861 research outputs found
The Cosmic Evolution of Faint Satellite Galaxies as a Test of Galaxy Formation and the Nature of Dark Matter
The standard cosmological model based on cold dark matter (CDM) predicts a
large number of subhalos for each galaxy-size halo. It is well known that
matching the subhalos to the observed properties of luminous satellites of
galaxies in the local universe poses a significant challenge to our
understanding of the astrophysics of galaxy formation. We show that the cosmic
evolution and host mass dependence of the luminosity function of satellites
provides a powerful new diagnostic to disentangle astrophysical effects from
variations in the underlying dark matter mass function. We illustrate this by
comparing the results of recent observations of satellites out to based
on Hubble Space Telescope images with the predictions of three different sets
of state-of-the art semi-analytic models with underlying CDM power spectra and
one semi-analytic model with an underlying Warm Dark Matter (WDM) power
spectrum. We find that even though CDM models provide a reasonable fit to the
local luminosity function of satellites around galaxies comparable or slightly
larger than the Milky Way, they do not reproduce the data as well for different
redshift and host galaxy stellar mass. This tension indicates that further
improvements are likely to be needed in the description of star formation if
the models are to be reconciled with the data. The WDM model matches the
observed mass dependence and redshift evolution of satellite galaxies more
closely than any of the CDM models, indicating that a modification of the
underlying power spectrum may offer an alternative solution to this tension. We
conclude by presenting predictions for the color magnitude relation of
satellite galaxies to demonstrate how future observations will be able to
further distinguish between these models and help constrain baryonic and
non-baryonic physics.Comment: Accepted for publication in ApJ, revised to incorporate referee
comment
The Missing Satellite Problem in 3D
It is widely believed that the large discrepancy between the observed number
of satellite galaxies and the predicted number of dark subhalos can be resolved
via a variety of baryonic effects which suppress star formation in low mass
halos.Supporting this hypothesis, numerous high resolution simulations with
star formation, and associated feedback have been shown to reproduce the
satellite luminosity function around Milky Way-mass simulated galaxies at
redshift zero. However, a more stringent test of these models is their ability
to simultaneously match the satellite luminosity functions of a range of host
halo masses and redshifts. In this work we measure the luminosity function of
faint (sub-Small Magellanic Cloud luminosity) satellites around hosts with
stellar masses 10.5M/M to an unprecedented
redshift of 1.5. This new measurement of the satellite luminosity function
provides powerful new constraining power; we compare these results with
predictions from four different simulations and show that although the models
perform similarly over-all, no one model reproduces the satellite luminosity
function reliably at all redshifts and host stellar masses. This result
highlights the continued need for improvement in understanding the fundamental
physics that governs satellite galaxy evolution.Comment: 9 pages, 2 figures, submitted to MNRA
A latent class analysis of parental bipolar disorder: examining associations with offspring psychopathology
Bipolar disorder (BD) is highly heterogeneous, and course variations are associated with patient outcomes. This diagnostic complexity challenges identification of patients in greatest need of intervention. Additionally, course variations have implications for offspring risk. First, latent class analysis (LCA) categorized parents with BD based on salient illness characteristics: BD type, onset age, polarity of index episode, pole of majority of episodes, rapid cycling, psychosis, anxiety comorbidity, and substance dependence. Fit indices favored three parental classes with some substantively meaningful patterns. Two classes, labeled “Earlier-Onset Bipolar-I” (EO-I) and “Earlier-Onset Bipolar-II” (EO-II), comprised parents who had a mean onset age in mid-adolescence, with EO-I primarily BD-I parents and EO-II entirely BD-II parents. The third class, labeled “Later-Onset BD” (LO) had an average onset age in adulthood. Classes also varied on probability of anxiety comorbidity, substance dependence, psychosis, rapid cycling, and pole of majority of episodes. Second, we examined rates of