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Science Results from Pan-STARRS1
Talk Abstracts

Listing of Talk Abstracts

Citizen Science and PanSTARRs
Dr.  Carol Christian (STScI)
The term Citizen Science is used in myriad ways to describe the interaction of non-discipline volunteers in research endeavors. The brand of Citizen Science that is most relevant to survey type data has been initiated and successfully demonstrated by the Zooniverse project. The projects involve tasks that volunteers accomplish are aimed at scientific research that requires a large number of individuals to accomplish specific actions. These actions take advantage of human cognition and visual or auditory skills not replicated by computers. In the aggregate, the resulting analysis by volunteers is actually more robust than that accomplished through algorithms and automation. A by-product of this CitSci may be education of the volunteers and stimulation of individual interest in astronomy and science, but that is not the main goal. The product of such CitSci is research papers. I will give examples of Citizen Science projects and discuss the types of programs that might benefit PanSTARRs researchers.
Large-Scale Structure
Prof.  Shaun Cole (Durham University)
A brief review of KP12's large scale structure goals, plans and challenges.
Wide Binary Science Using Pan-STARRS1
Dr.  Niall Deacon (MPIA)
Wide binaries provide unique laboratories for studying low-mass star formation and substellar atmospheres. Pan-STARRS1 provides the ideal tool for discovering large populations of these objects with its red-sensitive detectors, multiple epochs and wide field of view. We present results of the most successful search for wide, ultracool (>M6.5) companions to date. Wide binaries may also play a role in planet formation. Hence we have been using Pan-STARRS1 and other survey data to produce a proper motion survey of the Kepler field. This will allow us to select wide binaries and to probe any possible link between planet occurrence and wide multiplicity. It also provides a valuable legacy product for characterising Kepler Objects of Interest.
Observational Constraints on the Catastrophic Disruption Rate of Main Belt Asteroids
Mr.  Larry Denneau (Institute for Astronomy)
We have calculated 90% confidence limits on the steady-state rate of impact-generated catastrophic disruptions (CD) of main belt asteroids in terms of the absolute magnitude at which one catastrophic disruption occurs per year (H0_CL) as a function of the post-disruption increase in brightness (∆m) and subsequent brightness decay rate (τ ). The confidence limits were calculated using the brightest unknown main belt asteroid with V = 18.5 detected with the Pan-STARRS 1 (PS1) telescope. We measured the PS1’s catastrophic disruption detection efficiency using the Pan-STARRS moving object processing system (MOPS) and a simple model for the CD event’s photometric behavior. Our simplistic disruption model suggests that ∆m ∼ 20 mag and 0.01mag d−1 < τ < 0.1mag d−1, implying that H0 = 28 — inconsistent with H0 = 23.26 ± 0.02 predicted by Bottke et al. (2005). We suggest that the discrepancy is due to a source of disruptions for small (< 100m) asteroids other than impact. We estimate that current and upcoming asteroid surveys may discover up to about 10 disruptions/year brighter than V = 18.5.
Towards a Complete Sample of z~6 Quasars: New Insights from Pan-STARRS1
Emanuele Paolo Farina (MPIA)
Luminous quasars at high redshift provide direct probes of the evolution of supermassive black holes (SMBH) and the intergalactic medium (IGM) at early cosmic time. Over the last decade, numerous studies have established a sample of ~70 luminous quasars at z>5.5, selected using data from the Sloan Digital Sky Survey (SDSS) and the CFHT Quasar Survey. These studies have established the existence of SMBHs less than a Gyr after the Big Bang, and the presence of almost complete Gunn-Peterson absorption, indicating the end of the reionization at z~6. These findings strongly suggest that fundamental changes are happening in the IGM at z~6-7. The discovery and characterization of a statistically significant sample of bright quasars in this redshift range is crucial to further study this important era in the history of the Universe. The unprecedented sky coverage and the deepness of the Pan-STARRS1 (PS1) survey represents a fundamental step forward in building a complete sample of high-z quasar, and the additional y-band enables the search for luminous quasars also beyond the SDSS limit (z>6.5). We discovered the first PS1 high-z quasar early in 2012 (Morganson et al. 2012), and in the last year we have published 8 additional z~6 quasars (Bañados et al. 2014). Our new sample already include quasars that are nearly a magnitude fainter that the SDSS quasars and shows a variety of quasars properties, in terms of both luminosities and spectral features. The fraction of weak-line emission quasars found in this work is much higher than in previous studies, implying that the z~6 quasar population might be more diverse than previously thought.
