The Science Case for SPICA Far-Infrared Polarimetry
Draft: 2007 July 5
By C. Darren Dowell1, Paul Goldsmith1, William Langer1, Michael Werner1, Harold
Yorke1
1
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, U.S.A.
Comments are very welcome. I hope we can build an even stronger case for polarimetry
with feedback from scientists in the US, Japan, Europe, and elsewhere.
Abstract
Magnetic fields are predicted to be one of the dominant forces driving and guiding the
flow of material in galaxies and galactic nuclei. Indeed, magnetic fields may be the
determining factor in the structure of the interstellar medium and govern the rate and
distribution of stellar mass formation. In comparison with gravity, pressure, and
kinematics, the effects of magnetic fields in the interstellar medium are relatively difficult
to measure. One of the very few available techniques – far-infrared/(sub)millimeter
polarimetry of dust emission – has been applied to the study of magnetic fields in
molecular cloud cores using suborbital telescopes. Combining this approach with the
sensitivity of large, cold far-infrared space telescope such as SPICA would revolutionize
our understanding of magnetic fields in the interstellar medium of the Galaxy and nearby
spiral galaxies. Among the questions that a SPICA far-infrared polarimeter could address
are:






Do giant molecular clouds form in spiral arms from the swing amplifier effect,
magneto-rotational instability, (magneto-)Jeans instability, or shocks?
Are magnetic fields responsible for some elements of the rich structure in the
ISM?
How does the magnetic support of molecular clouds evolve during the star
formation process?
How do magnetic fields direct the flow of gas in the Galactic center?
What is the structure of the magnetic field at high Galactic latitude?
How does environment affect the magnetic alignment of dust grains?
Table of Contents
1. Brief Review of Far-Infrared/(Sub)millimeter Polarimetry, 1982-2007
2. Worldwide Capabilities in Far-IR/(Sub)mm Polarimetry in the SPICA Era
3. Polarimetry with SPICA
3a. Assumptions for a SPICA Polarimeter
3b. The Magnetic Field Structure of Spiral Galaxies
3c. Star Formation, Cloud Structure, Magnetic Support, and Turbulence
1
3d. Galactic Center
3e. Dust Grain Physics, High-Latitude Magnetic Fields, and Cosmological
Foregrounds
3f. Far-Infrared Polarimetry Technique Relevant to SPICA
4. References
1. Brief Review of Far-Infrared/(Sub)millimeter Polarimetry, 1982-2007
Predictions that the aligned dust grains that produce polarized starlight through
absorption would also produce polarized emission in the far infrared (Stein 1966) were
confirmed through pioneering observations of the Orion core (Cudlip et al 1982;
Hildebrand, Dragovan, & Novak 1984). Continued effort with larger and more sensitive
detectors has shown that polarization at the few percent level is widespread within
molecular cloud cores across the far-infrared through millimeter ( = 60-1300 m)
spectrum (e.g., Hildebrand et al. 1999; Siringo et al. 2004; Matthews et al. 2005). With
near certainty, the polarization in most of these measurements is caused by the alignment
of dust grains with respect to the local magnetic field (Hildebrand 1998; Martin 1971). It
is the potential to map magnetic field structures in the interstellar medium which
motivates much of this experimental and observational work.
Interferometric techniques have been applied to polarimetry at  ≥ 850 m (Akeson et al.
1996; Girart, Rao, & Marrone 2006). As for unpolarized continuum imaging,
inteferometric polarimetry excels at high angular resolution studies of, for example,
protostellar envelopes and disks. “Radio” techniques have also detected polarized
molecular line emission arising from the Goldreich-Kylafis (1981, 1982) effect – also a
probe of magnetic field direction – but mapping results have so far been less extensive
than for dust continuum (e.g., Girart et al. 2004; compare Schleuning 1998).
Polarimetry in the mid-infrared ( = 5-30 m) typically studies a minority population of
dust but offers high angular resolution (e.g., Aitken 1991) and sensitivity to spectral
features of, for example, silicates (Smith et al. 2000)
While emission from polarized dust provides exciting opportunities to measure the
magnetic fields in interstellar clouds, it also hinders our measurements of the Cosmic
Microwave Background (CMB). In the deepening investigation of the properties of the
CMB, cosmologists are now faced with understanding the polarized foreground dust
emission from the Galaxy. Due to the arcminute- and degree-sized beams of CMB
experiments, there is the potential to map magnetic fields over large areas of the Galaxy
(Benoit et al. 2004; Ponthieu et al. 2005; Dowell 2007).
