-
M. J. Griffin,
C. E. North,
B. Schulz,
A. Amaral-Rogers,
G. Bendo,
J. Bock,
A. Conley, C. D. Dowell,
M. Ferlet,
J. Glenn,
T. Lim,
C. Pearson,
M. Pohlen,
B. Sibthorpe,
L. Spencer,
B. Swinyard,
I. Valtchanov
[show abstract]
[hide abstract]
ABSTRACT: Photometric instruments operating at far infrared to millimetre wavelengths
often have broad spectral passbands (central wavelength/bandwidth ~ 3 or less),
especially those operating in space. A broad passband can result in significant
variation of the beam profile and aperture efficiency across the passband,
effects which thus far have not generally been taken into account in the flux
calibration of such instruments. With absolute calibration uncertainties
associated with the brightness of primary calibration standards now in the
region of 5% or less, variation of the beam properties across the passband can
be a significant contributor to the overall calibration accuracy for extended
emission. We present a calibration framework which takes such variations into
account for both antenna-coupled and absorber-coupled focal plane
architectures. The scheme covers point source and extended source cases, and
also the intermediate case of a semi-extended source profile. We apply the new
method to the Herschel-SPIRE space-borne photometer.
06/2013;
-
G. J. Bendo,
M. J. Griffin,
J. J. Bock,
L. Conversi, C. D. Dowell,
T. Lim,
N. Lu,
C. E. North,
A. Papageorgiou,
C. P. Pearson,
M. Pohlen,
E. T. Polehampton,
B. Schulz,
D. L. Shupe,
B. Sibthorpe,
L. D. Spencer,
B. M. Swinyard,
I. Valtchanov,
C. K. Xu
[show abstract]
[hide abstract]
ABSTRACT: We describe the procedure used to flux calibrate the three-band submillimetre
photometer in the Spectral and Photometric Imaging REceiver (SPIRE) instrument
on the Herschel Space Observatory. This includes the equations describing the
calibration scheme, a justification for using Neptune as the primary
calibration source, a description of the observations and data processing
procedures used to derive flux calibration parameters (for converting from
voltage to flux density) for every bolometer in each array, an analysis of the
error budget in the flux calibration for the individual bolometers, and tests
of the flux calibration on observations of primary and secondary calibrators.
The procedure for deriving the flux calibration parameters is divided into two
parts. In the first part, we use observations of astronomical sources in
conjunction with the operation of the photometer internal calibration source to
derive the unscaled derivatives of the flux calibration curves. To scale the
calibration curves in Jy/beam/V, we then use observations of Neptune in which
the beam of each bolometer is mapped using Neptune observed in a very fine scan
pattern. The total instrumental uncertainties in the flux calibration for the
individual bolometers is ~0.5% for most bolometers, although a few bolometers
have uncertainties of ~1-5% because of issues with the Neptune observations.
Based on application of the flux calibration parameters to Neptune observations
performed using typical scan map observing modes, we determined that
measurements from each array as a whole have instrumental uncertainties of
1.5%. This is considerably less than the absolute calibration uncertainty
associated with the model of Neptune, which is estimated at 4%.
06/2013;
-
Dominik A Riechers,
C M Bradford,
D L Clements, C D Dowell,
I Pérez-Fournon,
R J Ivison,
C Bridge,
A Conley,
Hai Fu,
J D Vieira, [......],
D Scott,
A J Smith,
J G Staguhn,
A Streblyanska,
A P Thomson,
I Valtchanov,
M Viero,
L Wang,
M Zemcov,
J Zmuidzinas
[show abstract]
[hide abstract]
ABSTRACT: Massive present-day early-type (elliptical and lenticular) galaxies probably gained the bulk of their stellar mass and heavy elements through intense, dust-enshrouded starbursts-that is, increased rates of star formation-in the most massive dark-matter haloes at early epochs. However, it remains unknown how soon after the Big Bang massive starburst progenitors exist. The measured redshift (z) distribution of dusty, massive starbursts has long been suspected to be biased low in z owing to selection effects, as confirmed by recent findings of systems with redshifts as high as ∼5 (refs 2-4). Here we report the identification of a massive starburst galaxy at z = 6.34 through a submillimetre colour-selection technique. We unambiguously determined the redshift from a suite of molecular and atomic fine-structure cooling lines. These measurements reveal a hundred billion solar masses of highly excited, chemically evolved interstellar medium in this galaxy, which constitutes at least 40 per cent of the baryonic mass. A 'maximum starburst' converts the gas into stars at a rate more than 2,000 times that of the Milky Way, a rate among the highest observed at any epoch. Despite the overall downturn in cosmic star formation towards the highest redshifts, it seems that environments mature enough to form the most massive, intense starbursts existed at least as early as 880 million years after the Big Bang.