Magnitudes, Phase Functions and Spin Statistics of Asteroids from PS1
Alan Fitzsimmons (Queen's University Belfast)
During the PS1 surveys the IPP+MOPS pipeline has resulted in the identification of more than 7 million moving objects. The vast majority of these were main-belt asteroids. The excellent photometry available has allowed us to calculate absolute magnitudes and phase functions for a subset of ~240,000 asteroids (Veres et al, in preparation), using both the original IAU (H,G) system of Bowell et al. (1989) and the new (H,G12) system of Muinonen et al. (2010). As found by previous authors, the true absolute magnitudes are systematically fainter than current catalogues at H>16. We will present our current understanding of the biases inherent in previous studies relative to the absolute photometry from PS1. The sparse sampling present in the current PS1 catalogue prevents lightcurve solutions for most main-belt asteroids. Therefore we have measured the observed cumulative-frequency distribution of the magnitude differences present within tracklet pairs of observations. We find strong evidence of YORP-induced spin pole alignments at larger diameters. This grows weaker going down towards 1 km radius, which may imply a growing tendency for non-principal axis rotations due to collisions (McNeill et al., in preparation).
PS1 Medium Deep Survey: Luminous and Dark Matter Properties of Galaxies Up to z~1
Dr.  Sebastien Foucaud (Shanghai Jiao Tong University)
Taking advantage of the combination of area and depth of the PS1 Medium Deep Survey, I aim to explore the properties of galaxies and their dark matter haloes up to z~1. I will first discuss the quality of our data, in particular our photometric redshifts. Then I will describe the results of our studies of the evolution of the Luminosity functions and clustering analysis up to z~1. I will then introduce some preliminary results on our Halo Occupation Study, and conclude briefly on the evolution of the luminous-to-dark ratio inferred by our data up to z~1.
Mapping Dust in 3D with Pan-STARRS 1
Gregory Green (Harvard/CfA)
I present a 3D dust map of the Milky Way, based on Pan-STARRS 1 photometry of over half a billion stars. Our 3D dust map covers the footprint of the 3pi survey, tracing dust out to a distance of several kiloparsecs and a depth of a few magnitudes of reddening in E(B-V). In each pixel in the map, we infer the distance and reddening of each star, and then determine the range of reddening versus distance profiles that are consistent with all the stars along the line of sight. The map has a typical angular resolution of 7', varying with the surface density of stars across the sky, and a distance resolution of about 25%. At large distances, our map agrees well with 2D maps of dust, such as Schlegel, Finkbeiner & Davis (1998) and the newer Planck dust maps. At intermediate distances, it reveals structure from fine filamentary scales up to gross features in the Galaxy. Our current effort focuses on incorporating near-infrared photometry from 2MASS into the map, allowing us to peer through deeper clouds, where PS1 optical photometry is heavily extinguished. In the future, we will be able to leverage new datasets, such as LSST and GAIA, to produce the next generation of 3D maps of our Galaxy.
Dr.  Sebastien Heinis (University of Maryland)
I will present ongoing efforts at UMD on Medium Deep Fields. We generated band merged u,g,r,i,z,y catalogs for all Medium Deep Fields using reference stacks. The resulting catalogs contain Kron magnitudes measured on PSF-matched images, as well as PSF magnitudes measured on original images. Star/galaxy separation is achieved though optimized Support Vector Machines ran on combination of morphology, magnitude and colors. We also derive photometric redshifts which are trained on extensive spectroscopic coverage in MD04. The quality of the photometric redshifts is stable up to z~1. I will also discuss scientific applications using these catalogs. In particular, I will show preliminary results of the search for high redshifts quasars in the Medium Deep Fields, using a combination of colors and custom stacks obtained thanks to the high speed connection available at MAX/UMD to check the variability of the candidates.
Variability Selection in PS1 3pi
Nina Hernitschek (MPIA)
We explore, through the comparison of PS1 3pi data with SDSS Stripe 82 data, how well various classes of objects, in particular QSOs and RR Lyrae can be identified on the basis of the statistical properties of their multi-color light curves. Specifically, I will describe an approach that uses, and does well with, multi-band structure functions to variability-select QSOs (an pre-select RR Lyrae candidates) in PS1 3pi.
PS1 Medium Deep Survey Review and Status
Dr.  mark huber (Institute for Astronomy, Univ. of Hawaii)
The Dark Energy Survey
Dr.  David James (CTIO/NOAO)
The five-year Dark Energy Survey has just completed its first year of operation, using the Dark Energy Camera on the CTIO Blanco 4m telescope. We will map approximately 5000 sq-degrees of sky over 525-nights of observations during the 5-years of the Survey, using grizY filters to a depth of ~24th magnitudes. In order to provide a complementary probe of dark energy, the Survey area is selected to overlap with other sky surveys that can provide additional data about the galaxies viewed. These surveys include the South Pole Telescope (SPT), Sloan Digital Sky Survey (SDSS) and the Vista Hemisphere Survey (VHS). Here, we describe the physical characteristics of the 570-megapixel Dark Energy Camera, the fundamental strategy of operating and executing the Dark Energy Survey, some early science results, and plans for executing the remainder of the Survey.