To illustrate the potential of polarization measurements to understand the dynamics of a
wide variety of processes in the interstellar medium, we highlight some selected results
from far-IR/(sub)mm polarimetry in the list and figures below. Since two conventions
are used for displaying polarization vectors in the literature (“E vectors”, which are
parallel to the grain long axes and perpendicular to the local magnetic field; and “B
2
vectors”, which are parallel to the local magnetic field), we have noted which convention
was used in the caption of each figure. Highlights include:








Observations of “magnetic pinches” indicative of cloud core collapse models, but
sometimes seen on larger angular scales (Figure 1)
Magnetic fields lying in the plane of two T Tauri star disks, apparently wound up
from rotation (Figure 2)
An example of a field apparently wound up by a much larger disk – the 3 pc ring
at the Galactic center (Hildebrand et al. 1993)
A possible transition from toroidal magnetic fields in the densest material to
poloidal fields observed in most of the Galactic center volume (Figure 3).
The first, and to date only, detection of polarized far-IR/(sub)mm dust emission
from another galaxy (M82, Greaves et al. 2000)
Estimates of the magnetic field strength in prestellar cores via submillimeter
polarimetry (Kirk, Ward-Thompson, & Crutcher 2006)
Magnetic field patterns revealing the evolutionary history of clouds (e.g., Dotson
1996)
Evidence for multiple populations of far-IR-emitting grains from the spectral
dependence of polarization (Figure 4)
Figure 1 [B vectors]: “Pinched” magnetic fields in regions of star formation. In the
protostellar envelope of NGC 1333 IRAS 4A (left; Girart et al. 2006), the scale of the pinch
is ~1000 AU, roughly the size scale of “pseudodisks” in the star formation models of F. Shu
and collaborators (Galli & Shu 2003). The size scale of the apparent pinch in the high-mass
star formation site DR21 is 100 times larger (right; Dowell et al. 2003).
3
Figure 2 [E vectors]: First detections of polarized dust emission from circumstellar “T
Tauri” disks (Tamura et al. 1999). In both cases, the beam-averaged magnetic field is in the
plane of the disk (as measured with interferometry), consistent with polarization from a
magnetic field wound up by the rotating disk.
Figure 3 [B vectors]: Magnetic field vectors measured in dense neutral clouds in the
Galactic center (left, Chuss et al. 2003). In the densest clouds, the field is toroidal – parallel
to Galactic plane. However, there is evidence that in the lower density material, the field is
poloidal, as in the ionized Radio Arc and as in the accretion model of Uchida, Shibata, &
Sofue (1985).
4
Figure 4: Continuum polarization spectrum of several molecular clouds undergoing highmass star formation, normalized at 350 m (Vaillancourt 2002). The predicted spectrum
from a single grain component is nearly wavelength-indepenent in the far infrared, so
multiple grain components with different polarizing efficiencies are required to explain the
measurements.
The observations have encouraged theoretical modeling of the details of dust grain
alignment (Lazarian 2003) as well as simulated polarization maps for distinguishing
various models of turbulence and grain alignment (Ostriker et al. 2001; Padoan et al.
2001; Heitsch et al. 2001; Pelkonen et al. 2007). It is now an observational challenge to
produce polarization maps with the extent and dynamic range of the simulations (Figure
5).
Figure 5: Predicted polarization emergent from a simulated magnetized medium with
supersonic and super-Alfvenic turbulence which has resulted in the formation of cores
(Padoan et al. 2001). Current far-IR/(sub)mm polarimetry capabilities permit study of only
the cores, and a large, cold space telescope is necessary to investigate the surrounding
medium.
2. Worldwide Capabilities in Far-IR/(Sub)mm Polarimetry in the SPICA Era
Before SPICA is in orbit, Planck will have made the first all-sky map of polarized dust
emission. Planck will have the best sensitivity to polarized dust at 850 m. Planck is
5
likely to detect polarization along lines of sight with visual optical AV as low as 1mag.
and to achieve 0.3% polarization uncertainties where AV > 5 mag. (Sensitivity estimated
from Planck: The Scientific Programme, astroph/0604069, p. 10.) Unfortunately,
Planck’s beam size is 5´, which will average over a lot of cloud structure even within our
Galaxy. However, with Planck observations, we will have, for the first-time, the
“magnetic context” for any subsequent measurement.
