Day 1375

Tuesday.

1802.09021
Instrumental effects in BRITE photometry
Pigulski, et al

Instrumental effects from BRITE satellites: first fleet of nano-satellites aimed at doing space photometry in the visual domain; host 3-cm refractor wide-field (24 deg FoV) and uncooled CCD detectors.  Due to low mass (~7kg); not perfectly stabilized.  (1) Correlations with position, CCD temperature and other parameters (2) Saturation and non-linearities (3) CTI (4) stray light (5) tracker grinding.


1802.09014
Reconstruction of convergence power spectrum from SNLS weak lensing data
Mitra, Pal, Pal

Estimate the lensing convergence PS from SNe magnification data using real space correlation function technique.  For the analysis, utilized 296 SNe from 5yr Supernovae Legacy Survey in the WL limit  Data used consists of measurements from 4 different patches, each of them covering almost 1 sq deg of the sky, merged together.  Demonstrate that it is quite possible to have a good estimate of the convergence PS from this data.  The primary intention is to extract meaningful informations from SNLS WL data and to demonstrate how the power spectrum for convergence can be reconstructed therefrom, without going into the nitty-gritty of errors, although dome errors analysis has been done.

Day 1374

Monday.

1802.08263
Measuring the scale-dependence of intrinsic alignments using multiple shear estimates
Leonard, Mandelbaum

Present a new method for measuring the scale-dependence of the IA contamination to the gglensing signal, which takes advantage of multiple shear estimation methods applied to the same source galaxy sample.  By exploiting the resulting correlation of both shape noise and cosmic variance, the method can provide an increase in the S/N of the measured IA signal as compared to methods which rely on the difference of the lensing signal from multiple photometric redshift bins.  For a galaxy-galaxy lensing measurement which uses LSST sources and DESI lenses, the S/N on the IA signal from the method is predicted to improve by a factor of ~2 relative to the method of Blazek+2012, for pairs of shear estimates which yield substantially different measured IA amplitudes and highly correlated shape noise terms.  Show that statistical error necessarily dominates the measurement of IA using this method.  Also consider a physically motivated extension of the Blazek+2012 method which assumes that all nearby galaxy pairs rather than only excess pairs, are subject to IA.  In this case, the S/N of the method of Blazek+2012 is improved.

Day 1373

Friday.

1802.07774
Looking at cosmic near-infrared background radiation anisotropies
Kashlinsky, et al

The cosmic infrared background (CIB) contains emissions accumulated over the entire history of the Universe, including from objects inaccessible to individual telescopic studies.  The near-IR (~1-10 mic) part of the CIB, and its fluctuations, reflects emissions from nucleosynthetic sources and gravitationally accreting BHs.  If known galaxies are removed to sufficient depths the source-subtracted CIB fluctuations at near-IR can reveal sources present in the first-stars-era and possibly new stellar populations at more recent times.  This review discusses the recent progress in this newly emerging field which identified, with new data and methodology, significant source-subtracted CIB fluctuations substantially in excess of what can be produced by remaining known galaxies.  The CIB fluctuations further appear coherent with unresolved comic X-ray background (CXB) indicating a very high fraction of BHs among the new sources producing the CIB fluctuations.  These observations have led to intensive theoretical efforts to explain the measurements and their properties.  While current experimental configurations have limitations in decisively probing these theories, their potentially remarkable implications will be tested in the upcoming CIB measurements with the ESA's Euclid DE mission.  Describe the goals and methodologies of LIBRAE (Looking at Infrared Background Radiation with Euclid), a NASA-selected project for CIB science with Euclid, which has the potential for transforming the field into a new area of precision cosmology.

Day 1372

Thursday.

1802.06914
A binary offset effect in CCD readout and its impact on astronomical data
Boone, Aldering, ... Perlmutter, et al

A discovery of an anomalous behavior of CCD readout electronics that affects their use in many astronomical applications.  An offset in the digitization of the CCD output voltage that depends on the binary encoding of one pixel is added to pixels that are read out one, two and/or three pixels later.  One result of this effect is the introduction of a differential offset in the background when comparing regions with and without flux from science targets.  Conventional data reduction methods do not correct for this offset.  Find this effect in 16 of 22 instruments investigated, covering a variety of telescope and many different front-end electronics systems.  The affected instruments include LRIS and DEIMOS on the Keck telescopes, WFC3-UVIS and STIS on HST, MegaCam on CFHT, SNIFS on the UH88 telescope, GMOS on the Gemini telescopes, HSC on Subaru, and FORS on VLT.  The amplitude of the introduced offset is up to 4.5 ADU per pixel, and it is not directly proportional to the measured ADU level.  Developed a model that can be used to detect this "binary offset effect" in data and correct for it.  Understanding how data are affected and applying a correction for the effect is essential for precise astronomical measurements.


