2,318 research outputs found
Examining collusion and voting biases between countries during the Eurovision song contest since 1957
The Eurovision Song Contest (ESC) is an annual event which attracts millions
of viewers. It is an interesting activity to examine since the participants of
the competition represent a particular country's musical performance that will
be awarded a set of scores from other participating countries based upon a
quality assessment of a performance. There is a question of whether the
countries will vote exclusively according to the artistic merit of the song, or
if the vote will be a public signal of national support for another country.
Since the competition aims to bring people together, any consistent biases in
the awarding of scores would defeat the purpose of the celebration of
expression and this has attracted researchers to investigate the supporting
evidence for biases. This paper builds upon an approach which produces a set of
random samples from an unbiased distribution of score allocation, and extends
the methodology to use the full set of years of the competition's life span
which has seen fundamental changes to the voting schemes adopted.
By building up networks from statistically significant edge sets of vote
allocations during a set of years, the results display a plausible network for
the origins of the culture anchors for the preferences of the awarded votes.
With 60 years of data, the results support the hypothesis of regional collusion
and biases arising from proximity, culture and other irrelevant factors in
regards to the music which that alone is intended to affect the judgment of the
contest.Comment: to be published in JASS
Early social rearing, the V1A arginine vasopressin receptor genotype, and autistic traits in chimpanzees
Previous studies found associations between autism-related phenotypes and both rearing and V1A arginine vasopressin receptor (AVPR1A) genotypes. We tested whether these exposures as well as their interaction were associated with autism-related phenotypes in 121 laboratory-housed chimpanzees. We used expert-derived weights to obtain autism scores from ratings on the 43-item Chimpanzee Personality Questionnaire; higher scores indicated more autistic-like traits. The first model included fixed effects for sex, age, and rearing, and a random effect that addressed the relatedness of subjects. The second model was the same except that it also included the rearing × AVPR1A genotype interaction as a fixed effect. Both models indicated that the phenotype was moderately heritable and that chimpanzees reared by their mothers had lower scores on the scale. The effect of genotype in both models indicated that chimpanzees with an indel deletion had higher scores on the scale, although the credible interval included zero. Moreover, the rearing × genotype interaction in the second model indicated that chimpanzees who possessed the non-deletion genotype and who were reared by their mother were at even greater risk. The credible interval for this effect did not include zero, but fit statistics indicated that the model without the interaction was marginally better, and the interaction was in the opposite direction than we expected based on previous work. These findings highlight the importance of rearing effects in the typical social development of our closet-living nonhuman relative
The Formation of High Redshift Submillimeter Galaxies
We describe a model for the formation of \zsim 2 Submillimeter Galaxies
(SMGs) which simultaneously accounts for both average and bright SMGs while
providing a reasonable match to their mean observed spectral energy
distributions (SEDs). By coupling hydrodynamic simulations of galaxy mergers
with the high resolution 3D polychromatic radiative transfer code Sunrise, we
find that a mass sequence of merger models which use observational constraints
as physical input naturally yield objects which exhibit black hole, bulge, and
H2 gas masses similar to those observed in SMGs. The dominant drivers behind
the 850 micron flux are the masses of the merging galaxies and the stellar
birthcloud covering fraction. The most luminous (S850 ~ 15 mJy) sources are
recovered by ~10^13 Msun 1:1 major mergers with a birthcloud covering fraction
close to unity, whereas more average SMGs ~5-7 mJy) may be formed in lower mass
halos ~5x10^12 Msun. These models demonstrate the need for high spatial
