QUIJOTE scientific results – I. Measurements of the intensity and polarisation of the anomalous microwave emission in the Perseus molecular complex

Abstract

Anomalous microwave emission (AME) has been observed in numerous sky regions, using different experiments in the frequency range ∼ 10 − 60 GHz. One of the most scrutinized regions is G159.6-18.5, located within the Perseus molecular complex. In this paper we present further observations of this region (194 hours in total over ≈ 250 deg 2 ), both in intensity and in polarization. They span four independent frequency channels between 10 and 20 GHz, and were gathered with QUIJOTE, a new CMB experiment with the goal of measuring the polarization of the CMB and Galactic foregrounds. When combined with other publicly-available intensity data, we achieve the most precise spectrum of the AME measured to date in an individual region, with 13 independent data points between 10 and 50 GHz being dominated by this emission. The four QUIJOTE data points provide the first independent confirmation of the downturn of the AME spectrum at low frequencies, initially unveiled by the COSMOSOMAS experiment in this region. We accomplish an accurate fit of these data using models based on electric dipole emission from spinning dust grains, and also fit some of the parameters on which these models depend.We also present polarization maps with an angular resolution of ≈ 1 • and a sensitivity of ≈ 25 µK/beam. From these maps, which are consistent with zero polarization, we obtain upper limits of Π < 6.3% and < 2.8% (95% C.L.) respectively at 12 and 18 GHz, a frequency range where no AME polarization observations have been reported to date. These constraints are compatible with theoretical predictions of the polarization fraction from electric dipole emission originating from spinning dust grains. At the same time, they rule out several models based on magnetic dipole emission from dust grains ordered in a single magnetic domain, which typically predict higher polarization levels. Future QUIJOTE data in this region may allow more stringent constraints on the polarization level of the AME.

Characterization of foreground emission on degree angular scales for CMBB-mode observations

“…7, together with several regions that have been, or will be, observed by current and future ground-based or ballon-borne CMB experiments. In particular we consider the cases of the LSPE (LSPE Collaboration 2012) and EBEX10K (Chapman et al 2014) proposed balloons, the CLASS (Essinger-Hileman et al 2014), advACT (Calabrese et al 2014), QUIJOTE (Génova-Santos et al 2015), Simons Array ground-based experiment (Suzuki et al 2016), as well as the areas observed by BICEP2/Keck Array (BICEP2 Collaboration I 2014; BICEP2 and Keck Array Collaborations 2015), SPT (Benson et al 2014) and PolarBear (The Polarbear Collaboration 2014).…”

“…On arcminute scales, the dominant contribution is given by gravitational lensing (GL) owing to deflection of CMB photons by cosmological structures along their travel to the observer. Experiments looking at CMB B modes include the European Space Agency (ESA) Planck satellite (Planck Collaboration I 2015), ground-based experiments like PolarBear (The Polarbear Collaboration 2014), the Simons Array (Suzuki et al 2016), BICEP2 (BICEP2 Collaboration I 2014), the Keck Array (BICEP2 and Keck Array Collaborations 2015), SPT (Benson et al 2014), Advanced ACTPol (Calabrese et al 2014), QUBIC (QUBIC Collaboration 2011), QUIJOTE (Génova-Santos et al 2015), CLASS (Essinger-Hileman et al 2014), and balloonborne instruments, such as EBEX (Chapman et al 2014), SPIDER (Fraisse et al 2013), and LSPE (LSPE Collaboration 2012))…”

Planck2015 results

“…The best constraint comes from the Perseus region, which has significant AME emission and relatively little contaminating synchrotron emission. Battistelli et al (2006) reported a weak detection in Perseus at 3.4 +1.5 −1.9 % at 11 GHz, while later measurements obtained by López-Caraballo et al (2011) using WMAP data found a 2σ limit of <1%; Dickinson et al (2011) have also measured a 2σ limit of <1.4% for Perseus (as well as an upper limit of <1.7% in ρ Ophiuchus), and Génova- Santos et al (2015) found a 2σ limit of <2.8% in Perseus at 19 GHz. Recently, Battistelli et al (2015) have claimed to detect polarized AME emission at 21.5 GHz from RCW 175, an H ii region, where they measured a polarization percentage of (2.2 ± 0.2 (random) ± 0.3 (systematic))% at 21.5 GHz.…”

Quantum Suppression of Alignment in Ultrasmall Grains: Microwave Emission From Spinning Dust Will Be Negligibly Polarized

“…Fig. 15.-Measured polarization of AME from the Perseus molecular complex (Battistelli et al 2006;Dickinson et al 2011); the dark clouds Lynds 1622 (Mason et al 2009) and ρ Oph (Dickinson et al 2011); the HII regions G159.6-18.5 (López-Caraballo et al 2011;Génova-Santos et al 2015) and RCW176 (Battistelli et al 2015); and the W43r molecular complex (Génova-Santos et al 2016). …”