Polarimetry will continue with ground-based telescopes. Two particularly powerful
instruments will come on-line by the beginning of the next decade: SCUBA2 and its
polarimeter, and ALMA, both working at  ≥ 450 m, and both having the potential to
make magnetic field maps with thousands of vectors. However, due to the severe
limitations imposed by the atmosphere, there is little sensitivity to dust components of
different temperature, and magnetic field measurements on the largest scales and at the
lowest surface brightnesses are likely to be filtered from the maps.
SOFIA is likely to have a polarimeter during its projected twenty-year lifetime, and it
provides the most direct competition to a SPICA polarimeter for certain science topics
because it has a similar aperture and access to the far-infrared range. However, the
instantaneous sensitivity of a SOFIA polarimeter (Dowell et al. 2003) is ~1000 times
worse than a SPICA polarimeter, and SOFIA’s capability is limited by the relatively
small observing time available, typically 900 hours per year divided among at least five
facility instruments and several PI instruments. Thus, one can expect, at most, 50 hours
per year devoted to mapping magnetic fields in galaxies with SOFIA.
Despite the importance of the magnetic fields to galactic dynamics and star formation,
and the exciting capabilities offered by current technology, there is no far-IR/(sub)mm
polarization mission foreseen in the next decade which matches a SPICA polarimeter in
terms of sensitivity to diffuse dust emission combined with high angular resolution.
Herschel in particular has no polarization capability worthy of mention in this regard.
3. Polarimetry with SPICA
Despite years of concerted effort observing interstellar gas in a variety of tracers and
wavelengths, it is still difficult to quantify the relative importance of turbulence and
magnetic fields in governing the evolution of molecular clouds (e.g., Crutcher 2007).
Furthermore, even if turbulence is the dominant factor in interstellar evolution, it is likely
that much of it is in the form of magnetohydrodynamic waves. More observations which
allow a statistical measure of the contribution of fields are necessary to establish general
rules of thumb, and only comprehensive measurements including the magnetic field have
any hope of telling the full story for any particular interstellar cloud.
SPICA offers the best opportunity to make a breakthrough in our understanding of
interstellar magnetic fields within the next decade. Undoubtedly our own Galaxy would
be the focus of much of the investigation; however, polarimetry of nearby spiral galaxies
– made possible for the first time with SPICA – will provide critical information about
6
galactic dynamics. Of utmost importance is to understand the role of magnetic fields in
galactic nuclei, including our own, where magnetic fields likely guide and/or drive the
flow of material into and out of the galaxy.
3a. Assumptions for a SPICA Polarimeter
The integrated dust spectrum of a typical spiral galaxy peaks at  ~ 100 m (e.g., Dale et
al. 2005). Since the emission from the SPICA telescope is negligible at this wavelength,
it has an enormous sensitivity advantage over contemporaneous facilities for dust in the
20 – 100 K range. Much of the SPICA magnetic field science can be performed with a
polarimeter operating only at 100 m, but see Section 3e for arguments for extended
wavelength coverage.
The sensitivity expected for a SPICA far-infrared camera is discussed by Onaka et al.
(2005). The quoted sensitivity (after 1 hour integration) is dominated by confusion noise
from distant galaxies, so the noise does not integrate down as 1/√t. Therefore,
to estimate the sensitivity of a SPICA 100 m polarimeter observing with a shorter
integration time per beam, we performed a “first-principles” calculation. Since
polarimetry requires high signal-to-noise, the priority targets are likely to be brighter than
~10 MJy/sr, so the photon noise from the target itself is an important contributor. Here,
we consider observations of targets as faint as 40 MJy/sr, which is estimated to
correspond to regions with visual optical depth AV = 1 mag. The photon noise from this
intensity is of order 60 kJy/sr s1/2, or 0.06 mJy s1/2 in one SPICA beam. Achieving
background-limited performance is especially difficult in the far infrared, so in the table
below we consider a baseline instrument with 5 worse sensitivity and only a modest
detector array.
telescope diameter
3.5 m
wavelength
100 m
angular resolution
7˝
point-source sensitivity
0.3 mJy s1/2
extended-source sensitivity
0.3 MJy/sr s1/2
visual optical depth sensitivity
0.01 AV s1/2
1% / √t, t in seconds
polarization uncertainty (P) for AV = 1
number of detectors
100
time to survey 1 square degree with AV ≥ 1
20 hours
to (P) ≤ 0.3%
number of beams in 1 square degree
300,000
integration time per beam
25 sec
Table: Baseline 100 m polarimeter sensitivity
Even with a modest SPICA polarimeter, one may be able to produce polarization maps
with 1,000,000 magnetic field vectors in them.