Nature 04/2013; 496(7445):329-333. · 36.28 Impact Factor
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C. Gruppioni,
F. Pozzi,
G. Rodighiero,
I. Delvecchio,
S. Berta,
L. Pozzetti,
G. Zamorani,
P. Andreani,
A. Cimatti,
O. Ilbert, [......],
M. Zemcov,
S. Bardelli,
M. Carollo,
T. Contini,
O. Le Fevre,
S. Lilly,
V. Mainieri,
A. Renzini,
M. Scodeggio,
E. Zucca
[show abstract]
[hide abstract]
ABSTRACT: We exploit the deep and extended far infrared data sets (at 70, 100 and 160
um) of the Herschel GTO PACS Evolutionary Probe (PEP) Survey, in combination
with the HERschel Multi tiered Extragalactic Survey (HerMES) data at 250, 350
and 500 um, to derive the evolution of the restframe 35 um, 60 um, 90 um, and
total infrared (IR) luminosity functions (LFs) up to z~4. We detect very strong
luminosity evolution for the total IR LF combined with a density evolution. In
agreement with previous findings, the IR luminosity density increases steeply
to z~1, then flattens between z~1 and z~3 to decrease at z greater than 3.
Galaxies with different SEDs, masses and sSFRs evolve in very different ways
and this large and deep statistical sample is the first one allowing us to
separately study the different evolutionary behaviours of the individual IR
populations contributing to the IR luminosity density. Galaxies occupying the
well established SFR/stellar mass main sequence (MS) are found to dominate both
the total IR LF and luminosity density at all redshifts, with the contribution
from off MS sources (0.6 dex above MS) being nearly constant (~20% of the total
IR luminosity density) and showing no significant signs of increase with
increasing z over the whole 0.8<z<2.2 range. Sources with mass in the 10<
log(M/Msun) <11 range are found to dominate the total IR LF, with more massive
galaxies prevailing at the bright end of the high-z LF. A two-fold evolutionary
scheme for IR galaxies is envisaged: on the one hand, a starburst-dominated
phase in which the SMBH grows and is obscured by dust, is followed by an AGN
dominated phase, then evolving toward a local elliptical. On the other hand,
moderately starforming galaxies containing a low-luminosity AGN have various
properties suggesting they are good candidates for systems in a transition
phase preceding the formation of steady spiral galaxies.
02/2013;
-
Myrto Symeonidis,
M. Vaccari,
S. Berta,
M. J. Page,
D. Lutz,
V. Arumugam,
H. Aussel,
J. Bock,
A. Boselli,
V. Buat, [......],
B. Schulz,
Douglas Scott,
N. Seymour,
D. L. Shupe,
A. J. Smith,
I. Valtchanov,
L. Wang,
C. K. Xu,
M. Zemcov,
S. Wuyts
[show abstract]
[hide abstract]
ABSTRACT: Using Herschel data from the deepest SPIRE and PACS surveys (HerMES and PEP)
in COSMOS and GOODS (N+S), we examine the dust properties of IR-luminous
(L_IR>10^10 L_sun) galaxies at 0.1<z<2 and determine how these evolve with
cosmic time. The unique angle of this work is the rigorous analysis of survey
selection effects, making this the first study of the star-formation-dominated,
IR-luminous population within a framework almost entirely free of selection
biases. We find that IR-luminous galaxies have SEDs with broad far-IR peaks
characterised by cool/extended dust emission and average dust temperatures in
the 25-45K range. Hot (T>45K) SEDs and cold (T<25K), cirrus-dominated SEDs are
rare, with most sources being within the range occupied by warm starbursts such
as M82 and cool spirals such as M51. We observe a luminosity-temperature (L-T)
relation, where the average dust temperature of log[L_IR/L_sun]=12.5 galaxies
is about 10K higher than that of their log[L_IR/L_sun]=10.5 counterparts.