resolution hydrodynamic and radiative transfer simulations in matching both the
most luminous sources as well as the full SEDs of SMGs. While these models
suggest a natural formation mechanism for SMGs, they do not attempt to match
cosmological statistics of galaxy populations; future efforts along this line
will help ascertain the robustness of these models.Comment: MNRAS Accepted; Revised version includes expanded discussion of
simulated radio properties of SMG
T-duality and Differential K-Theory
We give a precise formulation of T-duality for Ramond-Ramond fields. This
gives a canonical isomorphism between the "geometrically invariant" subgroups
of the twisted differential K-theory of certain principal torus bundles. Our
result combines topological T-duality with the Buscher rules found in physics.Comment: 23 pages, typos corrected, submitted to Comm.Math.Phy
Deep, ultra-high-resolution radio imaging of submillimetre galaxies using Very Long Baseline Interferometry
We present continent-scale VLBI - obtained with the European VLBI Network
(EVN) at a wavelength of 18cm - of six distant, luminous submm-selected
galaxies (SMGs). Our images have a synthesized beam width of ~30 milliarcsec
FWHM - three orders of magnitude smaller in area than the highest resolution
VLA imaging at this wavelength - and are capable of separating radio emission
from ultra-compact radio cores (associated with active super-massive black
holes - SMBHs) from that due to starburst activity. Despite targeting compact
sources - as judged by earlier observations with the VLA and MERLIN - we
identify ultra-compact cores in only two of our targets. This suggests that the
radio emission from SMGs is produced primarily on larger scales than those
probed by the EVN, and therefore is generated by star formation rather than an
AGN - a result consistent with other methods used to identify the presence of
SMBHs in these systems.Comment: MNRAS, in pres
Mergers, AGN, and 'Normal' Galaxies: Contributions to the Distribution of Star Formation Rates and Infrared Luminosity Functions
We use a novel method to predict the contribution of normal star-forming
galaxies, merger-induced bursts, and obscured AGN, to IR luminosity functions
(LFs) and global SFR densities. We use empirical halo occupation constraints to
populate halos with galaxies and determine the distribution of normal and
merging galaxies. Each system can then be associated with high-resolution
hydrodynamic simulations. We predict the distribution of observed luminosities
and SFRs, from different galaxy classes, as a function of redshift from z=0-6.
We provide fitting functions for the predicted LFs, quantify the uncertainties,
and compare with observations. At all redshifts, 'normal' galaxies dominate the
LF at moderate luminosities ~L* (the 'knee'). Merger-induced bursts
increasingly dominate at L>>L*; at the most extreme luminosities, AGN are
important. However, all populations increase in luminosity at higher redshifts,
owing to increasing gas fractions. Thus the 'transition' between normal and
merger-dominated sources increases from the LIRG-ULIRG threshold at z~0 to
bright Hyper-LIRG thresholds at z~2. The transition to dominance by obscured
AGN evolves similarly, at factor of several higher L_IR. At all redshifts,
non-merging systems dominate the total luminosity/SFR density, with
merger-induced bursts constituting ~5-10% and AGN ~1-5%. Bursts contribute
little to scatter in the SFR-stellar mass relation. In fact, many systems
identified as 'ongoing' mergers will be forming stars in their 'normal'
(non-burst) mode. Counting this as 'merger-induced' star formation leads to a
stronger apparent redshift evolution in the contribution of mergers to the SFR
density.Comment: 16 pages, 9 figures (+appendices), accepted to MNRAS. A routine to
return the galaxy merger rates discussed here is available at
http://www.cfa.harvard.edu/~phopkins/Site/mergercalc.htm
A Physical Model for z~2 Dust Obscured Galaxies
We present a physical model for the origin of z~2 Dust-Obscured Galaxies
(DOGs), a class of high-redshift ULIRGs selected at 24 micron which are
particularly optically faint (24/R>1000). By combining N-body/SPH simulations
of high redshift galaxy evolution with 3D polychromatic dust radiative transfer
models, we find that luminous DOGs (with F24 > 0.3 mJy at z~2 are well-modeled
as extreme gas-rich mergers in massive (~5x10^12-10^13 Msun) halos, with