3b. The Magnetic Field Structure of Spiral Galaxies
7
A particularly exciting prospect for SPICA polarimetry is the study of molecular cloud
formation and evolution in nearby spiral galaxies. Only space polarimeters have the
sensitivity to measure widespread polarized emission from normal spiral galaxies, and
only a far-infrared telescope as large as SPICA has the angular resolution required to
resolve individual Giant Molecular Clouds (GMCs) in the most nearby systems at their 
≈ 100 m spectral peak.
A number of authors have modeled the formation of GMCs within spiral arms. Several
processes could trigger cloud formation, including: the swing amplifier effect (Goldreich
& Lynden-Bell 1965; Julian & Toomre 1966), the magnetorotational instability (Kim,
Ostriker, & Stone 2003), the magneto-Jeans instability (Kim & Ostriker 2006), or largescale shocks. Magnetic fields in the diffuse medium are typically along spiral arms
(Beck 2007), so that can be considered the initial condition of GMC formation. The
swing amplifier operates in the absence of magnetic fields and would twist up weak
fields, so the observational test for that model is a random orientation of GMC fields
relative to the spiral arms. The mechanisms involving magnetic fields have been
simulated (e.g., Figure 6), and the detailed patterns of the field can be compared to
measurements of spiral galaxies such as M31.
Figure 6: Time evolution of GMC formation within a rotationally sheared spiral galaxy
(Kim & Ostriker 2006). The grayscale shows density, and the lines show the magnetic field.
In this model, a density wave shock has caused the gas to become magneto-Jeans unstable.
A survey of M31 would ideally detect polarization toward column densities as low as AV
= 0.5 and therefore sample all of the shielded, neutral gas. Where the column density is
at least that large, polarization uncertainties ≤ 0.3% can be achieved over the 3˚1˚ extent
of the galaxy in 10 days.
8
Figure 7: Spitzer map of M31 (Gordon et al. 2006). The top image at 24 m has 6˝ = 23 pc
resolution, which is approximately the resolution of SPICA at 100 m. A wealth of spiral
substructure is visible at that resolution, including individual Giant Molecular Clouds.
3c. Star Formation, Cloud Structure, Magnetic Support, and Turbulence
Crutcher (2007) summarized how polarimetry may be used to test star formation theory.
He considered two cases: a magnetically-supported cloud, and a turbulence-dominated
cloud. The essential measurements to distinguish these cases are the magnetic field
strength and morphology.
The magnetic field strength can be estimated from far-infrared polarimetry using the
Chandrasekhar-Fermi (1953) method, which has been updated to account for the effects of
beam smoothing and large angle dispersion (Ostriker et al. 2001; Padoan et al. 2001;
Heitsch et al. 2001). A large or small dispersion in polarization position angle indicates an
energetically weak or strong field, respectively, and ancillary observations of density and
velocity can be used to convert to absolute field strength. Radio observations of the
Zeeman effect, although challenging, provide an alternative measure of magnetic field
strength (e.g., Levin et al. 2001). The sensitive Zeeman measurements possible with
ALMA, EVLA, and SKA are highly complementary to the SPICA science. Line widths of
neutral and ionized species provide an additional method for quantifying the line-of-sight
component of the magnetic field (e.g., Lai, Velusamy, & Langer 2003).
Far-IR/(sub)mm polarimetry is the best technique for measuring magnetic field
morphology within molecular clouds, since the effect is measurable with high angular
resolution over a large area. Magnetically-supported clouds have predictable shapes of
the fields and correlations with structure, for example “hourglass” or “pinched” fields
(Figure 1) and fields perpendicular to collapsed “pancake” clouds. In turbulencedominated clouds, the correlation between field direction and cloud structure will be
weaker, and compressive waves may tend to create flattened structures with in-plane
fields. Attempts to measure morphological correlations have reached inconclusive results
so far (Kane et al. 2003; Vallee & Bastein 2000), so more work, with attention to
observational bias, is critical to advance our understanding of cloud formation and
evolution.
9
Statistical approaches will provide strong constraints on star formation theory. In
general, clouds which are in a magnetically-supported phase are evolving much more
slowly than ones dominated by turbulence, so the degree of magnetic support sets the star
formation time scale. Two interesting “axes” to explore with a SPICA polarimeter are
density and evolutionary state. Since magnetic fields are frozen into the material on short
time scales and leak out on longer time scales, the scaling of magnetic field strength with
density indicates the typical manner of cloud evolution (Crutcher 2007). Cloud evolution
is not independent of the stars that form within, so a good sample should include
prestellar cores (magnetically-supported?), clouds with embedded protostars
(transitioning from magnetically subcritical to supercritical?), and HII complexes
(turbulence dominated?).