PAndromeda Cepheids in M31
Mr.  Mihael Kodric (USM & MPE)
From the first year of PAndromeda observations we derive a sample of Andromeda galaxy (M31) Cepheids in the rP1 and iP1 filters. The 2009 Cepheids we find constitute the largest published Cepheid sample in M31. By determining the age of the Cepheids we are able to show that the 10 kpc ring in M31 has an age gradient. The M31 Period-Luminosity relation(PLR) we derive from this sample indicates that the PLR has a broken slope. We obtain near-infrared photometry for 413 of those 2009 Cepheids from HST observations (PHAT Dalcanton et al.(2012)). The PLRs for this sample clearly show a broken slope at a period of 10 days. With the full three years of data the Cepheid sample will significantly increase especially towards longer periods. This final sample will allow us to perform phase corrections in the near-infrared. The result will be the largest and most tightly constrained Cepheid sample for M31 in the near-infrared.
Selection of AGN and Supernovae Using Multi-BandDifference-Imaging in the Pan-STARRS1 Medium-Deep Survey
Mr.  SIDHARTH KUMAR (University of Maryland College Park)
Automated identification of AGN and SN in photometric survey catalogs is of paramount utility in an age of massive observational and computational viability, and concommitant increases in the volumes of data. We present a novel method for the classification of Pan-STARRS1 Medium Deep Survey transients with galaxy hosts into stochastic variables and transient bursts, using multi-band difference-imaging time-series data. Using a star galaxy catalog [1] to identify the extragalactic transients, we adopt a Bayesian formalism to model the difference-flux time-series of sources in four pan-STARRS1 photometric bands gP1, rP1, iP1, and zP1 using three deterministic generic supernova-like lightcurve models (Gaussian, Gamma distribution, and an analytical supernova model) and one stochastic AGN-like lightcurve model, the Ornstein-Uhlenbeck process [2]. We assess the fitnesses of the models band-wise, using their estimated leave-out-one cross-validation likelihoods and corrected Akaike information criteria (AICc), which we then combine using a K-means clustering algorithm to determine the source classification in each band. The final source classification is then derived as a combination of the individual filter classifications, resulting in two measures of classification quality; the averages across the photometric filters of 1. the classifications determined from the closest K-means cluster centers, and 2. the square distances from the clustering centers in the K-means clustering spaces. We show that AGN and SN occupy distinct regions in the plane constituted by these measures, which we identify using a support vector machines machine learning algorithm with a radial basis kernel transformation applied. We use this model to characterize 6939 extragalactic transients into 1417 bursting (SN), and 4888 stochastic (AGN) with a 5.72% contamination rate. Our method can be extended to the identification of any number of particular sub-types of known variable and transient sources, as well as facilitate the discovery of new classes of sources in existing survey catalogs. References [1] Sebastien Heinis et al. ApJ, In prep. [2] G. E. Uhlenbeck and L. S. Ornstein. On the theory of the brownian motion. Phys. Rev., 36:823–841, Sep 1930
Optical Study of Blazars
Dr.  Omar  Kurtanidze (Abastumani Observatory)
To study optical variability of extragalactic objects, namely blazars, we are conducting in Abastumani Observatory since 1997 a long-term campaign using dedicated telescopes, which allowed to collect ~300 000 CCD frames during 2 800 nights. This extensive monitoring campaign over 100 blazars during 1st five years was carried out in BVRI bands and later on mainly in R band using the 70-cm meniscus (f/3, SBIG ST6 and Apogee Ap6E) and 125-cm Ritchey-Chretien (f/13, Apogee Ap6E) telescopes. The list of sources includes blazars detected from Radio to TeV band. Most densely sampled sources are BL Lacertae, S5 0716+710, 3C 66A, 1ES 1959+650, Mrk 421 and others. The results on variability study of these sources on different time-scales are presented. Besides, to extend in the future optical photometric, polarimetric and spectral survey of fainter sources with high temporal resolution, we are considering purchase of two PanSTAR like telescopes.
