Tidal streams of globular clusters are ideal tracers of the Galactic gravitational potential. Compared to the few known, complex and diffuse dwarf-galaxy streams, they are kinematically cold, have thin morphologies and are abundant in the halo of the Milky Way. Their coldness and thinness in combination with potential epicyclic substructure in the vicinity of the stream progenitor turns them into high-precision scales. With the example of Palomar 5, we demonstrate how modeling of a globular cluster stream allows us to simultaneously measure the properties of the disrupting globular cluster, its orbital motion, and the gravitational potential of the Milky Way.

A. H. W. Küpper E. Balbinot A. Bonaca K. V. Johnston D. W. Hogg P. Kroupa B. X. Santiago

The outer Galactic halo is home to a number of substructures which still have an uncertain origin, but most likely are remnants of former interactions between the Galaxy and its former satellites. Triangulum-Andromeda (TriAnd) is one of these halo substructures, found as an overdensity of 2MASS M giants. We analyzed the region of Triangulum-Andromeda using photometric data from the Ninth Data Release of Sloan Digital Sky Survey (SDSS DR9). By comparing the observations with simulations from the TRILEGAL Galactic model, we were able to identify and map several scattered overdensities of main sequence stars that seem to be associated with TriAnd over a large area covering $\sim 500$ deg$^2$. One of these excesses may represent a new stellar overdensity. We also briefly discuss an alternative hypothesis, according to which TriAnd is one of the troughs of oscillation rings in the Galactic disk.

H. D. Perottoni H. J. Rocha-Pinto L. Girardi E. Balbinot B. X. Santiago S. R. Majewski F. Anders L. Da Costa M. A. G. Maia

In a one parameter family of dilaton gravity theories which allow the coupling of the dilaton to gravity and to a U(1) gauge field to differ, we have found the existence of everywhere regular spacetimes describing black holes hiding expanding universes inside their horizon.

R. Balbinot A. Fabbri L. Mazzacurati

Recently proposed 2D anomaly induced effective actions for the matter-gravity system are critically reviewed. Their failure to correctly reproduce Hawking's black hole radiation or the stability of Minkowski space-time led us to a modification of the relevant ``quantum'' matter stress energy tensor that allows physically meaningful results to be extracted.

R. Balbinot A. Fabbri

The quantum stress tensor in the Unruh state for a conformal scalar propagating in a 4D Schwarzschild black hole spacetime is reconstructed in its leading behaviour at infinity and near the horizon by means of an effective action derived by functionally integrating the trace anomaly.

Roberto Balbinot Alessandro Fabbri Ilya Shapiro

The Dark Energy Camera has captured a large set of images as part of Science Verification (SV) for the Dark Energy Survey. The SV footprint covers a lar ge portion of the outer Large Magellanic Cloud (LMC), providing photometry 1.5 magnitudes fainter than the main sequence turn-off of the oldest LMC stel lar population. We derive geometrical and structural parameters for various stellar populations in the LMC disk. For the distribution of all LMC stars, we find an inclination of $i=-38.14^{\circ}\pm0.08^{\circ}$ (near side in the North) and a position angle for the line of nodes of $\theta_0=129.51^{\circ}\pm0.17^{\circ}$. We find that stars younger than $\sim 4$ Gyr are more centrally concentrated than older stars. Fitting a projected exponential disk shows that the scale radius of the old populations is $R_{>4 Gyr}=1.41\pm0.01$ kpc, while the younger population has $R_{<4 Gyr}=0.72\pm0.01$ kpc. Howe ver, the spatial distribution of the younger population deviates significantly from the projected exponential disk model. The distribution of old stars suggests a large truncation radius of $R_{t}=13.5\pm0.8$ kpc. If this truncation is dominated by the tidal field of the Galaxy, we find that the LMC is $\simeq 24^{+9}_{-6}$ times less massive than the encircled Galactic mass. By measuring the Red Clump peak magnitude and comparing with the best-fit LM C disk model, we find that the LMC disk is warped and thicker in the outer regions north of the LMC centre. Our findings may either be interpreted as a warped and flared disk in the LMC outskirts, or as evidence of a spheroidal halo component