1802.07708
A radial measurement of the galaxy tidal alignment magnitude with BOSS data
Martens, Hirata, Ross, Fang

The anisotropy of galaxy clustering in redshift space has long been used to probe the rate of growth of cosmological perturbations.  However, if galaxies are aligned by large-scale tidal fields, then a sample with an orientation-dependent selection effect has an additional anisotropy imprinted onto its correlation function.  Use the LOWZ and CMASS catalogs of SDSS-III BOSS DR12 to divide galaxies into two sub-samples based on their offset from the Fundamental Plane, which should be correlated with orientation.   These sub-samples must trace the same underlying cosmology, but have opposite orientation-dependent selection effects.  Measure the clustering parameters of each sub-sample and compare them in order to calculate the dimensionless parameter B, a measure of how strongly galaxies are aligned by gravitational tidal fields.  Found that for CMASS (LOWZ), the measured B was -0.024±0.015 (-0.030±0.016).  This result can be compared to the theoretical predictions of Hirata 2009, who argued that since galaxy formation physics does not depend on the direction of the observer, the same intrinsic alignment parameters that describe galaxy-ellipticity correlations should also describe intrinsic alignments in the radial direction.  Find that the ratio of observed to theoretical values is 0.15±0.32 (0.77±0.41) for CMASS (LOWZ).  Combine the results to obtain a total Obs/Theory = 0.61±0.26.  This measurement constitutes evidence (between 2 and 3 sigma) for radial intrinsic alignments, and is consistent with theoretical expectations (<2 sigma difference).

Day 1371

Monday.  Tuesday.  Wednesday.

1802.06794
Jupiter Analogues orbit stars with an average metallicity close to that of the Sun
Buchhave, et al

Jupiter played an important role in determining the structure and configuration of the Solar System.  Whereas hot-Jupiter type exoplanets preferentially form around metal-rich stars, the conditions required for the formation of planets with masses, orbits and eccentricities comparable to Jupiter (Jupiter analogues) are unknown.  Using spectroscopic metallicities, show that stars hosting Jupiter analogues have an average metallicity close to solar, in contrast to their hot-Jupiter and eccentric cool Jupiter counterparts, which orbit stars with super-solar metallicities.  Furthermore, the eccentricities of Jupiter analogues increase with host star metallicity, suggesting that planet-planet scatterings producing highly eccentric cool Jupiters could be more common in metal-rich environments.  To investigate a possible explanation for these metallicity trends, compare the observations to numerical simulations, which indicate that metal-rich stars typically form multiple Jupiters, leading to planet-planet interactions and, hence, a prevalence of either eccentric cool Jupiters or hot-Jupiters with circularized orbits.  Although the samples are small and exhibit variations in their metallicities, suggesting that numerous processes other than metallicity affect the formation of planetary systems, the data in hand suggests that Jupiter analogues and terrestrial-sized planets form around stars with average metallicities close to solar, whereas high metallicity systems preferentially host eccentric cool Jupitor or hot-Jupiters, indicating higher metallicity systems may not be favorable for the formation of planetary systems akin to the Solar System.


1802.07036
The habitability of our Evolving Galaxy
Gowanlock, Morrison

The notion of Galactic Habitable Zone (GHZ), or regions of the MW galaxy that preferentially maintain the conditions to sustain complex life, has recently gained attention due to the detection of numerous exoplanets and advances made in understanding habitability on the Earth and other environments.  Discuss what a habitable environment means on large spatial and temporal scales, which necessarily requires an approximated definition of habitability to make an assessment of the astrophysical conditions that may sustain complex life.  Discuss a few key exoplanet findings that directly relate to estimating the distribution of Earth-size planets in the Milky Way.  With a broad notion of habitability defined and major observable properties of the MW described, compare selected literature on the GHZ and postulate why the models yield differing predictions of the most habitable regions at the present day, which include: (1) the majority of the galactic disk; (2) an annular ring between 7-9 kpc, and (3) the galactic outskirts.  Briefly discuss the habitability of other galaxies as influenced by these studies.  Note that the dangers to biospheres in the Galaxy taken into account in these studies may be incomplete and discuss the possible role of Gamma-Ray Bursts and other dangers to life n the MW.  Speculate how changing astrophysical properties may affect the GHZ over time, including before the Earth formed, and describe how new observations and other related research may fit into the bigger picture of the habitability of the Galaxy.

Day 1370

Tuesday.  Wednesday, Thursday, Friday.