Milky Way Satellites
Mr.  Benjamin Laevens (MPIA/Strasbourg Observatory)
I will present the results of the search for new Milky Way dwarf galaxies using the Pan-STARRS data. With new coverage of the sky equalling that of the SDSS again and attaining depths similar to the aforementioned survey, Pan-STARRS gives us an unprecedented and unique opportunity to search for new Milky Way satellites and study their 3-dimenional distribution. However, no obvious new candidates was discovered in the new coverage not probed by the SDSS, suggesting a dearth dearth of new Milky Way satellites.This result is interesting in the context of Lambda-CDM, where this anisotropic distribution of Dwarf Galaxies at odds with expectations. This result is interesting for two main reasons: it reinforces the idea of a plane of satellites around the Milky Way with none outwith the plane, whilst at the same time not extending this plane to Southern regions. In this talk, I will present my search strategy and discuss the implications of these results on the cosmological paradigm.
Slow-Blue Extragalactic Transients: Progress Report
Prof.  Andy Lawrence (Institute for Astronomy, University of Edinburgh)
At the PS1 meeting in Durham, we reported the discovery of new class of extragalactic transient, that we believe represent high z=1 AGN undergoing high amplitude microlensing events by z=0.2 foreground galaxies. We now have much more extensive light curves, multi-epoch spectra, and some X-ray data, which strengthen the case for microlensing. I will summarise results so far, and the prospects for continued studies and their importance in studying the structure of AGN, as well as other things such as the binary fraction in external stellar populations.
Variable Stars and Eclipsing Binaries in M31
Dr.  Chien-Hsiu Lee (MPE)
The high cadence, long-term PS1 Andromeda monitoring campaign (PAndromeda) yields well-sampled light curves that drastically improve our understanding of variables in M31. First of all, using the SigSpec package (Reegen 2007), we identify 17 double-mode Cepheids pulsating in the fundamental mode and first overtone. Their period ratios enable us to derive their metallicities, and infer the metallicity gradient of M31. Secondly, with photometric and variability diagnostics, we are able to find 4 luminous blue variable (LBV) candidates that share the same properties of known M31 LBVs. Once these candidates are confirmed spectroscopically, our selection method can be applied to identify local group LBVs, hence shed lights on their properties, such as duration, mass loss, etc.. Last but not the least, applying the modified box-fitting routine by Zendejas Dominguez et al. (2013), we detect ~300 eclipsing binaries towards M31. A dozen of them are brighter than 20 mag in V, and have the potential to render M31 a distance anchor.
The Effect of Environment On the Properties of the Main-Sequence and Quiescent Fraction in the PS1 Medium Deep Survey
Dr.  Lihwai  Lin (ASIAA)
Using groups and clusters identified with probability friend-of-friend (PFOF) group finder from the PS1 Medium Deep Survey, we study the impacts of the environment on the star formation activities of galaxies. While the fraction of quiescent galaxies increases from the field, to the group- and cluster-like environment, the slope and amplitude of the star-forming sequence is insensitive to the environment, favoring a fast quenching process operating in the overdense environments. By studying the stellar mass dependence of the mass- and environment- quenching efficiency, we conclude that the mass quenching is a dominant process in quenching the star formation for massive galaxies, while the environment quenching is more important for less massive galaxies.
Searching For and Characterization Star Clusters Toward the Galactic Anti-Center from Pan-STARRS1 3pi Survey
Mr.  Chien-Cheng Lin (National Central University)
Most if not all stars formed clustered in molecular clouds. Star clusters are relative easier to determine ages, distances, and chemical abundances than a single star, therefore, they serve as laboratories to test stellar evolutionary models and as probes to study the Galactic structure via dynamical interactions with Galactic environments. While some hundreds of thousand open clusters are expected on the Galactic disk, so far only a few thousands have been catalogued, all in the solar neighborhood, with a fraction of which are characterized with cluster parameters and member lists. The incompleteness of the open cluster sample is largely due to the extinction in the disk and also due to the lack of systematic search in sky surveys covering sufficient volume in space. We aim to use PS1 3pi data to search for and characterize star clusters, because with its wide field of views and sensitive cameras we can improve the sample and members as complete as possible. The pilot program is to identify stellar density enhancements toward the Galactic anti-center, we obtained a total of 491 stellar cluster candidates in a field of 20° × 20°, of which 53 are known star clusters. The remaining 437 candidates are also verified their size, shape, number of members, reddening, distances, and ages with proper motions and multiple bands photometries. We will also present how our study improves significantly the star cluster sample toward the Galactic Anti-Center.