Eduardo Balbinot B. X. Santiago L. Girardi A. Pieres L. N. da Costa M. A. G. Maia R. A. Gruendl A. R. Walker B. Yanny A. Drlica-Wagner A. Benoit-Levy T. M. C. Abbott S. S. Allam J. A nnis J. P. Bernstein R. A. Bernstein E. Bertin D. Brooks E. Buckley-Geer A. Carnero Rosell C. E. Cunha D. L. DePoy S. Desai H. T. Diehl P. Doel J. Estrada A. E. Evrard A. Fausti Ne to D. A. Finley B. Flaugher J. A. Frieman D. Gruen K. Honscheid D. James K. Kuehn N. Kuropatkin O. Lahav M. March J. L. Marshall C. Miller R. Miquel R. Ogando J. Peoples A. Plazas V. Scarpine M. Schubnell I. Sevilla-Noarbe R. C. Smith M. Soares-Santos E. Suchyta M. E. C. Swanson G. Tarle D. L. Tucker R. Wechsler J. Zuntz

We report the discovery of a stellar stream in the Dark Energy Survey (DES) Year 1 (Y1A1) data. The discovery was made through simple color-magnitude filters and visual inspection of the Y1A1 data. We refer to this new object as the Phoenix stream, after its resident constellation. After subtraction of the background stellar population we detect a clear signal of a simple stellar population. By fitting the ridge line of the stream in color-magnitude space, we find that a stellar population with age $\tau=11.5\pm0.5$ Gyr and $[Fe/H]<-1.6$ located 17.5$\pm$0.9 kpc from the Sun gives an adequate description of the stream stellar population. The stream is detected over an extension of 8$^{\circ}.$1 (2.5 kpc) and has a width of $\sim$54 pc assuming a Gaussian profile, indicating that a globular cluster is a probable progenitor. There is no known globular cluster within 5 kpc compatible with being the progenitor of the stream, assuming that the stream traces its orbit. We examined overdensities along the stream, however no obvious counterpart bound stellar system is visible in the coadded images. We also find overdensities along the stream that appear to be symmetrically distributed - consistent with the epicyclic overdensity scenario for the formation of cold streams - as well as a misalignment between the Northern and Southern part of stream. Despite the close proximity we find no evidence that this stream and the halo cluster NGC 1261 have a common accretion origin linked to the recently found EriPhe overdensity (Li et al. 2016).

E. Balbinot B. Yanny T. S. Li B. Santiago J. L. Marshall D. A. Finley A. Pieres T. M. C. Abbott F. B. Abdalla S. Allam A. Benoit-Lévy G. M. Bernstein E. Bertin D. Brooks D. L. Burke A. Carnero Rosell M. Carrasco Kind J. Carretero C. E. Cunha L. N. da Costa D. L. DePoy S. Desai H. T. Diehl P. Doel J. Estrada B. Flaugher J. Frieman D. W. Gerdes D. Gruen R. A. Gruendl K. Honscheid D. J. James K. Kuehn N. Kuropatkin O. Lahav M. March P. Martini R. Miquel R. C. Nichol R. Ogando A. K. Romer E. Sanchez M. Schubnell I. Sevilla-Noarbe R. C. Smith M. Soares-Santos F. Sobreira E. Suchyta G. Tarle D. Thomas D. Tucker A. R. Walker

We report the discovery of an excess of main sequence turn-off stars in the direction of the constellations of Eridanus and Phoenix from the first year data of the Dark Energy Survey (DES). The Eridanus-Phoenix (EriPhe) overdensity is centered around l~285 deg and b~-60 deg and spans at least 30 deg in longitude and 10 deg in latitude. The Poisson significance of the detection is at least 9 sigma. The stellar population in the overdense region is similar in brightness and color to that of the nearby globular cluster NGC 1261, indicating that the heliocentric distance of EriPhe is about d~16 kpc. The extent of EriPhe in projection is therefore at least ~4 kpc by ~3 kpc. On the sky, this overdensity is located between NGC 1261 and a new stellar stream discovered by DES at a similar heliocentric distance, the so-called Phoenix Stream. Given their similar distance and proximity to each other, it is possible that these three structures may be kinematically associated. Alternatively, the EriPhe overdensity is morphologically similar to the Virgo overdensity and the Hercules-Aquila cloud, which also lie at a similar Galactocentric distance. These three overdensities lie along a polar plane separated by ~120 deg and may share a common origin. Spectroscopic follow-up observations of the stars in EriPhe are required to fully understand the nature of this overdensity.