1802.03403
Gauge-invariant formalism of cosmological weak lensing
Yoo, Grimm, Mitsou, Amara, Refregier

Present the gauge-invariant formalism of cosmo WL, accounting for all the relativistic effects due to the scalar, vector, and tensor perturbations at the linear order.  While the light propagation is fully described by the geodesic equation, the relation of the photon wave vector to the physical quantities requires the specification of the frames, where they are defined.  By constructing the local tetrad bases at the observer and the source positions, clarify the relation of the WL observables such as convergence, the shear, and the rotation to the physical size and shape defined in the source rest-frame and the observed angle and redshift measured in the observer rest-frame.  Compared to the standard lensing formalism, additional relativistic effects contribute to all the lensing observables.  Explicitly verify the gauge-invariance of the lensing observables and compare the results to previous work.  In particular, demonstrate that even in the presence of the vector and tensor perturbations, the physical rotation of the lensing observables vanishes at the linear order, while the tetrad basis rotates along the light propagation compared to a FRW coordinate.  Though the latter is often used as a probe of primordial gravitational waves, the rotation of the tetrad basis is indeed not a physical observable.  Further clarify its relation to the E-B decomposition in WL.  The formalism provides a transparent and comprehensive perspective of cosmological WL.


1802.03474
Skyglow changes over Tucson, Arizona, resulting from a municipal LED street lighting conversion
Barentine, et al

The transition from earlier lighting technologies to white light-emitting diodes (LEDs) is a significant change in the use of artificial light at night.  LEDs emit considerably more short-wavelength light into the environment than earlier technologies on a per-lumen basis.  Radiative transfer models predict increased skyglow over cities transitioning to LED unless the total lumen output of a new lighting systems is reduced.  The City of Tucson, AZ (U.S.), recently converted its municipal street lighting system from a mixture of fully shielded high- and low-pressure sodium (HPS/LPS) luminaries to fully shielded 3000K white LED luminaries.  The lighting design intended to minimize increases to sky glow in order to protect the sites of nearby astronomical observatories without compromising public safety.  This involved the migration of over 445 million fully shielded HPS/LPS lumens to roughly 142 million fully shielded 3000K white LED lumens and an expected concomitant reduction in the amount of visual skyglow over Tucson.  SkyGlow Simulator models predict skyglow decreases in the order of 10-20% depending on whether fully shielded or partly shielded lights are in use.  Tested this prediction using visual night sky brightness estimates and luminance-calibrated, panchromatic all-sky imagery at 15 locations in and near the city.  Data were obtained in 2014, before the LED conversion began, and in mid-2017 after approximately 95% of ~18,000 luminaries was converted.  Skyglow differed marginally, and in all cases with valid data changed by <±20%.  Over the same period, the city's upward-directed optical radiance detected from Earth orbit decreased by approximately 7%.  While these results are not conclusive, they suggest that LED conversions paired with dimming can reduce skyglow over cities.


1802.03609
The strong gravitational lens finding challenge
Metcalf, et al

Large scale imaging surveys will increase the number of galaxy-scale strong lensing candidates by maybe 3 orders of magnitudes beyond the number known today.  Finding these rare objects will require picking them out of at least tens of millions of images and deriving scientific results from them will require quantifying the efficiency and bias of any search method.  To achieve these objectives automated methods must be developed.  Because gravitational lenses are rare objects, reducing false positive will be particularly important.  Present a description and results of an open gravitational lens finding challenge.  Participants were asked to classify 100,000 candidate objects as to whether they were gravitational lenses or not with the goal of developing better automated methods for finding lenses in large data sets.  A variety of methods were used including visual inspection, arc and ring finders, support vector machines (SVM) and convolutional neural networks (CNN).  Find that many of the methods will be easily fast enough to analyse the anticipated data flow.  In test data, several methods are able to identify upwards of half the lenses after applying some thresholds on the lens characteristics such as lensed image brightness, size or contrast with the lens galaxy without making a single cals-positive identification.  This is significantly better than direct inspection by humans was able to do.


1802.04271
Machine learning cosmological structure formation
Lucie-Smith, Peiris, Pnotzen, Lochner

Train a machine learning algorithm to learn cosmological structure formation from N-body simulations.  The algorithm infers the relationship between the initial conditions and the final dark matter haloes, without the need to introduce approximate halo collapse models.  Gain insights into the physics driving halo formation by evaluating the predictive performance of the algorithm when provided when different types of information about the local environment around DM particles.  The algorithm learns to predict whether or not DM particles will end up in haloes of a given mass range, based on spherical over densities.  Show that the resulting predictions match those of spherical collapse approximations such as extended Press-Schechter theory.  Additional information on the shape of the local gravitational potential is not able to improve halo collapse predictions; the linear density field contains sufficient information for the algorithm to also reproduce ellipsoidal collapse predictions based on the Sheth-Tormen model.  Investigate the algorithm's performance in terms of halo mass and radial position and perform blind analyses on independent initial conditions realizations to demonstrate the generality of the results.