Active Centaurs in PS1
Dr.  Edward Lin (National Central University)
The Centaurs are solar system bodies with orbits among four giant planets. This class of object is the transitional population between the Kuiper belt objects and the Jupiter-family comets. Some of them show the cometary activities so called “active Centaurs”. In this talk, we present the recent result of PS1 observations of an active Centaur "P/2011 S1 (Gibbs)" and the monitoring result of other known active Centaurs. Analysis of PS1 images reveals that P/2011 S1 (Gibbs) has a small nucleus < 4 km radius, with colors gP1 − rP1 = 0.5 ± 0.02, rP1 − iP1 = 0.12 ± 0.02 and iP1 − zP1 = 0.46 ± 0.03. The comet remained active from 2010 to 2012, with a model-dependent mass-loss rate of ~ 100 kg/s. The mass-loss rate per unit surface area of P/2011 S1 (Gibbs) is as high as that of 29P/Schwassmann-Wachmann 1 (29P/SW1), making it one of the most active Centaurs. The mass-loss rate also varies with time from ~ 40 kg/s to 150 kg/s. The monitoring result indicated several outburst events of 29P/SW1. We also find that most of the active Centaurs have relatively small heliocentric distant.
Generating the Template Light Curves of Galactic Cepheids in PanSTARRS 1 SystemPhotometry: Preliminary Results
Miss  ILING LIN (Institute of Astronomy, National Central University,Taiwan)
Cepheids are standard candles that can be used to determine distances to nearby galaxies by using well-calibrated period-luminosity (P-L) relations . Properties of Cepheids are well examined in BVI filters; however they are not well studied in grizy filters. Therefore, we carried out a project to investigate and characterize the known Galactic Cepheids, by reconstructing their light curves and deriving their mean magnitudes in Pan-STARRS1 (PS1, the Panoramic Survey Telescope and Rapid Response System) grizy photometry system. PS1 is a multi-band and multi-epoch survey project by using a dedicated 1.8 meter wide field telescope (located at Mount Haleakela, Mauna Kea, Hawaii). PS1 telescope is equipped with a CCD camera that has with 1.4 billion pixels, composed with 60 Orthogonal Transfer Arrays (OTAs), to form a field of view of 7 degree square. The OTA consists of 8 x 8 array of 600 x 600 pixels CCDs. The camera include a set of 5 filters: g, r, i, z, and y . PS1 science goals range from Solar System to cosmology. Considering the depth and coverage area requirements are different for various science goals, five distinct survey programs are performed: the 3π sky survey (covering the northern sky to -30° in declination), the median-deep survey of selected areas (MD survey), the Solar System sweep spot survey, the stellar transit survey, and a deep survey of M31 (PAndromeda survey). Observed data are reduced and analyzed by IPP (Image Processing Pipeline) team. Because the data points of our targeted Cepheids in 3π sky survey are sparse and highly clumped. Therefore, we need to construct template light curves by selecting the 1440 fundamental mode (FM) Cepheids in M31 observed only in the r- and i- band from PS1 PAndromeda survey. We first queried the periods, the epochs of maximum brightness, and the mean magnitudes of all sampled Cepheids in r- and i- band. Then we fitted a Fourier expansion to the normalized and folded light curves based on the observed data points for all targets. Finally, we stacked similar light curves to construct template light curves in the r- and i- band. Using these template light curves, we present the reconstructed r- and i-band light curves of Galactic FM Cepheids in 3π sky survey, as well as their mean magnitudes based on the template light curves fitting.
Photometric Redshift Estimation of Planck Cluster Candidates from Pan-STARRS
Mr.  Jiayi Liu (Ludwig-Maximilians Universitat)
We present the Panoramic Survey Telescope & Rapid Response System (Pan-STARRS) optical follow up of the Planck Sunyaev- Zel’dovich (SZ) sources of unconfirmed galaxy clusters that overlap with PS1. We use 151 Planck confirmed galaxy clusters with spectroscopic redshifts to examine our redshift estimation pipeline and reach an accuracy of σ_{z/(1+z)} ∼ 0.025. Of the 249 unconfirmed cluster candidates we are able to measure photometric redshifts for 1/3 of the cluster sample and we find that a quarter of the candidates are heavily contaminated by stars near the Galactic plane. For the remaining candidates we report a lower redshift limit based on the expected halo occupation number of a 10^15 M_solar cluster given the depth of the optical data at that location.
Finding Variability Signatures of Supermassive Black Hole Binaries with the Pan-STARRS1 Medium Deep Survey
Ms.  Tingting Liu (University of Maryland)
We applied the differential photometry technique of inhomogeneous ensemble photometry on the Pan-STARRS1 (PS1) Medium Deep (MD) survey to construct high quality light curves of variable quasars. We followed the methodology of Bhatti et al. (2010), who adapted the technique described in Honeycutt (1992) to the SDSS Stripe 82 survey. We identified ~1000 candidate variables in the MD09 field through this technique and cross-matched them with a CFHT/PS1 catalog of deep stacked images (Heinis et al. in preparation). We obtained a sample of 39 variable quasars and applied Lomb-Scargle periodogram (Horne & Baliunas 1986) to look for periodic variability, motivated by the science goal of searching for variability signatures indicative of accretion in a binary supermassive black hole system. Additionally, we used the Monte Carlo method to investigate the recovery rate of simulated periodic light curves in order to determine the black hole masses and mass ratios we are sensitive to given the sampling of the MD survey.