However, although the increased dust heating in more luminous systems is the
driving factor behind the L-T relation, the increase in dust mass and/or
starburst size with luminosity plays a dominant role in shaping it. Our results
show that the dust conditions in IR-luminous sources evolve with cosmic time:
at high redshift, dust temperatures are on average up to 10K lower than what is
measured locally. This is manifested as a flattening of the L-T relation,
suggesting that (U)LIRGs in the early Universe are typically characterised by a
more extended dust distribution and/or higher dust masses than local equivalent
sources. Interestingly, the evolution in dust temperature is luminosity
dependent, with the fraction of LIRGs with T<35K showing a 2-fold increase from
z~0 to z~2, whereas that of ULIRGs with T<35K shows a 6-fold increase.
02/2013;
-
S. Moyerman,
E. Bierman,
P. A. R. Ade,
R. Aiken,
D. Barkats,
C. Bischoff,
J. J. Bock,
H. C. Chiang, C. D. Dowell,
L. Duband, [......],
H. T. Nguyen,
N. Ponthieu,
C. Pryke,
S. Richter,
G. Rocha,
C. Sheehy,
Y. D. Takahashi,
J. E. Tolan,
E. Wollack,
K. W. Yoon
[show abstract]
[hide abstract]
ABSTRACT: The design and performance of a wide bandwidth linear polarization modulator
based on the Faraday effect is described. Faraday Rotation Modulators (FRMs)
are solid-state polarization switches that are capable of modulation up to ~10
kHz. Six FRMs were utilized during the 2006 observing season in the Background
Imaging of Cosmic Extragalactic Polarization (BICEP) experiment; three FRMs
were used at each of BICEP's 100 and 150 GHz frequency bands. The technology
was verified through high signal-to-noise detection of Galactic polarization
using two of the six FRMs during four observing runs in 2006. The features
exhibit strong agreement with BICEP's measurements of the Galaxy using non-FRM
pixels and with the Galactic polarization models. This marks the first
detection of high signal-to-noise mm-wave celestial polarization using fast,
active optical modulation. The performance of the FRMs during periods when they
were not modulated was also analyzed and compared to results from BICEP's 43
pixels without FRMs.
12/2012;
-
M. P. Viero,
L. Wang,
M. Zemcov,
G. Addison,
A. Amblard,
V. Arumugam,
H. Aussel,
M. Bethermin,
J. Bock,
A. Boselli, [......],
N. Seymour,
B. Schulz,
D. L. Shupe,
A. J. Smith,
M. Symeonidis,
M. Vaccari,
I. Valtchanov,
J. D. Vieira,
J. Wardlow,
C. K. Xu
[show abstract]
[hide abstract]
ABSTRACT: We present measurements of the auto- and cross-frequency power spectra of the
cosmic infrared background (CIB) at 250, 350, and 500um (1200, 860, and 600
GHz) from observations totaling ~ 70 deg^2 made with the SPIRE instrument
aboard the Herschel Space Observatory. We measure a fractional anisotropy dI /
I = 14 +- 4%, detecting signatures arising from the clustering of dusty
star-forming galaxies in both the linear (2-halo) and non-linear (1-halo)
regimes; and that the transition from the 2- to 1-halo terms, below which power
originates predominantly from multiple galaxies within dark matter halos,
occurs at k_theta ~ 0.1 - 0.12 arcmin^-1 (l ~ 2160 - 2380), from 250 to 500um.