1802.04379
Search for Neutrinos in Super-Kamiokande associated with the GW170817 neutron-star merger
Abe, et al

Calculated 90% CL upper limits on the neutrino fluency for GW170817.  From the upward-going-muon events in the energy region above 1.6 GeV, the neutrino fluency limit is 16.0±0.7 (21.3±1.1) cm^{-2} for muon neutrinos (muon antineutrinos), with an error range of ±5deg around the zenith angle of NGC4993, and the energy spectrum is under the assumption of an index of -2.  The fluency limit for neutrino energies less than 100 MeV, for which the emission mechanism would be different than for higher-energy neutrinos, is also calculated.  It is 6.6e7 cm^-2 for anti-electron neutrinos under the assumption of a Fermi-Direc spectrum with average energy of 20 MeV.


1802.04462
Robustness of the covariance matrix for galaxy clustering measurements
Baumgarten, Chuang

Present a study on the robustness of the covariance matrix estimation for galaxy clustering measurements depending on the cosmological parameters and galaxy bias.  To this end, produced 9000 galaxy mock catalogues relying on the effective Zel'dovich approximation implemented in the EZmocks computer code, using different input cosmological models and bias parameters.  The reference catalogue has also been produced with this code making the study insensitive to the approximation at least on a relative-qualitative level.  The findings indicate that the covariance matrix is insensitive to the input power spectrum (including sigma8), as long as the 2- and 3-point galaxy clustering measurements agree with the given data.  In fact, the covariance matrix shows a bias at small scales (r<~40 Mpc/h) when the chosen galaxy bias parameters yield a 3-pt statistics, which is not compatible with the reference one within the error bars, even though the 2-pt statistics agree within 1%.  Nevertheless, the error becomes negligible at large scales making the covariance matrix still reliable for data analysis using only measurements in that regime (e.g., measuring baryons acoustic oscillations).  High precision in cosmological parameter estimation is expected for covariance matrices extracted from mock galaxy catalogues which take accurately into account both the 2- and the 3-pt statistics.  This is independent of whether this is achieved by using the right cosmology and galaxy bias (which are not a priori known) or just any combination of both fitting the net observed galaxy clustering.


1802.04718
The random walk of cars and their collision probabilities with planets
Rein, Tamayo, Vokrouhlicky

On Feb. 6th, 2018, SpaceX launched a Tesla Roadster on a Mars crossing orbit.  Perform N-body simulations to determine the fate of the object over the next several million years, und the relevant perturbations acting on the orbit.  The orbital evolution is initially dominated by close encounters with the Earth.  The first close encounter with the Earth will occur in 2091.  The repeated encounters lead to a random walk that eventually causes close encounters with other terrestrial planets and the Sun.  Long-term interactions become highly sensitive to the initial conditions after several such close encounters.  By running a large ensemble of simulations with slightly perturbed initial conditions, estimate the probability of a collision with Earth and Venus over the next one million years to be 6% and 2.5%, respectively.  Estimate the dynamical lifetime of the Tesla to be a few tens of millions of years.


1802.04891
Modified Gravity (MOG) and its test on galaxy clusters
Nieuwenhuizen, Morandi, Limousin

The MOdified Gravity (MOG) theory of J. Moffat assumes a massive vector particle which causes a repulsive contribution to the tensor gravitation.  For the galaxy cluster A1689 new data for the X-ray gas and the strong lensing properties are presented.  Fits to MOG are possible by adjusting the galaxy density profile.  However, this appears to work as an effective DM component, posing a serious problem for MOG.  New gas and strong lensing data for the cluster A1835 support these conclusions and point at a tendency of the gas-alone to overestimate the lensing effects in MOG theory.


1802.04816
Cosmic curvature tested directly from observations
Denissenya, Linder, Shafieloo

Cosmic spatial curvature is a fundamental geometric quantity of the Universe.  Investigate a model independent, geometric approach to measure spatial curvature directly from observations, without any derivatives of data.  This employs strong lensing time delays and supernova distance measurements to measure the curvature itself, rather than just testing consistency with flatness.  Define 2 curvature estimators, with differing error propagation characteristics, that can crosscheck each other, and also show how they can be used to map the curvature in z slices, to test constancy of curvature as required by the Robertson-Walker metric.  Simulating realizations of redshift distributions and distance measurements of lenses and sources, estimate uncertainties on the curvature enabled by next generation measurements.  The results indicate that the model independent methods, using only geometry without assuming forms for the energy density constituents, can determine the curvature at the ~6e-3 level.