LSST: Current Status and Future Challenges
Robert Lupton (Princeton University)
The LSST project confidently expects to receive a Construction Start from the NSF in July 2014. I shall review the design and status of the hardware (telescope and camera) and software systems. In the context of the data processing I'll talk about some of the algorithmic issues that we face, and sketch how we plan to attack some of them. I will also discuss some of the difficulties involved in organizing and running a large distributed scientific endeavor, and indicate ways that members of the PS1SC can get involved.
Results from the Star/Galaxy Separation Working Group
Dr.  Nicolas Martin (MPIA & Strasbourg Obs.)
Early Results from the Time Domain Spectroscopic Survey
Dr.  Eric Morganson (CFA)
The Time Domain Spectroscopic Survey (TDSS) is an SDSS IV project that will obtain spectra of 250,000 of the most variable objects across 14,000 square degrees of the sky. In addition to being an order of magnitude larger than any previous spectroscopic variable survey, TDSS will also be the first major spectroscopic survey to be selected in an intentionally unbiased way without regard for color or specific light curve character. The PS1 3Pi survey is essential for our candidate selection. Our variable candidates are selected using PS1-SDSS magnitude differences as well as PS1-only variability. PS1 data and our Kernel Density Estimate selection algorithm allow us to produce a candidate list that is roughly 98% pure and covers a wide variety of astrophysical sources. TDSS began taking spectra earlier this year and has already discovered a number of exciting sources.
Slowly-Evolving Super-Luminous Supernovae
Mr.  Matt Nicholl (Queen's University Belfast)
Extremely luminous (M<-21) supernovae in dwarf galaxies are challenging our understanding of stellar evolution and explosion. Those which fade slowly, such as SN 2007bi, are thought to be associated with very-high-nickel-mass, ‘pair-instability’ supernovae. Faster events, like SN 2010gx, may be associated either with a central engine or a strong circumstellar interaction. We present data and modelling of two 2007bi-like supernovae, at z=0.107 and z=0.524, with early detections from PS1. These allow us to probe the light curve physics of these events in detail, while early spectra suggest common properties between the slowly- and quickly-evolving subclasses.
Preliminary Results of Pan-Planets
Christian Obermeier (MPIA Heidelberg)
Pan-Planets is one of the 12 key science projects of the Pan-STARRS 1 Science Consortium. Its main scientific focus is the detection of transiting Hot Jupiters around M dwarfs. We present the results of our ongoing search for exoplanets. Due to an extremely high number of M dwarfs observed by Pan-Planets, we are able to calculate more precise upper limits for the fraction of M dwarfs with Hot Jupiter companions. Furthermore, we will present our method of determining the stellar characteristics of the host stars in our FOV and the subsequent selection of M dwarfs. Pan-Planets enables us to do a large variety of secondary science goals, e.g. the detection of eclipsing binary systems, flare stars or mininovae which we will highlight in our presentation.
Cosmological Constraints from SN Ia Discovered During the First 1.5 Years of the PS1 Survey
Dr.  Armin Rest (STScI)
We present griz light curves of 146 spectroscopically confirmed Type Ia Supernovae (0.03 < z <0.65) discovered during thefirst 1.5 years of the PS1 Medium Deep Survey. A Hubble diagram is constructed with a subset of 113 SNe Ia that pass our light curve quality cuts. The cosmological fit to 310 SNe Ia (113 PS1 SNe Ia + 197 low-z SNe Ia), using only SNe and assuming a constant dark energy equation of state and flatness, yields w = −1.120, with statistical and systematic uncertainties of the order of 0.25. When combined with BAO+CMB(Planck)+H0, the analysis yields w = −1.166, with upper and lower 1-sigma limits of +0.072 and −0.069, respectively, including all identified systematics. The value of w is inconsistent with the cosmological constant value of −1 at the 2.3-sigma level.
