strategy produced the deepest image to date at 54 MHz. The image has been used to confirm that the spectral energy distribution of the average radio source population tends to flatten at low frequencies. Conclusions. We prove that LOFAR systematic effects can be described by a relatively small number of parameters. Furthermore, the identification of these parameters is fundamental to reducing the degrees of freedom when the calibration is carried out on fields that are not dominated by a strong calibrator.

Published
2019

18. Connecting X-ray absorption and 21 cm neutral hydrogen absorption in obscured radio AGN

Author

Moss, V. A., primary, Allison, J. R., additional, Sadler, E. M., additional, Urquhart, R., additional, Soria, R., additional, Callingham, J.R., additional, Curran, S. J., additional, Musaeva, A., additional, Mahony, E. K., additional, Glowacki, M., additional, Farrell, S. A., additional, Bannister, K. W., additional, Chippendale, A. P., additional, Edwards, P. G., additional, Harvey-Smith, L., additional, Heywood, I., additional, Hotan, A. W., additional, Indermuehle, B. T., additional, Lenc, E., additional, Marvil, J., additional, McConnell, D., additional, Reynolds, J. E., additional, Voronkov, M. A., additional, Wark, R. M., additional, and Whiting, M. T., additional

Published
2017
Full Text
View/download PDF

19. The LOFAR Two-metre Sky Survey - IV. First Data Release: Photometric redshifts and rest-frame magnitudes

Author

Duncan, K., Sabater, J., Rottgering, H., Jarvis, M., Smith, D.J.B., Best, P.N., Callingham, J.R., Cochrane, R., Croston, J.H., Mingo, B., Morabito, L., Nisbet, D., Prandoni, I., Shimwell, T. W., Tasse, C., White, G. J., Williams, W. L., Alegre, L., Chyży, K. T., Gürkan, G., Hoeft, M., Kondapally, R., Mechev, A. P., Miley, G. K., Schwarz, D. J., van Weeren, R. J., Duncan, K., Sabater, J., Rottgering, H., Jarvis, M., Smith, D.J.B., Best, P.N., Callingham, J.R., Cochrane, R., Croston, J.H., Mingo, B., Morabito, L., Nisbet, D., Prandoni, I., Shimwell, T. W., Tasse, C., White, G. J., Williams, W. L., Alegre, L., Chyży, K. T., Gürkan, G., Hoeft, M., Kondapally, R., Mechev, A. P., Miley, G. K., Schwarz, D. J., and van Weeren, R. J.

20. The LOFAR Two-metre Sky Survey. II. First data release

Author

Eskil Varenius, Huub Röttgering, Magdalena Kunert-Bajraszewska, Ricardo Genova-Santos, Judith H. Croston, D. Nisbet, R. Lakhoo, R. Kondapally, F. Savini, Joseph R. Callingham, A. O. Clarke, H. R. Stacey, M. H. D. van der Wiel, Isabella Prandoni, Antonia Rowlinson, R. Pizzo, Gianfranco Brunetti, David Bacon, George K. Miley, Marcus Brüggen, L. Alegre, R.-J. Dettmar, C. Dumba, R. J. van Weeren, Volker Heesen, Stephen Bourke, G. Calistro Rivera, A. Botteon, J. Sabater, M. Mirmont, G. Gürkan, Andrea Merloni, Torsten A. Enßlin, Marek Jamrozy, Philip Best, A. Drabent, Marcellin Atemkeng, Glenn J. White, R. C. Vermeulen, Wolfgang Reich, Neal Jackson, Chiara Ferrari, Marco Iacobelli, Huib Intema, J. B. R. Oonk, D. N. Hoang, John Conway, A. Wilber, Marisa Brienza, T. J. Dijkema, B. Webster, M. A. Garrett, Simon Perkins, A. P. Mechev, Shane O'Sullivan, Christopher J. Conselice, I. van Bemmel, Annalisa Bonafede, Oleg Smirnov, John L. Quinn, John McKean, G. Kokotanekov, Subhash C. Mandal, Daniel J. Smith, C. L. Hale, Arti Goyal, Błażej Nikiel-Wroczyński, K. L. Emig, S. Urquhart, Marijke Haverkorn, Timothy W. Shimwell, R. Morganti, Michael W. Wise, Elizabeth K. Mahony, Beatriz Mingo, Arpad Miskolczi, C. A. Jackson, Leah K. Morabito, D. A. Rafferty, A. Saxena, C. Roskowinski, Rachel Cochrane, C. Schrijvers, M. Mevius, Wendy L. Williams, E. Bonnassieux, Rossella Cassano, Matthias Hoeft, Krzysztof T. Chyzy, Dominik J. Schwarz, B. Hugo, Robert Beswick, George Heald, C. Tasse, S. Mooney, Jeremy J. Harwood, Emanuela Orru, Martin J. Hardcastle, Kenneth Duncan, S. S. Sridhar, Cathy Horellou, Matt J. Jarvis, L. Bester, F. de Gasperin, Aleksandar Shulevski, A. Danezi, V. H. Mahatma, Galaxies, Etoiles, Physique, Instrumentation (GEPI), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Joseph Louis LAGRANGE (LAGRANGE), Université Nice Sophia Antipolis (... - 2019) (UNS), Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Astronomy, Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Shimwell T.W., Tasse C., Hardcastle M.J., Mechev A.P., Williams W.L., Best P.N., Rottgering H.J.A., Callingham J.R., Dijkema T.J., De Gasperin F., Hoang D.N., Hugo B., Mirmont M., Oonk J.B.R., Prandoni I., Rafferty D., Sabater J., Smirnov O., Van Weeren R.J., White G.J., Atemkeng M., Bester L., Bonnassieux E., Bruggen M., Brunetti G., Chy K.T., Cochrane R., Conway J.E., Croston J.H., Danezi A., Duncan K., Haverkorn M., Heald G.H., Iacobelli M., Intema H.T., Jackson N., Jamrozy M., Jarvis M.J., Lakhoo R., Mevius M., Miley G.K., Morabito L., Morganti R., Nisbet D., Orru E., Perkins S., Pizzo R.F., Schrijvers C., Smith D.J.B., Vermeulen R., Wise M.W., Alegre L., Bacon D.J., Van Bemmel I.M., Beswick R.J., Bonafede A., Botteon A., Bourke S., Brienza M., Calistro Rivera G., Cassano R., Clarke A.O., Conselice C.J., Dettmar R.J., Drabent A., Dumba C., Emig K.L., Ensslin T.A., Ferrari C., Garrett M.A., Genova-Santos R.T., Goyal A., Gurkan G., Hale C., Harwood J.J., Heesen V., Hoeft M., Horellou C., Jackson C., Kokotanekov G., Kondapally R., Kunert-Bajraszewska M., Mahatma V., Mahony E.K., Mandal S., McKean J.P., Merloni A., Mingo B., Miskolczi A., Mooney S., Nikiel-Wroczynski B., O'Sullivan S.P., Quinn J., Reich W., Roskowinski C., Rowlinson A., Savini F., Saxena A., Schwarz D.J., Shulevski A., Sridhar S.S., Stacey H.R., Urquhart S., Van Der Wiel M.H.D., Varenius E., Webster B., and Wilber A.