1802.05089
Gravitational lensing of gravitational waves: a statistical perspective
Li, Mao, Zhao, Lu

In this paper, study the strong GL of gravitational waves (GWs) from a statistical perspective, with particular focus on the high frequency GWs from stellar binary BH coalescences.  These are most promising targets for ground-based detectors such as aLIGO and the proposed Einstein Telescope (ET) and can be safely treated under the geometrical optics limit for GW propagation.  Performa a thorough calculation of the lensing rate, by taking account of effects caused by the ellipticity of lensing galaxies, lens environments, and magnification bars.  Find that in certain GW source rate scenarios, should be able to observed strongly lensed GW events once per year (~1/yr) in the aLIGO survey at its design sensitivity; for the proposed ET survey, the rate could be as high as ~80/yr.  These results depend on the estimate of GW source abundance, and hence can be correspondingly modified with an improvement in the understanding of the merger rate of stellar binary BHs.  Also compute the fraction of 4-image lens systems in each survey, predicting it to be ~30% for the aLIGO survey and ~6% for the ET survey.  Finally, evaluate the possibility of missing some images due to the finite survey duration, by presenting the probability distribution of lensing time delays.  Predict that this selection bias will be insignificant in future GW surveys, as most of the lens systems (~90%) will have time delays less than ~1 month which will be far shorter than survey durations.


1802.05257
Dark Energy Survey Year 1 Results: methodology and projection for joint analysis of galaxy clustering, galaxy lensing, and CMB lensing two-point functions
Baxter, et al

Optical imaging surveys measure both the galaxy density and the gravitational lensing-induced shear fields cross the sky.  Recently, the DES collaboration used a joint fit to 2-pt correlations between these observables to place tight constraints on cosmology (DES+2017).  In this work, develop the methodology to extend the DES collaboration+2017 analysis to include cross-correlations of the optical survey observables with gravitational lensing of the CMB as measured by the SPT and Planck.  Using simulated analyses, show how the resulting set of five 2pt functions increases the robustness of the cosmo constraints to systematic errors in galaxy lensing shear calibration.  Additionally, show that contamination of the SPT+Planck CMB lensing map by the thermal SZ effect is a potentially large source of systematic error for 2-pt function analyses, but show that it can be reduced to acceptable levels in the analysis by masking clusters of galaxies and imposing angular scale cuts on the 2-pt functions.  The methodology developed here will be applied to the analysis of data from the DES, the SPT, and Planck in a companion work.


1802.05273
Reinterpreting low frequency LIGO/Virgo events as magnified stellar-mass black holes at cosmological distances
Broadhurst, Diego, Smoot

GWs can be focussed by the gravity of an intervening galaxy, just like light, thereby magnifying binary merging events in the far Universe.  High magnification by galaxies is found to be responsible for the brightest sources detected in sky surveys, but the low angular resolution of LIGO/Virgo is insufficient to check this lensing possibility directly.  Here, find that the first 6 binary black hole (BBH) merging events reported by LIGO/Virgo show clear evidence for lensing in the plane of observed mass and source distance.  The four lowest frequency events follow an apparent locus in this plane, which can be reproduced by galaxy lensing, where the higher the magnification, the generally more distant the source, so the wave train is stretched more by the Universal expansion, by factors of 2-4.  This revises the reported BBH distances upwards by an order of magnitude, equal to the square root of the magnification.  Furthermore, the reported BH masses must be deceased by 2-4 to counter the larger stretch factor, since the orbital frequency is used to derive the BH masses.  This lowers the masses to 5-15 solar, well below the puzzlingly high values of 20-35 solar masses otherwise estimated, with the attraction of finding agreement in mass with BHs orbiting stars in our own Galaxy, thereby implying a stellar origin for the low frequency events in the far Universe.  Also show that the other 2 BBH events of higher frequency detected by LIGO/VIRGO, lie well below the lensing locus, consistent with being nearby and unlensed.  If this apparent division between local and distant lensed events is reinforced by new detections then the spins and masses of stellar BHs can be compared over a timespan of 10B years by LIGO/Virgo.


1802.05706
Weak lensing of intensity mapping: the cosmic infrared background
Schaan, Ferraro, Spergel

GL deflects the paths of cosmic infrared background (CIB) photons, leaving a measurable imprint on CIB maps.  The resulting statistical anisotropy can be used to reconstruct the matter distribution out to the redshifts of CIB sources.  To this end, generalize the CMB lensing quadratic estimator to any weakly non-Gaussian source field, by deriving the optimal lensing weights.  Point out the additional noise and bias caused by the non-Gaussianity and the 'self-lensing' of the source field.  Propose methods to reduce, subtract or model these non-Gaussianiities.  Show that CIB lensing should be detectable with Planck data, and detectable at high significance for future CMB experiments like CCAT-Prime.  The CIB thus constitutes a new source image for lensing studies, providing constraints on the amplitude of structure at intermediate z's between galaxies and the CMB.  CIB lensing measurements will also give valuable information on the SFH in the universe, constraining CIB halo models beyond the CIB power spectrum.  By laying out a detailed treatment of lens reconstruction from a weakly non-Gaussian source field, this work constitutes a stepping stone towards lens reconstruction from continuum or line intensity mapping data, such as the Lyman-alpha emission, absorption, and the 21cm radiation.

