2015MNRAS.450.2291V

Query : 2015MNRAS.450.2291V

2015MNRAS.450.2291V - Mon. Not. R. Astron. Soc., 450, 2291-2305 (2015/July-1)

Lunar occultation of the diffuse radio sky: LOFAR measurements between 35 and 80 MHz.

VEDANTHAM H.K., KOOPMANS L.V.E., DE BRUYN A.G., WIJNHOLDS S.J., BRENTJENS M., ABDALLA F.B., ASAD K.M.B., BERNARDI G., BUS S., CHAPMAN E., CIARDI B., DAIBOO S., FERNANDEZ E.R., GHOSH A., HARKER G., JELIC V., JENSEN H., KAZEMI S., LAMBROPOULOS P., MARTINEZ-RUBI O., MELLEMA G., MEVIUS M., OFFRINGA A.R., PANDEY V.N., PATIL A.H., THOMAS R.M., VELIGATLA V., YATAWATTA S., ZAROUBI S., ANDERSON J., ASGEKAR A., BELL M.E., BENTUM M.J., BEST P., BONAFEDE A., BREITLING F., BRODERICK J., BRUGGEN M., BUTCHER H.R., CORSTANJE A., DE GASPERIN F., DE GEUS E., DELLER A., DUSCHA S., EISLOFFEL J., ENGELS D., FALCKE H., FALLOWS R.A., FENDER R., FERRARI C., FRIESWIJK W., GARRETT M.A., GRIESSMEIER J., GUNST A.W., HASSALL T.E., HEALD G., HOEFT M., HORANDEL J., IACOBELLI M., JUETTE E., KONDRATIEV V.I., KUNIYOSHI M., KUPER G., MANN G., MARKOFF S., McFADDEN R., McKAY-BUKOWSKI D., McKEAN J.P., MULCAHY D.D., MUNK H., NELLES A., NORDEN M.J., ORRU E., PANDEY-POMMIER M., PIZZO R., POLATIDIS A.G., REICH W., RENTING A., ROTTGERING H., SCHWARZ D., SHULEVSKI A., SMIRNOV O., STAPPERS B.W., STEINMETZ M., SWINBANK J., TAGGER M., TANG Y., TASSE C., TER VEEN S., THOUDAM S., TORIBIO C., VOCKS C., WISE M.W., WUCKNITZ O. and ZARKA P.

Abstract (from CDS):

We present radio observations of the Moon between 35 and 80 MHz to demonstrate a novel technique of interferometrically measuring large-scale diffuse emission extending far beyond the primary beam (global signal) for the first time. In particular, we show that (i) the Moon appears as a negative-flux source at frequencies 35 < ν < 80 MHz since it is `colder' than the diffuse Galactic background it occults, (ii) using the (negative) flux of the lunar disc, we can reconstruct the spectrum of the diffuse Galactic emission with the lunar thermal emission as a reference, and (iii) that reflected RFI (radio-frequency interference) is concentrated at the centre of the lunar disc due to specular nature of reflection, and can be independently measured. Our RFI measurements show that (i) Moon-based Cosmic Dawn experiments must design for an Earth-isolation of better than 80 dB to achieve an RFI temperature <1 mK, (ii) Moon-reflected RFI contributes to a dipole temperature less than 20 mK for Earth-based Cosmic Dawn experiments, (iii) man-made satellite-reflected RFI temperature exceeds 20 mK if the aggregate scattering cross-section of visible satellites exceeds 175 m2 at 800km height, or 15 m2 at 400km height. Currently, our diffuse background spectrum is limited by sidelobe confusion on short baselines (10-15 per cent level). Further refinement of our technique may yield constraints on the redshifted global 21 cm signal from Cosmic Dawn (40 > z > 12) and the Epoch of Reionization (12 > z > 5).

Abstract Copyright: © 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society (2015)

Journal keyword(s): methods: observational - techniques: interferometric - Moon - dark ages, reionization, first stars

Simbad objects: 13

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Number of rows : 13
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 NAME Per B SyG 04 37 04.37535450 +29 40 13.8179631   21.7       ~ 533 2
2 3C 132 rG 04 56 42.922 +22 49 23.06   18.5       ~ 157 1
3 ICRF J050258.4+251625 Sy2 05 02 58.47476282 +25 16 25.2757175   20       ~ 187 1
4 3C 136.1 Sy2 05 16 03.133 +24 58 25.47   17       ~ 88 1
5 ICRF J052109.8+163822 Sy1 05 21 09.88596258 +16 38 22.0515459   19.37 18.84 18.480   ~ 910 1
6 3CR 139.2 Rad 05 24 27.109 +28 12 47.00           ~ 49 1
7 3C 140 Rad 05 26 15.450 +11 40 54.20           ~ 12 2
8 4C 32.18 Rad 05 26 43.436 +32 50 09.34           ~ 58 1
9 M 1 SNR 05 34 31.8 +22 01 03           ~ 6516 1
10 V* CM Tau Psr 05 34 31.9474694616 +22 00 52.153698024           ~ 5476 0
11 IC 443 SNR 06 17 00.0000000 +22 34 11.998901           ~ 1314 1
12 MCG+07-41-003 Bla 19 59 28.35656837 +40 44 02.0972325   16.22 15.10     ~ 2537 2
13 NAME Cas A SNR 23 23 26.0 +58 48 41     14.30     ~ 3033 1

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