New to this paper is clear evidence of a dependence of the Poisson and 1-halo
power on the flux-cut level of masked sources --- suggesting that some fraction
of the more luminous sources occupy more massive halos as satellites, or are
possibly close pairs. We measure the cross-correlation power spectra between
bands, finding that bands which are farthest apart are the least correlated, as
well as hints of a reduction in the correlation between bands when resolved
sources are more aggressively masked. In the second part of the paper we
attempt to interpret the measurements in the framework of the halo model. With
the aim of fitting simultaneously with one model the power spectra, number
counts, and absolute CIB level in all bands, we find that this is achievable by
invoking a luminosity-mass relationship, such that the luminosity-to-mass ratio
peaks at a particular halo mass scale and declines towards lower and higher
mass halos. Our best-fit model finds that the halo mass which is most efficient
at hosting star formation in the redshift range of peak star-forming activity,
z ~ 1-3, is log(M_peak/M_sun) ~ 12.1 +- 0.5, and that the minimum halo mass to
host infrared galaxies is log(M_min/M_sun) ~ 10.1 +- 0.6.
08/2012;
-
R. O'Brient,
P. A. R. Ade,
Z. Ahmed,
R. W. Aikin,
M. Amiri,
S. Benton,
C. Bischoff,
J. J. Bock,
J. A. Bonetti,
J. A. Brevik, [......],
G. Teply,
J. E. Tolan,
A. D. Turner,
R. S. Tucker,
A. Vieregg,
D. V. Wiebe,
P. Wilson,
C. L. Wong,
W. L. K. Wu,
K. W. Yoon
[show abstract]
[hide abstract]
ABSTRACT: Between the BICEP2 and Keck Array experiments, we have deployed over 1500
dual polarized antenna coupled bolometers to map the Cosmic Microwave
Background's polarization. We have been able to rapidly deploy these detectors
because they are completely planar with an integrated phased-array antenna.
Through our experience in these experiments, we have learned of several
challenges with this technology- specifically the beam synthesis in the
antenna- and in this paper we report on how we have modified our designs to
mitigate these challenges. In particular, we discus differential steering
errors between the polarization pairs' beam centroids due to microstrip cross
talk and gradients of penetration depth in the niobium thin films of our
millimeter wave circuits. We also discuss how we have suppressed side lobe
response with a Gaussian taper of our antenna illumination pattern. These
improvements will be used in Spider, Polar-1, and this season's retrofit of
Keck Array.
08/2012;
-
A. G. Vieregg,
P. A. R. Ade,
R. Aikin,
C. Bischoff,
J. J. Bock,
J. A. Bonetti,
K. J. Bradford,
J. A. Brevik, C. D. Dowell,
L. Duband, [......],
M. Runyan,
R. Schwarz,
C. Sheehy,
Z. Staniszewski,
R. Sudiwala,
G. Teply,
J. Tolan,
A. D. Turner,
P. Wilson,
C. L. Wong
[show abstract]
[hide abstract]
ABSTRACT: The Keck Array (SPUD) is a set of microwave polarimeters that observes from
the South Pole at degree angular scales in search of a signature of Inflation
imprinted as B-mode polarization in the Cosmic Microwave Background (CMB). The
first three Keck Array receivers were deployed during the 2010-2011 Austral
summer, followed by two new receivers in the 2011-2012 summer season,
completing the full five-receiver array. All five receivers are currently
observing at 150 GHz. The Keck Array employs the field-proven BICEP/BICEP2
strategy of using small, cold, on-axis refractive optics, providing excellent
control of systematics while maintaining a large field of view. This design
allows for full characterization of far-field optical performance using
microwave sources on the ground. We describe our efforts to characterize the
main beam shape and beam shape mismatch between co-located
orthogonally-polarized detector pairs, and discuss the implications of measured
differential beam parameters on temperature to polarization leakage in CMB
analysis.
08/2012;
-
S. Kernasovskiy,
P. A. R. Ade,
R. W. Aikin,
M. Amiri,
S. Benton,
C. Bischoff,
J. J. Bock,
J. A. Bonetti,
J. A. Brevik,
B. Burger, [......],
C. D. Sheehy,
Z. Staniszewski,
R. Sudiwala,
G. Teply,
J. E. Tolan,
A. D. Turner,
A. Vieregg,
D. V. Wiebe,
P. Wilson,
C. L. Wongg
[show abstract]
[hide abstract]
ABSTRACT: The Keck Array (SPUD) began observing the cosmic microwave background's
polarization in the winter of 2011 at the South Pole. The Keck Array follows
the success of the predecessor experiments Bicep and Bicep2, using five on-axis
refracting telescopes. These have a combined imaging array of 2500
antenna-coupled TES bolometers read with a SQUID-based time domain multiplexing
system. We will discuss the detector noise and the optimization of the readout.
