203 research outputs found
QUIJOTE Scientific Results. II. Polarisation Measurements of the Microwave Emission in the Galactic molecular complexes W43 and W47 and supernova remnant W44
We present Q-U-I JOint TEnerife (QUIJOTE) intensity and polarisation maps at
10-20 GHz covering a region along the Galactic plane 24<l<45 deg, |b|<8 deg.
These maps result from 210 h of data, have a sensitivity in polarisation of ~40
muK/beam and an angular resolution of ~1 deg. Our intensity data are crucial to
confirm the presence of anomalous microwave emission (AME) towards the two
molecular complexes W43 (22 sigma) and W47 (8 sigma). We also detect at high
significance (6 sigma) AME associated with W44, the first clear detection of
this emission towards a SNR. The new QUIJOTE polarisation data, in combination
with WMAP, are essential to: i) Determine the spectral index of the synchrotron
emission in W44, beta_sync =-0.62 +/-0.03, in good agreement with the value
inferred from the intensity spectrum once a free-free component is included in
the fit. ii) Trace the change in the polarisation angle associated with Faraday
rotation in the direction of W44 with rotation measure -404 +/- 49 rad/m2. And
iii) set upper limits on the polarisation of W43 of Pi_AME <0.39 per cent (95
per cent C.L.) from QUIJOTE 17~GHz, and <0.22 per cent from WMAP 41 GHz data,
which are the most stringent constraints ever obtained on the polarisation
fraction of the AME. For typical physical conditions (grain temperature and
magnetic field strengths), and in the case of perfect alignment between the
grains and the magnetic field, the models of electric or magnetic dipole
emissions predict higher polarisation fractions.Comment: Accepted for publication in MNRA
Comparison of Magnetic Field Structures on Different Scales in and around the Filamentary Dark Cloud GF 9
New visible polarization data combined with existing IR and FIR polarization
data are used to study how the magnetic field threading the filamentary
molecular cloud GF 9 connects to larger structures in its general environment.
We find that when both visible and NIR polarization data are plotted as a
function of extinction, there is no evidence for a plateau or a saturation
effect in the polarization at Av ~ 1.3 as seen in dark clouds in Taurus. This
lack of saturation effect suggests that even in the denser parts of GF 9 we are
still probing the magnetic field. The visible polarization is smooth and has a
well-defined orientation. The IR data are also well defined but with a
different direction, and the FIR data in the core region are well defined and
with yet another direction, but are randomly distributed in the filament
region. On the scale of a few times the mean radial dimension of the molecular
cloud, it is as if the magnetic field were `blind' to the spatial distribution
of the filaments while on smaller scales within the cloud, in the core region
near the IRAS point source PSC 20503+6006, polarimetry shows a rotation of the
magnetic field lines in these denser phases. Hence, in spite of the fact that
the spatial resolution is not the same in the visible/NIR and in the FIR data,
all the data put together indicate that the field direction changes with the
spatial scale. Finally, the Chandrasekhar and Fermi method is used to evaluate
the magnetic field strength, indicating that the core region is approximately
magnetically critical. A global interpretation of the results is that in the
core region an original poloidal field could have been twisted by a rotating
elongated (core+envelope) structure. There is no evidence for turbulence and
ambipolar diffusion does not seem to be effective at the present time.Comment: 33 pages, 6 tables, 8 figures, Accepted by Ap
Detailed Interstellar Polarimetric Properties of the Pipe Nebula at Core Scales
We use R-band CCD linear polarimetry collected for about 12000 background
field stars in 46 fields of view toward the Pipe nebula to investigate the
properties of the polarization across this dark cloud. Based on archival 2MASS
data we estimate that the surveyed areas present total visual extinctions in
the range 0.6 < Av < 4.6. While the observed polarizations show a well ordered
large scale pattern, with polarization vectors almost perpendicularly aligned
to the cloud's long axis, at core scales one see details that are
characteristics of each core. Although many observed stars present degree of
polarization which are unusual for the common interstellar medium, our analysis
suggests that the dust grains constituting the diffuse parts of the Pipe nebula
seem to have the same properties as the normal Galactic interstellar medium.