Day 1369

Monday.

1802.03272
The ESO Survey of non-publishing programmes
Patat, et al

One of the classic ways to measure the success of a scientific facility is the publication return, which is defined as the refereed papers produced per unit of allocated resources (for example, telescope time or proposals).  The recent studies by Sterzik+(2015,16) have shown that 30-50% of the programmes allocated time at ESO do not produce a refereed publication.  While this may be inherent to the scientific process, this finding prompted further investigation.  For this purpose, ESO conducted a Survey of Non-Publishing Programmes (SNPP) within the activities of the Time Allocation Working Group, a similar to the monitoring campaign that was recently implemented at ALMA (Stoehr+2016).  The SNPP targeted 1278 programmes scheduled between ESO periods 78 and 90 (Oct 2006 to March 2013) that had not published a refereed paper as of April 2016.  The poll was launched on 6 May 2016, remained open for 4 weeks, and returned 965 valid responses.  This article summaries and discusses the results of this survey, the first of its kind at ESO.

Day 1368

Friday.

1802.02583
The dragonfly nearby galaxies survey.  Iv. A giant stellar disk in ngc 2841
Zhang, et al

Neutral gas is commonly believed to dominate over stars in the outskirts of galaxies, and investigations of the disk-halo interface are generally considered to be in the domain of radio astronomy.  This may simply be a consequence of theft that deep HI observations typically probe to a lower mass surface density than visible wavelength data.  This paper presents low surface brightness optimized visible wavelength observations of the extreme outskirts of the nearby spiral galaxy NGC 2841.  Report the discovery of an enormous low-surface brightness stellar disk in this object.  When azimuthally averaged, the stellar disk can be traced out to a radius of ~70 kpc (5 R_25 or 23 inner disk scale lengths).  The structure n the stellar disk traces the morphology of HI emission and extended UV emission.  Contrary to expectations, the stellar mass surface density does not fall below that of the gas mass surface density at any radius.  In fact, at all radii greater than ~20 kpc, the ratio of the stellar to gas mass surface density is a constant 3:1.  Beyond ~30 kpc. the low surface brightness stellar disk begins to warp, which may be an indication of a physical connection between the outskirts of the galaxy and infall from the circumgalactic medium.  A combination of stellar migration, accretion and in-situ star formation might be responsible for building up the outer stellar disk, but whatever mechanisms formed the outer disk must also explain the constant ratio between stellar and gas mass in the outskirts of this galaxy.


1802.02581
Self-consistent redshift estimation using correlation functions without a spectroscopic reference sample
Hoyle, Rau

Present a new method to estimate z distributions and galaxy-DM bias model parameters (gdmbm) using correlation functions in a fully data driven manner.  Unlike other machine learning, template methods, or correlation z methods, this approach does not require a reference sample with known redshifts.  By measuring the projected cross- and autocorrelations of different galaxy sub-samples, e.g., chosen by cells in color-magnitude space, estimate the gdmbm parameters, and the shape of the z distributions of each sub-sample.  This method fully marginalizes over a flexible parameterization of the z distribution and gdmbm parameters of sub-samples of galaxies, and thus provides a general Bayesian framework to incorporate z uncertainty into the cosmological analysis.  The constraints are improved by an order of magnitude by including cross-correlations with the CMB and with gglensing.  Showcase how this method works using galaxies drawn from the MICE simulations, and from SDSS.  Using idealized simulations in which all gdmbm parameters and z distributions are known, this method recovers important quantities, such as the offset between the mean of the true and estimated z distribution at (7±7)e-4, and the 68% and 99.5% widths of the distributions at (1.1±1.8)%, (6.1±3.5)%.  This method can be used for distributions of galaxies for which representative spectra are either unavailable, or if there is no redshift overlap with a reference sample.  This method can naturally incorporate any information for any of the galaxy sub samples, such as either redshifts, and/or gdmbm parameter values, by either initializing the starting position of the chains during the exploration of the high dimensional parameter space, or as priors.

Day 1367

Thursday.

1802.02448
Analytical noise bias correction for weak lensing shear analysis with ERA
Okura, Futamase

Highly precise weak lensing shear measurement is required for statistical weak gravitational lensing analysis such as cosmic shear measurement to achieve severe constraint on the cosmological parameters.  For this purpose, the accurate shape measurement of background galaxies is absolutely important in which any systematic error in the measurement should be carefully corrected.  One of the main systematic error comes from photon noise which is Poisson noise of flux from the atmosphere (noise bias).  Investigate how the photon noise makes a systematic error in shear measurement with the framework of ERA method developed in earlier papers and give a practical correction method.  The method is tested by simulations with real galaxy images with various conditions and it is confirmed that it can correct 80~90% of the noise bias except for galaxies with very low signal to noise ratio.