The achieved sensitivity of the Keck Array is 11.5 {\mu}K_(CMB)*sqrt{s} in the
2012 configuration.
08/2012;
-
R. W. Ogburn IV,
P. A. R. Ade,
R. W. Aikin,
M. Amiri,
S. J. Benton,
C. A. Bischoff,
J. J. Bock,
J. A. Bonetti,
J. A. Brevik,
E. Bullock, [......],
Z. K. Staniszewski,
R. V. Sudiwala,
G. P. Teply,
K. Thompson,
J. E. Tolan,
A. D. Turner,
A. G. Vieregg,
D. V. Wiebe,
P. Wilson,
C. L. Wong
[show abstract]
[hide abstract]
ABSTRACT: The BICEP2 and Keck Array experiments are designed to measure the
polarization of the cosmic microwave background (CMB) on angular scales of 2-4
degrees (l=50-100). This is the region in which the B-mode signal, a signature
prediction of cosmic inflation, is expected to peak. BICEP2 was deployed to the
South Pole at the end of 2009 and is in the middle of its third year of
observing with 500 polarization-sensitive detectors at 150 GHz. The Keck Array
was deployed to the South Pole at the end of 2010, initially with three
receivers--each similar to BICEP2. An additional two receivers have been added
during the 2011-12 summer. We give an overview of the two experiments, report
on substantial gains in the sensitivity of the two experiments after
post-deployment optimization, and show preliminary maps of CMB polarization
from BICEP2.
Proc SPIE 08/2012; 8452:84521A-84521A-14.
-
Z. Staniszewski,
R. W. Aikin,
M. Amiri,
S. J. Benton,
C. Bischoff,
J. J. Bock,
J. A. Bonetti,
J. A. Brevik,
B. Burger, C. D. Dowell, [......],
R. Schwarz,
C. Sheehy,
S. Stokes,
K. L. Thompson,
G. Teply,
J. E. Tolan,
A. D. Turner,
A. G. Vieregg,
P. Wilson,
D. Wiebe
[show abstract]
[hide abstract]
ABSTRACT: The Keck array is a new multi-camera Cosmic Microwave Background (CMB) polarimeter. Each camera contains 256 polarization pairs of antenna-coupled transition edge sensor (TES) bolometers. We recently deployed three of five cameras at the geographic South Pole, and plan to deploy the final two cameras in early 2012. This new telescope is an ideal instrument to search for the primordial B-mode polarization signal imprinted in the CMB by inflationary gravitational waves. We will discuss the design of the detectors and receivers, the status of current observations, and report on progress toward upgrading the instrument with the full compliment of polarized receivers.
Journal of Low Temperature Physics 06/2012; 167(5-6):827-833. · 1.19 Impact Factor
-
Julie L. Wardlow,
Asantha Cooray,
Francesco De Bernardis,
A. Amblard,
V. Arumugam,
H. Aussel,
A. J. Baker,
M. Béthermin,
R. Blundell,
J. Bock, [......],
A. Strom,
M. Symeonidis,
M. Trichas,
M. Vaccari,
J. D. Vieira,
M. Viero,
L. Wang,
C. K. Xu,
L. Yan,
M. Zemcov
[show abstract]
[hide abstract]
ABSTRACT: We present a list of 13 candidate gravitationally lensed submillimeter
galaxies (SMGs) from 95 square degrees of the Herschel Multi-tiered
Extragalactic Survey, a surface density of 0.14\pm0.04deg^{-2}. The selected
sources have 500um flux densities (S_500) greater than 100mJy. Gravitational
lensing is confirmed by follow-up observations in 9 of the 13 systems (70%),
and the lensing status of the four remaining sources is undetermined. We also
present a supplementary sample of 29 (0.31\pm0.06deg^{-2}) gravitationally
lensed SMG candidates with S_500=80--100mJy, which are expected to contain a
higher fraction of interlopers than the primary candidates. The number counts
of the candidate lensed galaxies are consistent with a simple statistical model
of the lensing rate, which uses a foreground matter distribution, the intrinsic
SMG number counts, and an assumed SMG redshift distribution. The model predicts
that 32--74% of our S_500>100mJy candidates are strongly gravitationally lensed
(mu>2), with the brightest sources being the most robust; this is consistent
with the observational data. Our statistical model also predicts that, on
average, lensed galaxies with S_500=100mJy are magnified by factors of ~9, with
apparently brighter galaxies having progressively higher average magnification,
due to the shape of the intrinsic number counts. 65% of the sources are
expected to have intrinsic 500micron flux densities less than 30mJy. Thus,
samples of strongly gravitationally lensed SMGs, such as those presented here,
probe below the nominal Herschel detection limit at 500 micron. They are good
targets for the detailed study of the physical conditions in distant dusty,
star-forming galaxies, due to the lensing magnification, which can lead to
spatial resolutions of ~0.01" in the source plane.