The interpretation of the data should be rooted in statistical measures referenced to MHD
simulations, especially since “in between” cases with partial magnetic field and turbulent
support may be important. Maps of density and velocity should be incorporated as much
as possible. Histograms, correlations, and power spectra are the statistical techniques
likely to be useful.
Galactic star formation and cloud evolution is an easy target for a SPICA polarimeter,
since polarization can be mapped in degree-sized areas with AV > 1 mag. in 20 hours or
less (Section 3a). While Planck will map large angular scales, SPICA will specialize in
high resolution maps, which are critical for studying galactic nuclei.
Figure 8: Predicted density + polarization maps from a MHD simulation by Ostriker et al.
(2001). The left panel is for a strong magnetic field (left), and the right panel is for a weak
field. These two cases can be easily distinguished by SPICA observations of polarization
and, to a lesser extent, column density. (In this figure, the vectors show polarized intensity:
polarization fraction  total intensity.)
3d. Galactic Center
The lifecycle of the interstellar medium in the central ~100 pc of galaxies is altered by
the effects of increased density, rotation frequency, and tidal forces. The relative
proximity of our own Galactic nucleus allows us to study the effects of the central
10
environment in detail, including environmental influences on the evolution of black
hole/accretion disk systems.
Radio studies of the Galactic center (e.g., LaRosa et al. 2000) show striking evidence for
magnetic fields permeating the ionized medium that are vertical in the Galactic reference
frame. Limited submillimeter polarization vectors sampling the molecular material imply
the magnetic field is largely horizontal (Novak et al. 2003; Chuss et al. 2003; Figure 3),
suggesting a globally azimuthal geometry for this component. This interaction between
vertical and azimuthal fields may influence the spectrum and/or the evolution of galactic
nuclei (Serabyn & Morris 1994; Chuss et al. 2003). If so, then much of the non-thermal
radio luminosity of the central 100 pc of the Galaxy comes from an “environmental”
effect, rather than the activity associated with the black hole.
A SPICA polarization survey of the Galactic center will seek the twisted vertical fields
proposed to explain the ejection of gas out of the plane (Uchida, Shibata, & Sofue 1985;
Novak et al. 2003). Magnetic phenomena in the central ~100 pc represent an extreme
case, but through their study we may learn lessons relevant to our understanding of the
overall morphology of the Galactic field.
3e. Dust Grain Physics, High-Latitude Magnetic Fields, and Cosmological
Foregrounds
The surprising wavelength dependence of far-infrared/submillimeter polarization
(Vaillancourt 2002; Figure 4) and the absence of a complete model for it indicate that
there is more to learn about the alignment of interstellar grains. Effects unrelated to
alignment may be important for the Wien portion of the far-infrared spectrum (Onaka
1995), but multiple grain components with different degrees of alignment are needed to
explain the remainder of the spectrum.
Recent studies of grain alignment theory point to the importance of exposure to radiation
in aligning the grains (e.g., Cho & Lazarian 2005). The theory can be tested by observing
clouds with varying degrees of exposure to stellar radiation. Polarimetry at multiple
wavelengths – selecting the warmer and colder grains – is needed to test models. SPICA
provides, for the first time, the ability to detect far-infrared polarization from very low
column densities where all grains are exposed to radiation.
An especially interesting cloud type to study is the infrared cirrus. The cirrus clouds are
typically found at high Galactic latitudes where confusion is minimal, have no embedded
star formation, and are optically transparent. In addition, they are the dominant
foreground in deep CMB experiments at  > 100 GHz, and a multiwavelength study of
their polarization is key in recovering weak CMB signals. The relationship of magnetic
fields to the cirrus is unknown. Planck will likely detect cirrus polarization in its all-sky
survey, but SPICA will add short-wavelength, high-resolution data, and the pointed
observatory mode allows observing strategies that would maximize the science return.
3f. Far-Infrared Polarimetry Technique Relevant to SPICA
11
Semiconducting bolometers have been shown to have the sensitivity, dynamic range, and
bandwidth necessary for far-IR/(sub)mm polarimetry with suborbital telescopes (Platt et
al. 1991; Dowell 1997; Schleuning et al. 1997; Dowell et al. 1998; Greaves et al. 2003;
Siringo et al. 2004; Masi et al. 2006; Jones et al. 2006; QUaD Collaboration 2007). By
the end of the decade, Planck will map polarization using background-limited
semiconducting bolometers (Planck: The Scientific Programme, astroph/0604069).