elevated star formation rates (~500-1000 Msun/yr) and/or significant AGN growth
(Mdot > 0.5 Msun/yr), whereas less luminous DOGs are more diverse in nature. At
final coalescence, merger-driven DOGs transition from being starburst dominated
to AGN dominated, evolving from a "bump" to a power-law shaped mid-IR (IRAC)
spectral energy distribution (SED). After the DOG phase, the galaxy settles
back to exhibiting a "bump" SED with bluer colors and lower star formation
rates. While canonically power-law galaxies are associated with being
AGN-dominated, we find that the power-law mid-IR SED can owe both to direct AGN
contribution, as well as to a heavily dust obscured stellar bump at times that
the galaxy is starburst dominated. Thus power-law galaxies can be either
starburst or AGN dominated. Less luminous DOGs can be well-represented either
by mergers, or by massive ($M_{\rm baryon} ~5x10^11 Msun) secularly evolving
gas-rich disc galaxies (with SFR > 50 Msun/yr). By utilising similar models as
those employed in the SMG formation study of Narayanan et al. (2010), we
investigate the connection between DOGs and SMGs. We find that the most heavily
star-forming merger driven DOGs can be selected as Submillimetre Galaxies
(SMGs), while both merger-driven and secularly evolving DOGs typically satisfy
the BzK selection criteria.Comment: Accepted by MNRAS; major changes include better description of
dependency on ISM specification and updated models allowing dust to evolve
with metallicity
Obscured GOODS AGN and Their Host Galaxies at z < 1.25: The Slow Black Hole Growth Phase
We compute black hole masses and bolometric luminosities for 87 obscured AGN
in the redshift range 0.25 < z < 1.25, selected from the GOODS deep
multi-wavelength survey fields via their X-ray emission. We fit the optical
images and obtain morphological parameters for the host galaxy, separating the
galaxy from its central point source, thereby obtaining a four-band optical SED
for each active nucleus. We calculate bolometric luminosities for these AGN by
reddening a normalized mean SED of GOODS broad-line AGN to match the observed
central point-source SED of each obscured AGN. This estimate of Lbol has a
smaller spread than simple bolometric corrections to the X-ray luminosity or
direct integration of the observed multi-wavelength SED, suggesting it is a
better measure. We estimate central black hole masses from the bulge
luminosities. The black hole masses span a wide range, 7 x 10^6 M_sun to 6 x
10^9 M_sun; the median black hole mass is 5 x 10^8 M_sun. The majority of these
AGN have L/L_Edd < 0.01, and we detect no significant evolution of the mean
Eddington ratio to z = 1.25. This implies that the bulk of black hole growth in
these obscured AGN must have occurred at z > 1 and that we are observing these
AGN in a slow- or no-growth state.Comment: Accepted to ApJ; 17 pages, 10 figures, 2 tables; Updated version has
1 corrected referenc
The physical scale of the far-infrared emission in the most luminous submillimetre galaxies II: evidence for merger-driven star formation
We present high-resolution 345 GHz interferometric observations of two
extreme luminous (L_{IR}>10^{13} L_sun), submillimetre-selected galaxies (SMGs)
in the COSMOS field with the Submillimeter Array (SMA). Both targets were
previously detected as unresolved point-sources by the SMA in its compact
configuration, also at 345 GHz. These new data, which provide a factor of ~3
improvement in resolution, allow us to measure the physical scale of the
far-infrared in the submillimetre directly. The visibility functions of both
targets show significant evidence for structure on 0.5-1 arcsec scales, which
at z=1.5 translates into a physical scale of 5-8 kpc. Our results are
consistent with the angular and physical scales of two comparably luminous
objects with high-resolution SMA followup, as well as radio continuum and CO
sizes. These relatively compact sizes (<5-10 kpc) argue strongly for
merger-driven starbursts, rather than extended gas-rich disks, as the preferred
channel for forming SMGs. For the most luminous objects, the derived sizes may
also have important physical consequences; under a series of simplifying
assumptions, we find that these two objects in particular are forming stars
close to or at the Eddington limit for a starburst.Comment: 9 pages, 3 Figures, submitted to MNRA
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