disorders in offspring (ages 4–33, Mage=13.46) based on parental latent class membership. Differences emerged for offspring anxiety disorders only such that offspring of EO-I and EO-II parents had higher rates, compared to offspring of LO parents, particularly for daughters. Findings may enhance understanding of BD and its nosologyThis study was funded by two Brain & Behavior Research Foundation (formerly NARSAD) Independent Investigator Awards (PI: Nierenberg), a Brain & Behavior Research Foundation Young Investigator Award (PI: Henin) generously supported in part by the SHINE Initiative, and an MGH Claflin Award (PI: Henin). We thank David A. Langer, Ph.D., Thomas M. Olino, Ph.D., and Meredith Lotz Wallace, Ph.D. for their consultation. (Brain & Behavior Research Foundation; Brain & Behavior Research Foundation Young Investigator Award; SHINE Initiative; MGH Claflin Award)Accepted manuscrip
Luminous Satellites II: Spatial Distribution, Luminosity Function and Cosmic Evolution
We infer the normalization and the radial and angular distributions of the
number density of satellites of massive galaxies
() between redshifts 0.1 and 0.8 as a function
of host stellar mass, redshift, morphology and satellite luminosity. Exploiting
the depth and resolution of the COSMOS HST images, we detect satellites up to
eight magnitudes fainter than the host galaxies and as close as 0.3 (1.4)
arcseconds (kpc). Describing the number density profile of satellite galaxies
to be a projected power law such that P(R)\propto R^{\rpower}, we find
\rpower=-1.1\pm 0.3. We find no dependency of \rpower on host stellar mass,
redshift, morphology or satellite luminosity. Satellites of early-type hosts
have angular distributions that are more flattened than the host light profile
and are aligned with its major axis. No significant average alignment is
detected for satellites of late-type hosts. The number of satellites within a
fixed magnitude contrast from a host galaxy is dependent on its stellar mass,
with more massive galaxies hosting significantly more satellites. Furthermore,
high-mass late-type hosts have significantly fewer satellites than early-type
galaxies of the same stellar mass, likely a result of environmental
differences. No significant evolution in the number of satellites per host is
detected. The cumulative luminosity function of satellites is qualitatively in
good agreement with that predicted using subhalo abundance matching techniques.
However, there are significant residual discrepancies in the absolute
normalization, suggesting that properties other than the host galaxy luminosity
or stellar mass determine the number of satellites.Comment: 23 pages, 12 figures, Accepted for publication in the Astrophysical
Journa
Probing Dark Matter with Adaptive-optics based Flux Ratio Anomalies: Photometric and Astrometric Precision
Strong gravitational lensing is a powerful probe of the distribution of
matter on sub-kpc scales. It can be used to test the existence of completely
dark subhalos surrounding galaxies, as predicted by the standard cold dark
matter model, or to test alternative dark matter models. The constraining power
of the method depends strongly on photometric and astrometric precision and
accuracy. We simulate and quantify the capabilities of upcoming adaptive optics
systems and advanced instruments on ground-based telescopes, focusing as an
illustration on the Keck Telescope (OSIRIS + KAPA, LIGER + KAPA) and the Thirty
Meter Telescope (TMT; IRIS + NFIRAOS). We show that these new systems will
achieve dramatic improvements over current ones in both photometric and
astrometric precision. Narrow line flux ratio errors below , and
submilliarcsecond astrometric precision will be attainable for typical
quadruply imaged quasars. With TMT, the exposure times required will be of
order a few minutes per system, enabling the follow-up of 100-1000 systems
expected to be discovered by the Rubin, Euclid, and Roman Telescopes.Comment: 14 pages, 10 figure
Transdiagnostic treatment of bipolar disorder and comorbid anxiety using the Unified Protocol for Emotional Disorders: A pilot feasibility and acceptability trial
BACKGROUND
Comorbid anxiety in bipolar disorder (BD) is associated with greater illness severity, reduced treatment response, and greater impairment. Treating anxiety in the context of BD is crucial for improving illness course and outcomes. The current study examined the feasibility, acceptability and preliminary efficacy of the Unified Protocol (UP), a transdiagnostic cognitive behavioral therapy, as an adjunctive treatment to pharmacotherapy for BD and comorbid anxiety disorders.