Polarimeters using the next generation superconducting bolometers are on the verge of
entering the field (e.g., Holland et al. 2006). In some cases, the bolometers have intrinsic
polarization response, while in other cases, separate polarizers are used.
Since the fractional polarization is typically small (<10%), the polarized signal must be
modulated in some way to distinguish it from the unpolarized signal. Attractive solutions
for SPICA include a continuously rotating half-wave plate (Siringo et al. 2004; Bastien et
al. 2005) or raster scanning (Masi et al. 2006; Jones et al. 2006; QUaD Collaboration
2007).
The polarimetry mode of the Infrared Space Observatory (ISO) far-infrared photometer
used photoconductors and three polarizers in a filter wheel. Observing time and results
were limited (Laureijs & Siebenmorgen 1999) because polarimetry with ISO was not a
high priority at the time of instrument development.
To meet the requirements of a SPICA broadband far-infrared polarimeter, bolometers
operating at 0.1 K can achieve background-limited sensitivity with sufficient dynamic
range and bandwidth. Polarization could be detected with either a rotating half-wave
plate or raster scanning.
The research described in this paper was carried out at the Jet Propulsion Laboratory,
California Institute of Technology, under a contract with the National Aeronautics and
Space Administration.
4. References
Aitken, D. K., Smith, C. H., Gezari, D., McCaughrean, M., & Roche, P. F. ApJ, 380, 419 – “Polarimetric
imaging of the Galactic center at 12.4 microns - The detailed magnetic field structure in the northern
arm and the east-west bar”
Akeson, R. L., Carlstrom, J. E., Phillips, J. A., & Woody, D. P. ApJ, 456, L45 – “Millimeter
Interferometric Polarization Imaging of the Young Stellar Object NGC 1333/IRAS 4A”
Bastien, P., Jenness, T., & Molnar, J. 2005, ASP Conf. Ser. 343, 69 – “A Polarimeter for SCUBA-2”
Beck, R. 2007, EAS Pub Series, 23, 19 – “Magnetic Field Structure from Synchrotron Polarization”
Benoit, A., et al. 2004, A&A, 424, 571 – “First detection of polarization of the submillimetre diffuse
galactic dust emission by Archeops”
Chandrasekhar, S., & Fermi, E. 1953, ApJ, 118, 113 – “Magnetic Fields in Spiral Arms”
Cho, J., & Lazarian, A. 2005, ApJ, 631, 361 – “Grain Alignment by Radiation in Dark Clouds and Cores”
Chuss, D. T., Davidson, J. A., Dotson, J. L., Dowell, C. D., Hildebrand, R. H., Novak, G., & Vaillancourt,
J. E. 2003, ApJ, 599, 1116 – “Magnetic Fields in Cool Clouds within the Central 50 Parsecs of the
Galaxy”
12
Crutcher, R. M. 2007, EAS Pub Series, 23, 37 – “Magnetic Fields in Molecular Clouds”
Cudlip, W., Furniss, I., King, K.J., & Jennings, R. E. 1982, MNRAS, 200, 1169 – “Far infrared
polarimetry of W51A and M42”
Dale, D. A., et al. 2005, ApJ, 633, 857 – “Infrared Spectral Energy Distributions of Nearby Galaxies”
Dotson, J. L. 1996, ApJ, 470, 566 – “Polarization of the Far-Infrared Emission from M17”
Dowell, C. D. 1997, ApJ, 487, 237 – “Far-Infrared Polarization by Absorption in the Molecular Cloud
Sagittarius B2”
Dowell, C. D., Hildebrand, R. H., Schleuning, D. A., Vaillancourt, J. E., Dotson, J. L., Novak, G.,
Renbarger, T., & Houde, M. 1998, ApJ, 504, 588 – “Submillimeter Array Polarimetry with Hertz”
Dowell, C. D., Davidson, J. A., Dotson, J. L., Hildebrand, R. H., Novak, G., Rennick, T. S., &
Vaillancourt, J. E. 2003, SPIE, 4843, 250 – “Hale, a multi-wavelength, far-infrared polarimeter for
SOFIA”
Dowell, C. D. 2007, in Proceedings of 6 th Rencontres du Vietnam, ed. J. Dumarchez – “BICEP: Searching
for the Signature of Inflation from the South Pole”
Galli, D., & Shu, F. H. 1993, ApJ, 417, 243 – “Collapse of Magnetized Molecular Cloud Cores: II.
