230 research outputs found

    Genome wide linkage scan for loci of musical aptitude in Finnish families: Evidence for a major locus at 4q22

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    ABSTRACT Background: Music perception and performance are comprehensive human cognitive functions and thus provide an excellent model system for studying human behaviour and brain function. However, the molecules involved in mediating music perception and performance are so far uncharacterized

    Long-term Swift and Mets\"ahovi monitoring of SDSS J164100.10+345452.7 reveals multi-wavelength correlated variability

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    We report on the first multi-wavelength Swift monitoring campaign performed on SDSS J164100.10+345452.7, a nearby narrow-line Seyfert 1 galaxy formerly known as radio quiet which was recently detected both in the radio (at 37 GHz) and in the Îł\gamma-rays, which hints at the presence of a relativistic jet. During our 20-month Swift campaign, while pursuing the primary goal of assessing the baseline optical/UV and X-ray properties of J1641, we caught two radio flaring episodes, one each year. Our strictly simultaneous multi-wavelength data closely match the radio flare and allow us to unambiguously link the jetted radio emission of J1641. Indeed, for the X-ray spectra preceding and following the radio flare a simple absorbed power-law model is not an adequate description, and an extra absorption component is required. The average spectrum of J1641 can be best described by an absorbed power law model with a photon index Γ=1.93±0.12\Gamma=1.93\pm0.12, modified by a partially covering neutral absorber with a covering fraction f=0.91−0.03+0.02f=0.91_{-0.03}^{+0.02}. On the contrary, the X-ray spectrum closest to the radio flare does not require such extra absorber and is much harder (Γflare∌0.7±0.4\Gamma_{\rm flare} \sim 0.7\pm0.4), thus implying the emergence of a further, harder spectral component. We interpret this as the jet emission emerging from a gap in the absorber. The fractional variability we derive in the optical/UV and X-ray bands are found to be lower than the typical values reported in the literature, since our observations of J1641 are dominated by the source being in a low state. Under the assumption that the origin of the 37 GHz radio flare is the emergence of a jet from an obscuring screen also observed in the X-rays, the derived total jet power is Pjettot=3.5×1042P^{\rm tot}_{\rm jet}=3.5\times10^{42} erg s−1^{-1}, comparable to the lowest measured in the literature. [Abridged]Comment: Accepted for publication in Astronomy and Astrophysics (13 pages, 4 figures, 8 tables

    Unprecedented extreme high-frequency radio variability in early-stage active galactic nuclei

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    We report on the discovery of one of the most extreme cases of high-frequency radio variability ever measured in active galactic nuclei (AGN), observed on timescales of days and exhibiting variability amplitudes of three to four orders of magnitude. These sources, all radio-weak narrow-line Seyfert 1 (NLS1) galaxies, were discovered some years ago at Aalto University Mets\"ahovi Radio Observatory (MRO) based on recurring flaring at 37 GHz, strongly indicating the presence of relativistic jets. In subsequent observations with the Karl G. Jansky Very Large Array (JVLA) at 1.6, 5.2, and 9.0~GHz no signs of jets were seen. To determine the cause of their extraordinary behaviour, we observed them with the JVLA at 10, 15, 22, 33, and 45 GHz, and with the Very Long Baseline Array (VLBA) at 15 GHz. These observations were complemented with single-dish monitoring at 37 GHz at MRO, and at 15 GHz at Owens Valley Radio Observatory (OVRO). Intriguingly, all but one source either have a steep radio spectrum up to 45 GHz, or were not detected at all. Based on the 37 GHz data the timescales of the radio flares are a few days, and the derived variability brightness temperatures and variability Doppler factors comparable to those seen in blazars. We discuss alternative explanations for their extreme behaviour, but so far no definite conclusions can be made. These sources exhibit radio variability at a level rarely, if ever, seen in AGN. They might represent a new type of jetted AGN, or a new variability phenomenon, and thus deserve our continued attention.Comment: 31 pages, 37 figures, submitted to MNRA
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