Day 1366

Wednesday.

1802.00937
ProFound: Source Extraction and application to modern survey data
Robotham, et al

Introduce ProFound, a source finding and image analysis package.  ProFound provides methods to detect sources in noisy images, generate segmentation maps identifying the pixels belonging to each source, and measure statistics like flux, size and ellipticity.  These inputs are key requirements of ProFit, the recently released galaxy profiling package, where the design aim is that these two software packages will be used in unison to semi-automatically profile large sample of galaxies.  The key novel feature introduced in ProFound is that all photometry is executed on dilated segmentation maps that fully contain the identifiable flux, rather than using more traditional circular or ellipse based photometry.  Also, to be less sensitive to pathological segmentation issues, the de-blending is made across saddle points in flux.  Apply ProFound in a number of simulated and real world cases, and demonstrate that it behaves reasonably given its stated design goals.  In particular, it offers good initial parameter estimation for ProFIt, and also segmentation maps that follow the sometimes complex geometry of resolved sources, whilst capturing nearly all of the flux.  A number of bulge-disc decompositions projects are already making use of the ProFound and ProFit pipeline, and adoption is being encouraged by publicly releasing the software for the open source  R data analysis platform under an LGPL-3 license on GitHub (GitHub.com/asgr/ProFound).


1802.01539
ATLAS Probe: breakthrough science of galaxy evolution, cosmology, milky way, and the solar system
Wang, et al

ATLAS (Astrophysics Telescope for Large Area Spectroscopy) Probe is a concept for a NASA probe-class space mission, the spectroscopic follow-up to WFIRST, multiplexing its scientific return by obtaining deep 1 to 4 micron slit spectroscopy for ~90% of all galaxies imaged by the ~2200 sq deg WFIRST High Latitude Survey at z>0.5.  ATLAS spectroscopy will measure accurate and precise redshifts for ~300 M galaxies out to z<7, and deliver spectra that enable a wide range of diagnostic studies of the physical properties of galaxies over most of cosmic history.  ATLAS and WFIRST together will produce a 3D map of the Universe with ~Mpc resolution in redshift space.  ATLAS will: (1) revolutionize galaxy evolution studies by tracing the relation between galaxies and DM from galaxy groups to cosmic voids and filaments, from the epoch of reionization through the peak era of galaxy assembly; (2) Open a new window into the dark Universe by weighing the DM filaments using 3D WL with spectroscopic redshifts, and obtaining definitive measurements of DE and modification of General Relativity using galaxy clustering; (3) Probe the MW's dust-enshrouded regions, reaching the far side of our Galaxy; and (4) Explore the formation history of the outer SS by characterizing Kuiper Belt Objects.  ATLAS is a 1.5m telescope with a FoV of 0.4 sq deg, and uses Digital Micro-mirror Devices (DMDs) as slit selectors.  It has a spectroscopic resolution of R=600, a wavelength range of 1-4 microns, and a spectroscopic multiplex factor ~5,000-10,000.  ATLAS is designed to fit within the NASA probe-class mission  cost envelope; it has a single instrument, a telescope aperture that allows for a lighter launch vehicle, and mature technology (DMDs can reach TRL 6 within 2 years).  ATLAS will lead to transformative science over the entire range of astrophysics.


1802.01673
The THESEUS workshop 2017
Amati, et al

The Transient High-Energy Sky and Early Universe Surveyor (THESEUS) is a mission concept developed in the last years by a large European consortium, with interest in prospective participation by research groups in USA and other non-European countries.  As detailed in Amati+2017 and Stratta+2017, THESEUS aims at exploiting high-z Gamma-Ray Bursts for getting unique clues on the early Universe and, being an unprecedentedly powerful machine for the detection, accurate location and z determination of all types of GRBs (long, short, high-z, under-luminous, ultra-long) and many other classes of transient sources and phenomena, at providing a substantial contribution to multi-messenger astrophysics and time-domain astronomy.  Under these respects, THESEUS will show a beautiful synergy with the large observing facilities of the future, like E-ELT, TMT, SKA, CTA, ATHENA, in the EM domain, as well as with next-generation gravitational-waves and neutrino detectors, thus enhancing importantly their scientific return.  Moreover, it will also operate as a flexible IR and X-ray observatory, thus providing an even larger involvement of the scientific community, as is currently the case for the Swift mission.  In order to further explore the magnificent prospective science of the mission, the THESEUS consortium organized a Workshop in Napels on Oct 5-6 2017.  The program included about 50 reviews and talks from worldwide recognized exports of the fields.  The topics ranged from the description of the mission concept, instrumentation and technologies to the main, additional and observatory science, further showing the strong impact that THESEUS observations would have on several fields of astrophysics, cosmology and fundamental physics.