05/2012;
-
HerMES Collaboration,
S. J. Oliver,
J. Bock,
B. Altieri,
A. Amblard,
V. Arumugam,
H. Aussel,
T. Babbedge,
A. Beelen,
M. Béthermin, [......],
I. Valtchanov,
J. D. Vieira,
M. Viero,
L. Vigroux,
L. Wang,
R. Ward,
J. Wardlow,
G. Wright,
C. K. Xu,
M. Zemcov
[show abstract]
[hide abstract]
ABSTRACT: The Herschel Multi-tiered Extragalactic Survey, HerMES, is a legacy program
designed to map a set of nested fields totalling ~380 deg^2. Fields range in
size from 0.01 to ~20 deg^2, using Herschel-SPIRE (at 250, 350 and 500 \mu m),
and Herschel-PACS (at 100 and 160 \mu m), with an additional wider component of
270 deg^2 with SPIRE alone. These bands cover the peak of the redshifted
thermal spectral energy distribution from interstellar dust and thus capture
the re-processed optical and ultra-violet radiation from star formation that
has been absorbed by dust, and are critical for forming a complete
multi-wavelength understanding of galaxy formation and evolution.
The survey will detect of order 100,000 galaxies at 5\sigma in some of the
best studied fields in the sky. Additionally, HerMES is closely coordinated
with the PACS Evolutionary Probe survey. Making maximum use of the full
spectrum of ancillary data, from radio to X-ray wavelengths, it is designed to:
facilitate redshift determination; rapidly identify unusual objects; and
understand the relationships between thermal emission from dust and other
processes. Scientific questions HerMES will be used to answer include: the
total infrared emission of galaxies; the evolution of the luminosity function;
the clustering properties of dusty galaxies; and the properties of populations
of galaxies which lie below the confusion limit through lensing and statistical
techniques.
This paper defines the survey observations and data products, outlines the
primary scientific goals of the HerMES team, and reviews some of the early
results.
03/2012;
-
M. Béthermin,
E. Le Floc'h,
O. Ilbert,
A. Conley,
G. Lagache,
A. Amblard,
V. Arumugam,
H. Aussel,
S. Berta,
J. Bock, [......],
M. Symeonidis,
M. Trichas,
K. E. Tugwell,
M. Vaccari,
I. Valtchanov,
J. D. Vieira,
M. Viero,
L. Wang,
C. K. Xu,
M. Zemcov
[show abstract]
[hide abstract]
ABSTRACT: ABRIGED Herschel/SPIRE has provided confusion limited maps of deep fields at
250, 350, and 500um, as part of the HerMES survey. Due to confusion, only a
small fraction of the Cosmic Infrared Background can be resolved into
individually-detected sources. Our goal is to produce deep galaxy number counts
and redshift distributions below the confusion limit, which we then use to
place strong constraints on the origins of the cosmic infrared background and
on models of galaxy evolution.
We individually extracted the bright SPIRE with a method using the positions,
the flux densities, and the redshifts of the 24um sources as a prior, and
derived the number counts and redshift distributions of the bright SPIRE
sources. For fainter SPIRE sources, we reconstructed the number counts and the
redshift distribution below the confusion limit using the deep 24um catalogs
associated with photometric redshift and information provided by the stacking
of these sources into the deep SPIRE maps. Finally, by integrating all these
counts, we studied the contribution of the galaxies to the CIB as a function of
their flux density and redshift.
