L. Martinis

Cosmology from MAXIMA-1, BOOMERANG, and COBE DMR Cosmic Microwave Background Observations

Recent results from BOOMERANG-98 and MAXIMA-1, taken together with COBE DMR, provide consistent and high signal-to-noise measurements of the cosmic microwave background power spectrum at spherical harmonic multipole bands over 2<l less similar to 800. Analysis of the combined data yields 68% (95%) confidence limits on the total density, Omega(tot) approximately 1.11+/-0.07 (+0.13)(-0.12), the baryon density, Omega(b)h(2) approximately 0.032(+0.005)(-0.004) (+0.009)(-0.008), and the scalar spectral tilt, n(s) approximately 1.01(+0.09)(-0.07) (+0.17)(-0.14). These data are consistent with inflationary initial conditions for structure formation. Taken together with other cosmological observations, they imply the existence of both nonbaryonic dark matter and dark energy in the Universe.

Multiple peaks in the angular power spectrum of the cosmic microwave background: Significance and consequences for cosmology

Multiple Peaks in the Angular Power Spectrum of the Cosmic Microwave Background: Significance and Consequences for Cosmology arXiv:astro-ph/0105296 v1 17 May 2001 P. de Bernardis 1 , P.A.R. Ade 2 , J.J. Bock 3 , J.R. Bond 4 , J. Borrill 5 , A. Boscaleri 6 , K. Coble 7 , C.R. Contaldi 4 , B.P. Crill 8 , G. De Troia 1 , P. Farese 7 , K. Ganga 9 , M. Giacometti 1 , E. Hivon 9 , V.V. Hristov 8 , A. Iacoangeli 1 , A.H. Jaffe 10 , W.C. Jones 8 , A.E. Lange 8 , L. Martinis 11 , S. Masi 1 , P. Mason 8 , P.D. Mauskopf 12 , A. Melchiorri 13 , T. Montroy 7 , C.B. Netterfield 14 , E. Pascale 6 , F. Piacentini 1 , D. Pogosyan 4 , G. Polenta 1 , F. Pongetti 15 , S. Prunet 4 , G. Romeo 15 , J.E. Ruhl 7 , F. Scaramuzzi 11 Dipartimento di Fisica, Universita’ La Sapienza, Roma, Italy Queen Mary and Westfield College, London, UK Jet Propulsion Laboratory, Pasadena, CA, USA Canadian Institute for Theoretical Astrophysics, University of Toronto, Canada National Energy Research Scientific Computing Center, LBNL, Berkeley, CA, USA IROE-CNR, Firenze, Italy Dept. of Physics, Univ. of California, Santa Barbara, CA, USA California Institute of Technology, Pasadena, CA, USA IPAC, California Institute of Technology, Pasadena, CA, USA Department of Astronomy, Space Sciences Lab and Center for Particle Astrophysics, University of CA, Berkeley, CA 94720 USA ENEA, Frascati, Italy Dept. of Physics and Astronomy, Cardiff University, Cardiff CF24 3YB, Wales, UK Nuclear and Astrophysics Laboratory, University of Oxford, Keble Road, Oxford, OX 3RH, UK Depts. of Physics and Astronomy, University of Toronto, Canada Istituto Nazionale di Geofisica, Roma, Italy ABSTRACT Three peaks and two dips have been detected in the power spectrum of the cosmic microwave background from the BOOMERANG experiment, at ∼ 210, 540, 840 and ∼ 420, 750, respec- tively. Using model-independent analyses, we find that all five features are statistically significant and we measure their location and amplitude. These are consistent with the adiabatic inflation- ary model. We also calculate the mean and variance of the peak and dip locations and amplitudes in a large 7-dimensional parameter space of such models, which gives good agreement with the model-independent estimates, and forecast where the next few peaks and dips should be found if the basic paradigm is correct. We test the robustness of our results by comparing Bayesian marginalization techniques on this space with likelihood maximization techniques applied to a sec- ond 7-dimensional cosmological parameter space, using an independent computational pipeline, and find excellent agreement: Ω tot = 1.02 +0.06 vs. 1.04±0.05, Ω b h 2 = 0.022 −0.003 vs. 0.019 +0.005 , and n s = 0.96 −0.09 vs. 0.90±0.08. The deviation in primordial spectral index n s is a consequence of the strong correlation with the optical depth. Subject headings: Cosmic Microwave Background Anisotropy, Cosmology

The BOOMERanG experiment and the curvature of the Universe

We describe the BOOMERanG experiment and its main result, i.e. the measurement of the large scale curvature of the Universe. BOOMERanG is a balloon-borne microwave telescope with sensitive cryogenic detectors. BOOMERanG has measured the angular distribution of the Cosmic Microwave Background on ∼ 3% of the sky, with a resolution of ∼ 10 arcmin and a sensitivity of ∼ 20μK per pixel. The resulting image is dominated by hot and cold spots with rms fluctuations ∼ 80μK and typical size of ∼ 1o. The detailed angular power spectrum of the image features three peaks and two dips at l = (213−13+10), (541−32+20), (845−25+12) and l = (416−12+22), (750−750+20), respectively. Such very characteristic spectrum can be explained assuming that the detected structures are the result of acoustic oscillations in the primeval plasma. In this framework, the measured pattern constrains the density parameter Ω to be 0.85 < Ω < 1.1 (95% confidence interval). Other cosmological parameters, like the spectral index of initial density fluctuations, the density parameter for baryons, dark matter and dark energy, are detected or constrained by the BOOMERanG measurements and by other recent CMB anisotropy experiments. When combined with other cosmological observations, these results depict a new, consistent, cosmological scenario.