Refining the Hubble Constant with Parallax, Cepheids and Supernovae
Dr.  Adam Riess (JHU)
The Hubble constant remains one of the most important parameters in the cosmological model, setting the size and age scales of the Universe. Present uncertainties in the cosmological model including the nature of dark energy, the properties of neutrinos and the scale of departures from flat geometry can be constrained by measurements of the Hubble constant made to higher precision than was possible with the first generations of Hubble Telescope instruments. Streamlined distances ladders constructed from infrared observations of Cepheids and type Ia supernovae with ruthless attention paid to systematics now provide 3.5% precision and offer the means to do much better. While WFC3 has helped open this new route, its full exploitation can come from a new technique, Parallel Astrometric Spatial Scanning (PASS), to measure parallax distances beyond a kiloparsec. Transient, optical surveys like Pan-STARRS can help by identifying Cepheids in the Milky Way or nearby galaxies. I will review recent and expected progress.
The Milky Way's Dust and PanSTARRS1
Dr.  Eddie Schlafly (MPIA)
The PS1 survey has enabled detailed and systematic studies of dust in the Milky Way not before possible. I present results from our ongoing project to use the PS1 photometry to map the Galaxy's dust. This effort has so far produced a new Bayesian framework for simultaneously inferring the reddenings, distances, and properties of stars from their PS1 photometry; a new, high-resolution map of dust reddening covering three-quarters of the sky; a catalog of distances to high-latitude molecular clouds; and the unveiling of a new shell of dust in the Orion Molecular Complex. We are close to releasing maps of the full 3D distribution of dust in the nearby Galaxy and combining these 3D maps with gas kinematics to study the Galaxy's rotation curve. The future of these dust-mapping efforts is promising: the recent availability of Planck data and upcoming availability of Gaia data will open additional windows onto the properties of the Milky Way's dust.
Improvements to the Pan-STARRs Supernova Analysis
Dr.  Daniel Scolnic (Johns Hopkins University)
We discuss the main systematic uncertainties in the current Pan-STARRs Type Ia Supernova Analysis and improvements to this analysis. We present an update on the full spectroscopic sample as well as the photometric sample, and methods to improve the overall calibration and various pieces of the analysis.
PAndromeda: Microlenses & Variable Stars: Results and Ongoing Work
Stella  Seitz (USM-MPE)
PAndromeda is the 3 year M31-monitoring compaign of PanSTARRS-1. In this talk we summarize the data-quality and data products from the PAndromeda Key-Project. Since the Key-Project runs its own pipeline for the photometric alignment of the PS1-preprocessed data and applies rigorous masking of artefacts, our difference imaging light curves have well controlled photometric errors, and are suitable to identify and analyze short term events (novae and microlensing events) and to systematically study the variable star content of M31. We also astrometrically aligned the public HST-PHAT data to obtain own DOLPHOT photometry at the positions of (variable and resolved) sources detected in the PAndromeda-data. We show published and new results regarding the identification of microlensing events and the identification and analysis (eg. PLR, ages) of ~2000 cepheids using PAndromeda and PHAT data. Furthermore ~300 eclipsing binaries found with the light curve analysis are characterized using PS1 and (where available) PHAT photometry and the Wilson-Deviney algorithm. We have developed a new LBV identification method by combining optical variability and optical & 2MASS color criteria, confirmed known LBVs and found 4 new candidates which are under spectroscopic follow up now. We will also present a preliminary infrared PLR for ~4000 LPV variables found in the combined r- and i-band analysis. The KP's own PS1 data products (and linked HST-PHAT photometry) can be made available for external collaborators.
Producing Science with the Palomar Transient Factory
Dr.  Branimir Sesar (Max Planck Institute for Astronomy)
The Palomar Transient Factory (PTF) is a fully-automated, wide-field survey for a systematic exploration of the optical transient and variable sky. The survey, now in its 5th year of operation, has enabled studies of Solar System bodies, the structure of the Milky Way, and the evolution of massive stars. I will give an overview of the survey and mention its recent successes. As an example of a study enabled by PTF, I will describe how one can use RR Lyrae stars discovered by PTF to constrain the number of low-luminosity dwarf satellites that are estimated to orbit the Milky Way in the hundreds.
Science with the Pan-STARRS1 Science Consortium Surveys
Prof.  Stephen Smartt (Queen's University Belfast)
The Pan-STARRS1 Science Consortium was formed to carry out surveys with the 7 square degree camera on the 1.8m PS1 telescope. The whole visible sky north of declination -30 degrees has been covered approximately 12 times in each of the filters grizy, making up the "3 Pi" survey. Ten medium deep fields (a total of 70 square degrees) were observed with nightly cadence along with an M31 dedicated campaign and a search for transiting planets. The consortium plans to make the data public through STScI archive in 2015. This talk will review the science highlights so far from Pan-STARRS1 and illustrate the scientific promise and legacy of this immense data set.