Through stacking, we managed to reconstruct the source counts per redshift
slice down to ~2 mJy in the three SPIRE bands, which lies about a factor 10
below the 5sigma confusion limit. None of the pre-existing population models
are able to reproduce our results at better than 3sigma. Finally, we
extrapolate our counts to zero flux density in order to derive an estimate of
the total contribution of galaxies to the CIB, finding 10.1, 6.5, and 2.8
nW/m2/sr at 250, 350, and 500um, respectively. These values agree well with
FIRAS absolute measurements, suggesting our number counts and their
extrapolation are sufficient to explain the CIB. Finally, combining our results
with other works, we estimate the energy budget contained in the CIB between 8
and 1000um: 26 nW/m2/sr.
03/2012;
-
M J Page,
M Symeonidis,
J D Vieira,
B Altieri,
A Amblard,
V Arumugam,
H Aussel,
T Babbedge,
A Blain,
J Bock, [......],
K E Tugwell,
M Vaccari,
I Valtchanov,
M Viero,
L Vigroux,
L Wang,
R Ward,
G Wright,
C K Xu,
M Zemcov
[show abstract]
[hide abstract]
ABSTRACT: The old, red stars that constitute the bulges of galaxies, and the massive black holes at their centres, are the relics of a period in cosmic history when galaxies formed stars at remarkable rates and active galactic nuclei (AGN) shone brightly as a result of accretion onto black holes. It is widely suspected, but unproved, that the tight correlation between the mass of the black hole and the mass of the stellar bulge results from the AGN quenching the surrounding star formation as it approaches its peak luminosity. X-rays trace emission from AGN unambiguously, whereas powerful star-forming galaxies are usually dust-obscured and are brightest at infrared and submillimetre wavelengths. Here we report submillimetre and X-ray observations that show that rapid star formation was common in the host galaxies of AGN when the Universe was 2-6 billion years old, but that the most vigorous star formation is not observed around black holes above an X-ray luminosity of 10(44) ergs per second. This suppression of star formation in the host galaxy of a powerful AGN is a key prediction of models in which the AGN drives an outflow, expelling the interstellar medium of its host and transforming the galaxy's properties in a brief period of cosmic time.
Nature 01/2012; 485(7397):213-6. · 36.28 Impact Factor
-
E. M. Bierman,
T. Matsumura, C. D. Dowell,
B. G. Keating,
P. Ade,
D. Barkats,
D. Barron,
J. O. Battle,
J. J. Bock,
H. C. Chiang, [......],
E. M. Leitch,
P. V. Mason,
N. J. Miller,
H. T. Nguyen,
C. Pryke,
S. Richter,
G. M. Rocha,
C. Sheehy,
Y. D. Takahashi,
and K. W. Yoon
[show abstract]
[hide abstract]
ABSTRACT: In order to study inflationary cosmology and the Milky Way Galaxy's composition and magnetic field structure, Stokes I, Q, and U maps of the Galactic plane covering the Galactic longitude range 260° < ℓ < 340° in three atmospheric transmission windows centered on 100, 150, and 220 GHz are presented. The maps sample an optical depth 1 AV 30, and are consistent with previous characterizations of the Galactic millimeter-wave frequency spectrum and the large-scale magnetic field structure permeating the interstellar medium. The polarization angles in all three bands are generally perpendicular to those measured by starlight polarimetry as expected and show changes in the structure of the Galactic magnetic field on the scale of 60°. The frequency spectrum of degree-scale Galactic emission is plotted between 23 and 220 GHz (including WMAP data) and is fit to a two-component (synchrotron and dust) model showing that the higher frequency BICEP data are necessary to tightly constrain the amplitude and spectral index of Galactic dust. Polarized emission is detected over the entire region within two degrees of the Galactic plane, indicating the large-scale magnetic field is oriented parallel to the plane of the Galaxy. A trend of decreasing polarization fraction with increasing total intensity is observed, ruling out the simplest model of a constant Galactic magnetic field orientation along the line of sight in the Galactic plane. A generally increasing trend of polarization fraction with electromagnetic frequency is found, varying from 0.5%-1.5% at frequencies below 50 GHz to 2.5%-3.5% above 90 GHz. The effort to extend the capabilities of BICEP by installing 220 GHz band hardware is described along with analysis of the new band.