Day 1365

Tuesday.

1802.00817
Gravitational lensing of a star by a rotating black hole
Dokuchaev, Nazarova

The gravitational lensing of a finite star moving around a rotating Kerr black hole has been numerically calculated. Calculations for the direct image of the star and for the first and second light echos have been performed for the star moving with an orbital period of 3.22 h around the supermassive BH SgrA* at the Galactic Center.  Time dependencies for the observed star position on the celestial sphere, radiation flux from the star, frequency of detected radiation, major and minor semi axes of the lensed star image have been calculated and plotted.  The detailed observation of such lensing requires a space interferometer such as the Russian Millimetron project.  
[video: https://youtu.be/P6DneV0vk7U]


1802.01188
Where is Population II?
Mould, Bianchini, Forbes, Reichart

The concept of a pristine generation of stars, followed by a protogalactic era, and finally the mainstream stellar population is a plausible starting point for testing the physical understanding of early star formation.  This will be observationally driven as never before in the coming decade.  In this paper, search out observational tests of an idealized coeval and homogeneous distribution of population II stars.  Examine the spatial distribution of quasars, globular clusters, and they integrated free electron density of the IGM, in order to test the assumption of homogeneity.  Any real inhomogeneity implies a population II that is not coeval.


1802.01212
Non-Gaussian information from weak lensing data via deep learning
Gupta, Matilla, Hsu, Haiman

WL maps contain information beyond 2pt statistics on small scales.  Much recent work has tried to extract this information through a range of different observables or via nonlinear transformations of the lensing field.  Train and apply a 2D convolutional neural network to simulated noiseless lensing maps coving 96 different cosmological models over a range of Omega_m, sigma_8.  Using the area of the confidence contour in the Omega_m, sigma_8 plane as a figure-of-merit, derived from simulated convergence maps smoothed on a scale of 1.0 arcmin, show that the neural network yields ~5x tighter constraints than the power spectrum, and ~4 x tighter than the lensing peaks.  Such gains illustrate the extent to which WL data encode cosmological information not accessible to the power spectrum or even non-Gaussian statistics such as lensing peaks.


1802.01440
A robotic "Social Media" controlled observatory for education and research
Lane

The world's first robotic observatory to interact with its observers entirely using the social media platforms Facebook or Twitter.  The telescope "tweets" what it's doing, points live images, and responds to observer commands through a comprehensive command set.  Observation requests are queued and observed by a responsive queue engine.  Its architecture, social media based image processing capability and several usage examples are also described.

Day 1364

Monday.

1802.00734
Unveling Galaxy Bias via the Halo Model, KiDS and GAMA
Dvornik, et al

Measure the projected galaxy clustering and GGL signals using GAMA and KiDS to study galaxy bias.  Use the concept of non-linear and stochastic galaxy biasing in the framework of halo occupation statistics to constraint the parameters of the halo occupation statistics and to unveil the origin of galaxy biasing.  The bias function Gamma_{gm}(r_p), where r_p is the projected comoving separation, is evaluated using the analytical halo model from which the scale dependence of Gamma_gm(r_p), and the origin of the non-linearity and stochasticity in halo occupation models can be inferred.  The observations unveil the physical reason for the non-linearity and stochasticity, further confirmed using hydrodynamical simulations, with the stochasticity mostly originating from the non-Poissonian behavior of satellite galaxies in the DM haloes and their spatial distribution, which does not follow the spatial distribution of DM in the halo.  The observed non-linearity is mostly due to the presence of the central galaxies, as was noted from previous theoretical work on the same topic.  Also see that overall, more massive galaxies reveal a stronger scale dependence, and out to a larger radius.  The results show that a wealth of information about galaxy bias is hidden in halo occupation models.  These models should therefore be used to determine the influence of galaxy bias in cosmological studies.

Day 1363

Thursday.  Friday.

1802.00343
Gravitational starlight defection measurements during the 21 August 2017 total solar eclipse
Burns

Precise starlight positions near the sun were measured during the 21 August 2017 total solar eclipse in order to measure their gravitational deflections.  The equipment, procedures, and analysis are described in detail.  A portable refractor, a CCD camera, and a computerized mount were set up in Wyoming.  Detailed calibrations were necessary to improve accuracy and precision.  Nighttime measurements taken just before the eclipse provided cubic optical distortion corrections.  Calibrations based on star field images 7.4 deg on both sides of the sun taken during totality gave linear and quadratic plate constants.  A total of 45 images of the sky surrounding the Sun were acquired during the middle part of totality, with an integrated exposure of 22 seconds.  The deflection analysis depended on accurate star positions from the USNO's UCAC5 star catalog.  The final result was a deflection coefficient L=1.752 arcsec, compared to the theoretical value of L=1.751 arcsec, with an uncertainty of only 3%.