230 research outputs found
Genome wide linkage scan for loci of musical aptitude in Finnish families: Evidence for a major locus at 4q22
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
Plant patch hydrodynamics in streams : Mean flow, turbulence, and drag forces
Peer reviewedPreprin
Four novel mutations in the OFD1 (Cxorf5) gene in Finnish patients with oral-facial-digital syndrome 1
Peer reviewe
Long-term Swift and Mets\"ahovi monitoring of SDSS J164100.10+345452.7 reveals multi-wavelength correlated variability
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 -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 , modified by a
partially covering neutral absorber with a covering fraction
. On the contrary, the X-ray spectrum closest to the
radio flare does not require such extra absorber and is much harder
(), 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 erg s, 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
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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