Numerical Results”
Girart, J. M., Greaves, J. S., Crutcher, R. M., & Lai, S.-P. ApSS, 292, 119 – “BIMA and JCMT
Spectropolarimetric Observations of the CO J = 2 ‑ 1 Line Towards Orion KL/IRc2”
Girart, J. M., Rao, R., & Marrone, D. P. 2006, Science, 313, 812 – “Magnetic Fields in the Formation of
Sun-Like Stars”
Goldreich, P., & Lynden-Bell, D. 1965, MNRAS, 130, 125 – “II. Spiral arms as sheared gravitational
instabilities”
Goldreich, P., & Kylafis, N. D. 1981, ApJ, 243, L75 – “On mapping the magnetic field direction in
molecular clouds by polarization measurements”
Goldreich, P., & Kylafis, N. D. 1982, ApJ, 253, 606 – “Linear polarization of radio frequency lines in
molecular clouds and circumstellar envelopes”
Gordon, K. D., et al. 2006, ApJ, 638, L87 – “Spitzer MIPS Infrared Imaging of M31: Further Evidence for
a Spiral-Ring Composite Structure”
Greaves, J. S., Holland, W. S., Jenness, T., & Hawarden, T. G. 2000, Nature, 404, 732 – “Magnetic field
surrounding the starburst nucleus of the galaxy M82 from polarized dust emission”
Greaves, J. S., et al. 2003, MNRAS, 340, 353 – “A submillimetre imaging polarimeter at the James Clerk
Maxwell Telescope”
Heitsch, F., Zweibel, E. G., Mac Low, M.-M., Li, P., Norman, M. L. 2001, ApJ, 561, 800 – “Magnetic
Field Diagnostics Based on Far-Infrared Polarimetry: Tests Using Numerical Simulations”
Hildebrand, R.H., Dragovan, M., & Novak, G. 1984, ApJ, 284, L51 – “Detection of Submillimeter
Polarization in the Orion Nebula”
Hildebrand, R. H. 1988, QJRAS, 29, 327 – “Magnetic Fields and Stardust”
Hildebrand, R. H., Davidson, J. A., Dotson, J., Figer, D. F., Novak, G., Platt, S. R., & Tao, L. 1993, ApJ,
417, 565 – “Polarization of the Thermal Emission from the Dust Ring at the Center of the Galaxy”
Hildebrand, R. H., Dotson, J. L., Dowell, C. D., Schleuning, D. A., & Vaillancourt, J. E. 1999, ApJ, 516,
834 – “The Far-Infrared Polarization Spectrum: First Results and Analysis”
Holland, W. S., et al. 2006, SPIE, 6275, 45 – “SCUBA-2: a 10,000-pixel submillimeter camera for the
James Clerk Maxwell Telescope”
Jones, W. C., Montroy, T. E., Crill, B. P., Contaldi, C. R., Kisner, T. S., Lange, A. E., MacTavish, C. J.,
Netterfield, C. B., & Ruhl, J. E. 2006, A&A, submitted, astroph/0606606 – “Instrumental and
Analytic Methods for Bolometric Polarimetry”
Julian, W. H., & Toomre, A. 1966, ApJ, 146, 810 – “Non-Axisymmetric Responses of Differentially
Rotating Disks of Stars”
Kane, B. D., Clemens, D. P., Barvainis, R., & Leach, R. W. 1993, ApJ, 411, 708 – “Magnetic fields in
massive cloud cores - Comparison of MILLIPOL and IRAS results”
Kirk, J. M., Ward-Thompson, D., & Crutcher, R. M. 2006, MNRAS, 369, 1445 – “SCUBA polarization
observations of the magnetic fields in the pre-stellar cores L1498 and L1517B”
Kim, W.-T., Ostriker, E. C., & Stones, J. M. 2003, ApJ, 599, 1157 – “Magnetorotationally Driven Galactic
Turbulence and the Formation of Giant Molecular Clouds”
Kim, W.-T., & Ostriker, E. C. 2006, ApJ, 646, 213 – “Formation of Spiral-Arm Spurs and Bound Clouds
in Vertically Stratified Galactic Gas Disks”
13
Lai, S.-P., Velusamy, T., & Langer, W. D. 2003, ApJ, 596, L239 – “The High Angular Resolution
Measurement of Ion and Neutral Spectra as a Probe of The Magnetic Field Structure in DR21(OH)”
Laureijs, R. J., & Siebenmorgen, R., eds. 1999, ESA-SP 435, 31 – “Workshop on ISO Polarisation
Observations”
LaRosa, T. N., Kassim, N. E., Lazio, T. J. W., & Hyman, S. D. 2000, AJ, 119, 207 – “A wide-field 90
centimeter VLA image of the galactic center region”
Lazarian, A. 2003, JQSRT, 79, 881 – “Magnetic Fields via Polarimetry: Progress of Grain Alignment
Theory”
Levin, S. M., Langer, W. D., Velusamy, T., Kuiper, T.B. H., & Crutcher, R.M. 2001, ApJ, 555, 850 –
“Measuring the Magnetic Field Strength in L1498 with Zeeman Splitting Observations of CCS”
Martin, P. G. 1971, 153, 279 – “On Interstellar Grain Alignment by a Magnetic Field”
Masi, S., et al. 2006, A&A, 458, 687 – “Instrument, method, brightness, and polarization maps from the
2003 flight of BOOMERanG”
Matthews, B. C. 2005, in Astronomical Polarimetry: Current Status and Future Directions, ASP Conf. Ser.,
343, 99 – “Polarimetry and Star Formation in the Submillimeter”
Novak, G., Chuss, D. T., Renbarger, T., Griffin, G. S., Newcomb, M. G., Peterson, J. B., Loewenstein, R.