METHODS
Twenty-nine patients with BD and at least one comorbid anxiety disorder were randomized to pharmacotherapy treatment-as-usual (TAU) or TAU with 18 sessions of the UP (UP+TAU). All patients completed assessments every four weeks to track symptoms, functioning, emotion regulation and temperament. Linear mixed-model regressions were conducted to track symptom changes over time and to examine the relationship between emotion-related variables and treatment response.
RESULTS
Satisfaction ratings were equivalent for both treatment groups. Patients in the UP+TAU group evidenced significantly greater reductions over time in anxiety and depression symptoms (Cohen's d's>0.80). Baseline levels of neuroticism, perceived affective control, and emotion regulation ability predicted magnitude of symptom change for the UP+TAU group only. Greater change in perceived control of emotions and emotion regulation skills predicted greater change in anxiety related symptoms.
LIMITATIONS
This was a pilot feasibility and acceptability trial; results should be interpreted with caution.
CONCLUSIONS
Treatment with the UP+TAU was rated high in patient satisfaction, and resulted in significantly greater improvement on indices of anxiety and depression relative to TAU. This suggests that the UP may be a feasible treatment approach for BD with comorbid anxiety.This work was supported by a Postdoctoral National Research Service Award from the National Institutes of Health [F32 MH098490] to K. Ellard. (F32 MH098490 - Postdoctoral National Research Service Award from the National Institutes of Health)Accepted manuscrip
Probing dark matter substructure in the gravitational lens HE0435-1223 with the WFC3 grism
Strong gravitational lensing provides a powerful test of Cold Dark Matter
(CDM) as it enables the detection and mass measurement of low mass haloes even
if they do not contain baryons. Compact lensed sources such as Active Galactic
Nuclei (AGN) are particularly sensitive to perturbing subhalos, but their use
as a test of CDM has been limited by the small number of systems which have
significant radio emission which is extended enough avoid significant lensing
by stars in the plane of the lens galaxy, and red enough to be minimally
affected by differential dust extinction. Narrow-line emission is a promising
alternative as it is also extended and, unlike radio, detectable in virtually
all optically selected AGN lenses. We present first results from a WFC3 grism
narrow-line survey of lensed quasars, for the quadruply lensed AGN HE0435-1223.
Using a forward modelling pipeline which enables us to robustly account for
spatial blending, we measure the [OIII] 5007 \AA~ flux ratios of the four
images. We find that the [OIII] fluxes and positions are well fit by a simple
smooth mass model for the main lens. Our data rule out a NFW perturber projected within 1\farcs0 (0\farcs1)
arcseconds of each of the lensed images, where is the perturber mass
within its central 600 pc. The non-detection is broadly consistent with the
expectations of CDM for a single system. The sensitivity achieved
demonstrates that powerful limits on the nature of dark matter can be obtained
with the analysis of narrow-line lenses.Comment: Accepted for publication in MNRAS, 15 pages, 8 figure
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Nutrition, Exercise, and Wellness Treatment in bipolar disorder: proof of concept for a consolidated intervention
Background: This pilot study examines the proof of concept of a consolidated Nutrition, Exercise, and Wellness Treatment (NEW Tx) for overweight individuals with bipolar disorder. Findings: Five participants completed NEW Tx, a 20-week individual cognitive behavioral therapy-based treatment comprising three modules: Nutrition teaches appropriate serving sizes and balanced diet; Exercise emphasizes increasing weekly physical activity; Wellness focuses on skills for healthy decision-making. Participants attended most sessions and reported high satisfaction with the treatment. Participants’ weight, cholesterol and trigyclerides decreased over the study duration as well as number of daily calories and sugar intake. We found that weekly exercise duration more than tripled over the study duration and depressive symptoms and functioning have improved. Conclusions: These results offer proof of concept that consolidated NEW Tx is feasible and acceptable and has the potential to improve nutrition, exercise, wellness, and mood symptoms in bipolar disorder. Future iterations of NEW Tx will reflect the strengths and lessons learned from this study
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