Subjects
Astronomy, radio continuum: general, Flux, techniques: image processing, Astrophysics, 01 natural sciences, CLUSTER ENVIRONMENTS, ST/M001229/1, Survey, 010303 astronomy & astrophysics, SOUTHERN SKY, media_common, astro-ph.HE, Physics, CALIBRATION, High Energy Astrophysical Phenomena (astro-ph.HE), image processing [techniques], UNDERSTANDING RADIO POLARIMETRY, ST/R00109X/1, ST/P000096/1, astro-ph.CO, general [radio continuum], Catalog, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics, Noise (radio), Astrophysics - Cosmology and Nongalactic Astrophysics, Cosmology and Nongalactic Astrophysics (astro-ph.CO), astro-ph.GA, media_common.quotation_subject, FOS: Physical sciences, Declination, surveys, 0103 physical sciences, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], AGN, Instrumentation and Methods for Astrophysics (astro-ph.IM), STFC, ST/M001326/1, 010308 nuclear & particles physics, RCUK, Astronomy and Astrophysics, LOFAR, Astrophysics - Astrophysics of Galaxies, Galaxy, Redshift, GALAXY, ST/M001008/1, Space and Planetary Science, Sky, IMAGING SURVEY, DISCOVERY, Astrophysics of Galaxies (astro-ph.GA), FLUX-DENSITY SCALE, Right ascension, EMISSION, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], catalogs, astro-ph.IM
Abstract

The LOFAR Two-metre Sky Survey (LoTSS) is an ongoing sensitive, high-resolution 120-168MHz survey of the entire northern sky for which observations are now 20% complete. We present our first full-quality public data release. For this data release 424 square degrees, or 2% of the eventual coverage, in the region of the HETDEX Spring Field (right ascension 10h45m00s to 15h30m00s and declination 45$^\circ$00$'$00$''$ to 57$^\circ$00$'$00$''$) were mapped using a fully automated direction-dependent calibration and imaging pipeline that we developed. A total of 325,694 sources are detected with a signal of at least five times the noise, and the source density is a factor of $\sim 10$ higher than the most sensitive existing very wide-area radio-continuum surveys. The median sensitivity is S$_{\rm 144 MHz} = 71\,\mu$Jy beam$^{-1}$ and the point-source completeness is 90% at an integrated flux density of 0.45mJy. The resolution of the images is 6$''$ and the positional accuracy is within 0.2$''$. This data release consists of a catalogue containing location, flux, and shape estimates together with 58 mosaic images that cover the catalogued area. In this paper we provide an overview of the data release with a focus on the processing of the LOFAR data and the characteristics of the resulting images. In two accompanying papers we provide the radio source associations and deblending and, where possible, the optical identifications of the radio sources together with the photometric redshifts and properties of the host galaxies. These data release papers are published together with a further $\sim$20 articles that highlight the scientific potential of LoTSS., Comment: 16 figures, 1 table and 22 pages. This paper is part of the LOFAR surveys data release 1 and has been accepted for publication in a special edition of A&A that will appear in Feb 2019, volume 622. The catalogues and images from the data release will be publicly available on lofar-surveys.org upon publication of the journal

Published
2019
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results