Emission of neutrons as a consequence of titanium-deuterium interaction

SummaryThe interaction of deuterium gas with titanium has produced a flow of neutrons in the experiment reported here. This seems to show that it is not necessary to use electrolysis in order to obtain a low-temperature fusion reaction between deuterium nuclei. The experiment confirms also that nonequilibrium conditions are necessary in order to produce such a phenomenon.

The Enhancement and Decrement of the Sunyaev-Zeldovich Effect toward the ROSAT Cluster RX J0658–5557*

We report simultaneous observations of the X-ray cluster RX J0658-5557 at 1.2 and 2 mm made with a double-channel photometer on the Swedish ESO Submillimeter Telescope (SEST) in search of Sunyaev-Zeldovich (SZ) effect. The SZ data were analyzed using the relativistically correct expression for the Comptonization, and we find (2.60?0.79)?10?4 from the detected decrement, which is consistent with that computed using the X-ray (ROSAT and ASCA) observations. The uncertainty includes contributions from statistical uncertainties in the detection, systematics, and calibration. The 1.2 mm channel data alone give rise to a larger Comptonization parameter; this result is discussed in terms of contamination from foreground sources and/or dust in the cluster or from a possible systematic effect. We then make use of a combined analysis of the ROSAT and ASCA X-ray satellite observations to determine an isothermal model for the SZ surface brightness. Since the cluster is asymmetrical and probably in a merging process, models are only approximate. The associated uncertainty can, however, be estimated by exploring a set of alternative models. We then find a factor of 1.3 for the global uncertainty on the Comptonization parameter. Combining the SZ and the X-ray measurements, we determine a value for the Hubble constant. The 2 mm data are consistent with H0(q0=?)=53+38?28 km s-1 Mpc-1, where the uncertainty is dominated by the uncertainty in the models of the X-ray plasma halo.

MITO: the 2.6 m millimetre telescope at Testa Grigia

Abstract We describe a new ground based telescope dedicated to millimetre cosmological research: MITO, Millimetre and Infrared Testagrigia Observatory. The site and all the instrumental subsystems of the telescope have been chosen to perform high sensitivity measurements for wavelengths ranging from 300 micron to 2 millimetre. The possibility of detecting fluctuations of the Cosmic Microwave Background has been explored for some observational strategies. F. Melchiorri

Mapping the CMB sky: The BOOMERanG experiment

We describe the BOOMERanG experiment, a stratospheric balloon telescope intended to measure the Cosmic Microwave Background anisotropy at angular scales between a few degrees and ten arcminutes. The experiment has been optimized for a long duration (7 to 14 days) flight circumnavigating Antarctica at the end of 1998. A test flight was performed on 30 August 1997 in Texas. The level of performance achieved in the test flight was satisfactory and compatible with the requirements for the long duration flight.

New 3He/4He refrigerator

Abstract The sensitivity increase in bolometers obtained by operating temperatures of 1 K (helium-4) and 0.3 K (helium-3), with respect to standard bolometers cooled at pumped 4He temperature, represents in infrared and submillimetric astronomy a remarkable step forward in applications both on large ground telescopes and on stratospheric balloons. The characteristics are introduced of a double stage refrigerator (4He/3He) which allows a temperature of nearly 300 mK to be reached, starting from a temperature of 4.2 K. No moving parts and external links are involved, except for the electric leads, so as to exploit only the condensation and cryosorption cycles of 4He and 3He, without pumping on the main 4He bath.

Balloon-borne 3He cryostat for millimetre bolometric photometry

Abstract A cryostat including a 3 He refrigerator has been designed, built, coupled to a multiband far infrared (FIR) photometer and successfully operated on a balloon flight. Here the cryostat, which is able to cool three bolometers to 0.3 K and one to 1.5 K, is described. The total holding time of the cryostat exceeds 5 days, being limited by exhaustion of the main 4 He and N 2 baths. The autonomy of the 3 He cryostat is more than 50 h, and the recycling time is ≈3 h. The performance of the system in the ARGO 1993 flight is also reported.

Improved 3He/4He refrigerator

Abstract The characteristics and performance of an improved 3 He/ 4 He double stage refrigerator are presented. It is based on the same principle as the previous double stage refrigerator described in reference 1. A new geometry was used to overcome both the extra thermal input due to gas convection in the condensation lines and the long period required to precool at 4.2 K. The improved refrigerator reaches an operative temperature of ≈0.35 K without any external mechanical pumping. The refrigerator has been used to cool 3 He bolometers.