T. S. Li E. Balbinot N. Mondrik J. L. Marshall B. Yanny K. Bechtol A. Drlica-Wagner D. Oscar B. Santiago J. D. Simon A. K. Vivas A. R. Walker M. Y. Wang T. M. C. Abbott F. B. Abdalla A. Benoit-Lévy G. M. Bernstein E. Bertin D. Brooks D. L. Burke A. Carnero Rosell M. Carrasco Kind J. Carretero L. N. da Costa D. L. DePoy S. Desai H. T. Diehl P. Doel J. Estrada D. A. Finley B. Flaugher J. Frieman D. Gruen R. A. Gruendl G. Gutierrez K. Honscheid D. J. James K. Kuehn N. Kuropatkin O. Lahav M. A. G. Maia M. March P. Martini R. Ogando A. A. Plazas A. K. Romer A. Roodman E. Sanchez V. Scarpine M. Schubnell I. Sevilla-Noarbe R. C. Smith M. Soares-Santos F. Sobreira E. Suchyta M. E. C. Swanson G. Tarle D. Tucker Y. Zhang

We obtained SOAR telescope B and V photometry of 14 star clusters and 2 associations in the Bridge tidal structure connecting the LMC and SMC. These objects are used to study the formation and evolution of star clusters and associations under tidal stresses from the Clouds. Typical star clusters in the Bridge are not richly populated and have in general relatively large diameters (~30-35 pc), being larger than Galactic counterparts of similar age. Ages and other fundamental parameters are determined with field-star decontaminated photometry. A self-consistent approach is used to derive parameters for the most-populated sample cluster NGC 796 and two young CMD templates built with the remaining Bridge clusters. We find that the clusters are not coeval in the Bridge. They range from approximately a few Myr (still related to optical HII regions and WISE and Spitzer dust emission measurements) to about 100-200 Myr. The derived distance moduli for the Bridge objects suggests that the Bridge is a structure connecting the LMC far-side in the East to the foreground of the SMC to the West. Most of the present clusters are part of the tidal dwarf candidate D 1, which is associated with an H I overdensity. We find further evidence that the studied part of the Bridge is evolving into a tidal dwarf galaxy, decoupling from the Bridge.

E. Bica B. Santiago C. Bonatto R. Garcia-Dias L. Kerber B. Dias B. Barbuy E. Balbinot

We present a forward-modelling simulation framework designed to model the data products from the Dark Energy Survey (DES). This forward-model process can be thought of as a transfer function -- a mapping from cosmological and astronomical signals to the final data products used by the scientists. Using output from the cosmological simulations (the Blind Cosmology Challenge), we generate simulated images (the Ultra Fast Image Simulator, Berge et al. 2013) and catalogs representative of the DES data. In this work we simulate the 244 sq. deg coadd images and catalogs in 5 bands for the DES Science Verification (SV) data. The simulation output is compared with the corresponding data to show that major characteristics of the images and catalogs can be captured. We also point out several directions of future improvements. Two practical examples, star/galaxy classification and proximity effects on object detection, are then used to demonstrate how one can use the simulations to address systematics issues in data analysis. With clear understanding of the simplifications in our model, we show that one can use the simulations side-by-side with data products to interpret the measurements. This forward modelling approach is generally applicable for other upcoming and future surveys. It provides a powerful tool for systematics studies which is sufficiently realistic and highly controllable.

C. Chang M. T. Busha R. H. Wechsler A. Refregier A. Amara E. Rykof M. R. Becker C. Bruderer L. Gamper B. Leistedt H. Peiris T. Abbott F. B. Abdalla E. Balbinot M. Banerji R. A. Bernstein E. Bertin D. Brooks A. Carnero Rosell S. Desai L. N. da Costa C. E Cunha T. Eifler A. E. Evrard A. Fausti Neto D. Gerdes D. Gruen D. James K. Kuehn M. A. G. Maia M. Makler R. Ogando A. Plazas E. Sanchez B. Santiago M. Schubnell I. Sevilla-Noarbe C. Smith M. Soares-Santos E. Suchyta M. E. C. Swanson G. Tarle J. Zuntz