F., Pernic, D., & Dotson, J. L. 2003, ApJ, 583, L83 – “First results from the Submillimeter
Polarimeter for Antarctic Remote Observations: evidence of large-scale toroidal magnetic fields in the
galactic center”
Onaka, T. 1995, ApJ, 439, L21 – “Polarization of thermal emission from aspherical dust grains in an
anisotropic radiation field”
Onaka, T., Kaneda, H., Enya, K., Nakagawa, T., Murakiami, H., Matsuhara, H., & Kataza, H. 2005, SPIE,
5962, 448 – “Development of large aperture cooled telescopes for the space infrared telescope for
cosmology and astrophysics (SPICA) mission”
Ostriker, E. C., Stone, J. M., & Gammie, C. F. 2001, ApJ, 546, 980 – “Density, Velocity, and Magnetic
Field Structure in Turbulent Molecular Cloud Models”
Padoan P., Goodman, A., Draine, B. T., Juvela, M., Nordlund, A., Rognvaldsson, & O. E. 2001, ApJ, 559,
1005 – “Theoretical Models of Polarized Dust Emission from Protostellar Cores”
Pelkonen, V.-M., Juvela, M., & Padoan, P. A&A, 461, 551 – “Simulations of polarized dust emission”
Platt, S. R., Hildebrand, R. H., Pernic, R. J., Davidson, J. A., Novak, G. 1991, PASP, 103, 1193 – “100micron array polarimetry from the Kuiper Airborne Observatory - Instrumentation, techniques, and
first results”
Ponthieu, N. 2005, A&A, 444, 327 – “Temperature and polarization angular power spectra of Galactic dust
radiation at 353 GHz as measured by Archeops”
QUaD Collaboration 2007, ApJ, submitted, arXiv:0705.2359 – “First season QUaD CMB temperature and
polarization power spectra”
Schleuning, D. A., Dowell, C. D., Hildebrand, R. H., Platt, S. R., & Novak, G. 1997, PASP, 109, 307 –
“HERTZ, A Submillimeter Polarimeter”
Schleuning, D. A. 1998, ApJ, 493, 811 – “Far-Infrared and Submillimeter Polarization of OMC-1:
Evidence for Magnetically Regulated Star Formation”
Serabyn, E., & Morris, M. 1994, ApJ, 424, L91 – “The source of the relativistic particles in the galactic
center arc”
Siringo, G., Kreysa, E., Reichertz, L. A., & Menten, K. M. 2004, A&A, 422, 751 – “A new polarimeter for
(sub)millimeter bolometer arrays”
Smith, C. H., Wright, C. M., Aitken, D. K., Roche, P. F., & Hough, J. H. MNRAS, 312, 327 – “Studies in
mid-infrared spectropolarimetry – II. An atlas of spectra”
Stein, W. 1966, ApJ, 144, 318 – “Infrared Radiation from Interstellar Grains”
Uchida, Y., Sofue, Y., & Shibata, K. 1985, Nature, 317, 699 – “Origin of the galactic center lobes”
Vaillancourt, J. E. 2002, ApJS, 142, 53 – “Analysis of the Far-Infrared/Submillimeter Polarization
Spectrum Based on Temperature Maps of Orion”
Vallee, J. P., & Bastien, P. 2000, ApJ, 530, 806 – “Magnetic Orientations and Energetics in Interstellar
Clumps within Small Clouds”
14