Quantitative, Physical Galaxy Morphology from the Pan-STARRS1 Optical Galaxy Survey (POGS)
Dr.  David Thilker (Johns Hopkins University)
We will present results from our PS1-based effort to obtain a comprehensive, physically-interpreted view of z ~ 0 galaxy structure via pixel-SED fitting of resolved galaxies. This project is the basis for the PS1 Optical Galaxy Survey (POGS, To accomplish the intensive data processing required, we created a successful distributed computing network, enabled by volunteer citizen scientists. Our early work has focused on imaging from PS1 and SDSS, but we are now in the process of broadening our spectral scope to the UV-IR domain. For thousands of galaxies, we are determining maps of key physical parameters. We will compute CAS+Gini+M_20 non-parametric morphology indicators based on the images of stellar mass (M*) and extinction-free star formation rate (SFR) resulting from pixel-SED fitting. Further, parametric models of galaxy structure (bulge, disk, bar) will be derived directly using the stellar mass maps. Our overarching science goal is understanding the evolution of galaxies with respect to their position and trajectory in the global (M*, SFR) plane, using maximally orthogonal, quantitative measures of stellar structure and SF modes obtained from our physical parameter maps.
Dusty Massive Evolved Stars in the Nearby Universe
Dr.  Stephen Williams (National Observatory of Athens)
Mass loss in massive evolved stars will reveal itself with an infrared excess via dust. We have made use of extensive Spitzer archival observations which have allowed us to explore this population of stars in nearby galaxies as identified by their mid-IR photometric properties. Here, we describe the survey and our initial results. With follow-up spectroscopy, we have identified several red and yellow supergiants, as well as luminous blue variable candidates. The goal of the survey is to determine the importance and frequency of mass loss in the late stages of massive star stellar evolution. Pan-STARRS will aid in the identification of candidate massive stars and in categorizing their variability, possibly giving clues as to the underlying mass loss mechanisms. The role of mass loss from massive stars, especially episodic mass loss in evolved massive stars, is one of the outstanding open questions facing stellar evolution theory, and the results of our survey will provide crucial data on the properties and statistics of systems mostly obscured by their own mass loss.
Machine Learning for Transient Recognition in Pan-STARRS1 Difference Imaging.
Mr.  Darryl Wright (Queen's University Belfast)
The problem of reliable transient detection in large data streams that contain many artefacts as a result of difference imaging is common to modern synoptic sky surveys such as Pan-STARRS1. Currently the process of selecting real transients from the artefacts is left to human scanners. We attempt to construct a machine learned classification system that is scalable to the next generation of all-sky surveys that will allow us to select only images of real transients providing a reliable stream of sources for scientific follow-up.
The Structure and Stellar Content of the Outer Disks of Galaxies: 1D Radial Profile and 2D Stack Images
Mr.  Zheng Zheng (JHU)
Seven hundred face-on non-interacting nearby disk galaxies selected from the Pan-STARRS1 (PS1) Medium Deep Survey (MDS) are analyzed using both 1D radial profile and 2D stack techniques. The surface brightness (SB) radial profiles are measured down to about 29 ABmag/arcsec^2. The radial SB profiles are then analyzed using the advanced SED fitting software MAGPHYS (da Cunha et al. 2008) to determine the radial profiles of the stellar mass surface density and the parameters that characterize the stellar population (such as stellar mass-to-light ratio, specific star formation rate and luminosity-weighted mean age). Radial profiles of stellar mass surface density generally show a single exponential function up to $sim 2.5 r_{90}$. In contrast, the stellar mass-to-light ratio radial profiles generally have a 'U'-shape, decreasing initially from the center of the galaxy to a minimum value at about $sim 0.7$ to 1,$ r_{90}$, and then increasing in the outer disk. Many SB profiles show a break around r90. Therefore we classify the SB profiles into three catagories following Pohlen&Trujillo (2006, hearafter PT06): up-bending, down-bending and single exponential. The down-bending profiles have a fraction of about 61% roughtly the same as PT06 (60%) but the up-bending profiles have a much smaller fraction (14%) comparing to PT06(30%) and the single exponential profiles have a larger fraction (24%) comparing to PT06 (10%). The stellar mass radial profiles can be well described by single exponential profile in most cases. The mass-to-light ratio profiles for down-bending galaxies generally have a 'U' shape. But the mass-to-light ratio profiles for up-bending and single exponential usually decrease from the center and reach a minimum plateu at around r90. This is consistent with Bakos et al. (2008) We also co-add all the galaxy images together to get a much deeper 2D image of a generic face-on disk galaxy. The 2D stack image can reach down to about 32 ABmag/arcsec^2. Both 1D radial profile and 2D Galfit analysis show clear stellar halo component between 2*r90 and 4*r90.