Estimates of the second-order structure function of the polarization angles
suggest that most of the Pipe nebula is magnetically dominated and that
turbulence is sub-Alvenic. The Pipe nebula is certainly an interesting region
where to investigate the processes prevailing during the initial phases of low
mass stellar formation.Comment: 20 pages, 23 figures, Accepted for The Astrophysical Journa
Optical polarization and spectral properties of the H-poor superluminous supernovae SN 2021bnw and SN 2021fpl
New optical photometric, spectrocopic and imaging polarimetry data are
combined with publicly available data to study some of the physical properties
of the two H-poor superluminous supernovae (SLSN) SN 2021bnw and SN 2021fpl.
For each SLSN, the best-fit parameters obtained from the magnetar model with
\texttt{MOSFiT} do not depart from the range of parameter obtained on other
SLSNe discussed in the literature. A spectral analysis with \texttt{SYN++}
shows that SN 2021bnw is a W Type, Fast evolver, while SN 2021fpl is a 15bn
Type, Slow evolver. The analysis of the polarimetry data obtained on SN 2021fpl
at four epochs (+1.8, +20.6, +34.1 and +43.0 days, rest-frame) shows polarization detections in the range 0.8--1 . A comparison of the
spectroscopy data suggests that SN 2021fpl underwent a spectral transition a
bit earlier than SN 2015bn, during which, similarly, it could have underwent a
polarization transition. The analysis of the polarimetry data obtained on SN
2021bnw do not show any departure from symmetry of the photosphere at an
empirical diffusion timescale of 2 (+81.1 days rest-frame). This
result is consistent with those on the sample of W Type SLSN observed at
empirical diffusion timescale 1 with that technique, even though it is
not clear the effect of limited spectral windows varying from one object to the
other. Measurements at higher empirical diffusion timescale may be needed to
see any departure from symmetry as it is discussed in the literature for SN
2017egm.Comment: 29 pages, 13 Figures, 15 Tables, submitted to the MNRA
Analytic Metaphysics versus Naturalized Metaphysics: The Relevance of Applied Ontology
The relevance of analytic metaphysics has come under criticism: Ladyman & Ross, for instance, have suggested do discontinue the field. French & McKenzie have argued in defense of analytic metaphysics that it develops tools that could turn out to be useful for philosophy of physics. In this article, we show first that this heuristic defense of metaphysics can be extended to the scientific field of applied ontology, which uses constructs from analytic metaphysics. Second, we elaborate on a parallel by French & McKenzie between mathematics and metaphysics to show that the whole field of analytic metaphysics, being useful not only for philosophy but also for science, should continue to exist as a largely autonomous field
QUIJOTE scientific results - III. Microwave spectrum of intensity and polarization in the Taurus Molecular Cloud complex and L1527
ABSTRACT: We present new intensity and polarization observations of the Taurus Molecular Cloud (TMC) region in the frequency range 10â20 GHz with the multifrequency instrument (MFI) mounted on the first telescope of the Q-U-I-JOint TEnerife (QUIJOTE) experiment. From the combination of the QUIJOTE data with the WMAP 9-yr data release, the Planck second data release, the DIRBE maps, and ancillary data, we detect an anomalous microwave emission (AME) component with flux density SAME,peak = 43.0 ± 7.9 Jy in the TMC and SAME,peak = 10.7 ± 2.7 Jy in the dark cloud nebula L1527, which is part of the TMC. In the TMC the diffuse AME emission peaks around a frequency of 19 GHz, compared with an emission peak about a frequency of 25 GHz in L1527. In the TMC, the best constraint on the level of AME polarization is obtained at the Planck channel of 28.4 GHz, with an upper limit ÏAME < 4.2 per cent (95 per cent C.L.), which reduces to ÏAME < 3.8 per cent (95 per cent C.L.) if the intensity of all the freeâfree, synchrotron and thermal dust components are negligible at this frequency. The same analysis in L1527 leads to ÏAME < 5.3 per cent (95 per cent C.L.) or ÏAME < 4.5 per cent (95 per cent C.L.) under the same assumption. We find that in the TMC and L1527 on average about 80 per cent of the H II gas should be mixed with thermal dust. Our analysis shows how the QUIJOTE-MFI 10â20 GHz data provide key information to properly separate the synchrotron, freeâfree, and AME components.This work has been partially funded by the Spanish Ministry of Economy and Competitiveness (MINECO) under the projects AYA2007-68058-C03-01, AYA2010-21766-C03-02, AYA2012-39475-C02-01, AYA2014-60438-P: ESP2015- 70646.C2-1-R, AYA2015-64508-P and the Consolider-Ingenio project CSD2010-00064 (EPI: Exploring the Physics of Inflation)
The QUIJOTE experiment: project overview and first results
QUIJOTE (Q-U-I JOint TEnerife) is a new polarimeter aimed to characterize the
polarization of the Cosmic Microwave Background and other Galactic and
extragalactic signals at medium and large angular scales in the frequency range
10-40 GHz. The multi-frequency (10-20~GHz) instrument, mounted on the first
QUIJOTE telescope, saw first light on November 2012 from the Teide Observatory
(2400~m a.s.l). During 2014 the second telescope has been installed at this
observatory. A second instrument at 30~GHz will be ready for commissioning at
this telescope during summer 2015, and a third additional instrument at 40~GHz
is now being developed. These instruments will have nominal sensitivities to
detect the B-mode polarization due to the primordial gravitational-wave
component if the tensor-to-scalar ratio is larger than r=0.05.Comment: To appear in "Highlights of Spanish Astrophysics VIII", Proceedings
of the XI Scientific Meeting of the Spanish Astronomical Society, Teruel,
Spain (2014
The relation between the column density structures and the magnetic field orientation in the Vela C molecular complex
We statistically evaluated the relative orientation between gas column density structures, inferred from Herschel submillimetre observations, and the magnetic field projected on the plane of sky, inferred from polarized thermal emission of Galactic dust observed by the Balloon-borne Large-Aperture Submillimetre Telescope for Polarimetry (BLASTPol) at 250, 350, and 500 ÎŒm, towards the Vela C molecular complex. First, we find very good agreement between the polarization orientations in the three wavelength-bands, suggesting that, at the considered common angular resolution of 3.0 that corresponds to a physical scale of approximately 0.61 pc, the inferred magnetic field orientation is not significantly affected by temperature or dust grain alignment effects. Second, we find that the relative orientation between gas column density structures and the magnetic field changes progressively with increasing gas column density, from mostly parallel or having no preferred orientation at low column densities to mostly perpendicular at the highest column densities. This observation is in agreement with previous studies by the Planck collaboration towards more nearby molecular clouds. Finally, we find a correspondence between (a) the trends in relative orientation between the column density structures and the projected magnetic field; and (b) the shape of the column density probability distribution functions (PDFs). In the sub-regions of Vela C dominated by one clear filamentary structure, or "ridges", where the high-column density tails of the PDFs are flatter, we find a sharp transition from preferentially parallel or having no preferred relative orientation at low column densities to preferentially perpendicular at highest column densities. In the sub-regions of Vela C dominated by several filamentary structures with multiple orientations, or "nests", where the maximum values of the column density are smaller than in the ridge-like sub-regions and the high-column density tails of the PDFs are steeper, such a transition is also present, but it is clearly less sharp than in the ridge-like sub-regions. Both of these results suggest that the magnetic field is dynamically important for the formation of density structures in this region
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