ball1.gif ARGO

De Bernardis et al. (ARGO-Hercules) and Masi et al. (ARGO-Aries & Taurus) use 0.5, 0.8, 1.2, and 2.0 mm data from the balloon-borne ARGO experiment to constrain CMBR anisotropy. Ratra et al. (1999a) summarize the experiment.

The longest wavelength, 2.0 mm, data is thought to be pure CMBR anisotropy. The FWHM of this beam, assumed to be gaussian, is $\sigma_{\rm FWHM} = 52^\prime
(1 \pm 0.03)$ (one standard deviation uncertainty). The zero-lag window function of the smooth-scan, square wave lockin experiment is

W_\ell = e^{-\sigma_{\rm G}{}^2 (\ell + 0.5)^2}
...t[ H_0 \left( (\ell - 2k) \Phi_0 \right) \right]^2 ,

where $\sigma_{\rm G} = \sigma_{\rm FWHM}/\sqrt{8 {\rm ln} 2}$, $H_0$ is a Struve function, and $\Phi_0 = 0.9^\circ$ is half of the peak-to-peak chop angle.

The first column in the window function file is $\ell$, which runs from 2 to 700. The next column is the 2.0 mm zero-lag $W_\ell$.

Table: ARGO zero-lag Window Function Parameters
$\ell_{e^{-0.5}}$ $\ell_{\rm e}$ $\ell_{\rm m}$ $\ell_{e^{-0.5}}$ $\sqrt{I(W_\ell)}$
60 97.6 109 168 0.551

The quoted bandtemperature values are for the Hercules scan 2.0 mm data and are from Ratra et al. (1999a). They were computed assuming a flat bandpower spectrum and, following Ganga et al., account for the ARGO absolute calibration uncertainty of 5% as well as the beamwidth uncertainty. Aries & Taurus scan results are not quoted since an analysis that accounts for offset and drift removal has not yet been done.

Ratra et al. (1999a,b) use the ARGO data to constrain cosmological parameters.

Fig.: ARGO zero-lag window function. (Postscript version here.) win_ARGO.gif


ball23.gifLink to the experiment webpage.

P. de Bernardis, et al., ``Degree-Scale Observations of Cosmic Microwave Background Anisotropies", Astrophys. J. Lett. 422, L33 (1994).

K. Ganga, B. Ratra, J.O. Gundersen, and N. Sugiyama, ``UCSB South Pole 1994 Cosmic Microwave Background Anisotropy Measurement Constraints on Open and Flat-$\Lambda$ Cold Dark Matter Cosmogonies", Astrophys. J. 484, 7 (1997).

S. Masi, P. de Bernardis, M. de Petris, M. Gervasi, A. Boscaleri, E. Aquilini, L. Martinis, and F. Scaramuzzi, ``Foregrounds Removal and CMB Fluctuations in a Multiband Anisotropy Experiment: ARGO 1993", Astrophys. J. Lett. 463, L47 (1996).

B. Ratra, K. Ganga, R. Stompor, N. Sugiyama, P. de Bernardis, and K.M. Górski, ``ARGO CMB Anisotropy Measurement Constraints on Open and Flat-$\Lambda$ Cold Dark Matter Cosmogonies", Astrophys. J. 510, 11(1999a).

B. Ratra, R. Stompor, K. Ganga, G. Rocha, N. Sugiyama, and K.M. Górski, ``Cosmic Microwave Background Anisotropy Constraints on Open and Flat-$\Lambda$ Cold Dark Matter Cosmogonies from UCSB South Pole, ARGO, MAX, White Dish, and SuZIE Data", Astrophys. J. 517, 549 (1999b).

Bharat Ratra and Tarun Souradeep
Department of Physics, Kansas State University
Last updated: 2000-08-31