The Astrophysical Journal 10/2011; 741(2):81. · 6.02 Impact Factor
-
A J Smith,
L Wang,
S. J. Oliver,
R. Auld,
J. Bock,
D. Brisbin,
D. Burgarella,
P. Chanial,
E. Chapin,
D. L. Clements, [......],
Douglas Scott,
N. Seymour,
M. Symeonidis,
K. E. Tugwell,
M. Vaccari,
I. Valtchanov,
L. Vigroux,
R Ward,
G Wright,
M. Zemcov
[show abstract]
[hide abstract]
ABSTRACT: We describe the generation of single-band point source catalogues from
submillimetre Herschel-SPIRE observations taken as part of the Science
Demonstration Phase of the Herschel Multi-tiered Extragalactic Survey (HerMES).
Flux densities are found by means of peak-finding and the fitting of a Gaussian
point-response function. With highly-confused images, careful checks must be
made on the completeness and flux density accuracy of the detected sources.
This is done by injecting artificial sources into the images and analysing the
resulting catalogues. Measured flux densities at which 50 per cent of injected
sources result in good detections at (250, 350, 500) {\mu}m range from (11.6,
13.2, 13.1) mJy to (25.7, 27.1, 35.8) mJy, depending on the depth of the
observation (where a `good' detection is taken to be one with positional offset
less than one full-width half-maximum of the point-response function, and with
the measured flux density within a factor of 2 of the flux density of the
injected source). This paper acts as a reference for the 2010 July HerMES
public data release.
09/2011;
-
I. G. Roseboom,
R. J. Ivison,
T. R. Greve,
A. Amblard,
V. Arumugam,
R. Auld,
H. Aussel,
M. Bethermin,
A. Blain,
J. Bock, [......],
M. Vaccari,
I. Valtchanov,
J. D. Vieira,
M. P. Viero,
L. Vigroux,
J. Wardlow,
L Wang,
G Wright,
C. K. Xu,
M. Zemcov
[show abstract]
[hide abstract]
ABSTRACT: We investigate the potential of submm-mm and submm-mm-radio photometric
redshifts using a sample of mm-selected sources as seen at 250, 350 and 500
{\mu}m by the SPIRE instrument on Herschel. From a sample of 63 previously
identified mm-sources with reliable radio identifications in the GOODS-N and
Lockman Hole North fields 46 (73 per cent) are found to have detections in at
least one SPIRE band. We explore the observed submm/mm colour evolution with
redshift, finding that the colours of mm-sources are adequately described by a
modified blackbody with constant optical depth {\tau} = ({\nu}/{\nu}0)^{\beta}
where {\beta} = +1.8 and {\nu}0 = c/100 {\mu}m. We find a tight correlation
between dust temperature and IR luminosity. Using a single model of the dust
temperature and IR luminosity relation we derive photometric redshift estimates
for the 46 SPIRE detected mm-sources. Testing against the 22 sources with known
spectroscopic, or good quality optical/near-IR photometric, redshifts we find
submm/mm photometric redshifts offer a redshift accuracy of |z|/(1+z) = 0.16 (<
|z| >= 0.51). Including constraints from the radio-far IR correlation the
accuracy is improved to |z|/(1 + z) = 0.15 (< |z| >= 0.45). We estimate the
redshift distribution of mm-selected sources finding a significant excess at z
> 3 when compared to ~ 850 {\mu}m selected samples.
09/2011;
-
M Rowan-Robinson,
I ~G Roseboom,
M Vaccari,
A Amblard,
V Arumugam,
R Auld,
H Aussel,
T Babbedge,
A Blain,
J Bock, [......],
M Symeonidis,
M Trichas,
K ~E Tugwell,
I Valtchanov,
L Vigroux,
L Wang,
R Ward,
G Wright,
C ~K Xu,
M Zemcov
VizieR Online Data Catalog. 08/2011; 740:90002.
