Browsing by Author "Paolillo, Maurizio"

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    Formation of an ultra-diffuse galaxy in the stellar filaments of NGC 3314A: Caught in the act?
    (2021) Iodice, Enrichetta; La Marca, Antonio; Hilker, Michael; Cantiello, Michele; D'Ago, Giuseppe; Gullieuszik, Marco; Rejkuba, Marina; Arnaboldi, Magda; Spavone, Marilena; Spiniello, Chiara; Forbes, Duncan A.; Greggio, Laura; Rampazzo, Roberto; Mieske, Steffen; Paolillo, Maurizio; Schipani, Pietro
    The VEGAS imaging survey of the Hydra I cluster has revealed an extended network of stellar filaments to the south-west of the spiral galaxy NGC 3314A. Within these filaments, at a projected distance of similar to 40 kpc from the galaxy, we discover an ultra-diffuse galaxy (UDG) with a central surface brightness of mu(0,g) similar to 26 mag arcsec(-2) and effective radius R-e similar to 3.8 kpc. This UDG, named UDG 32, is one of the faintest and most diffuse low-surface-brightness galaxies in the Hydra I cluster. Based on the available data, we cannot exclude that this object is just seen in projection on top of the stellar filaments and is thus instead a foreground or background UDG in the cluster. However, the clear spatial coincidence of UDG 32 with the stellar filaments of NGC 3314A suggests that it might have formed from the material in the filaments, becoming a detached, gravitationally bound system. In this scenario, the origin of UDG 32 depends on the nature of the stellar filaments in NGC 3314A, which is still unknown. The stellar filaments could result from ram-pressure stripping or have a tidal origin. In this letter we focus on the comparison of the observed properties of the stellar filaments and of UDG 32 and speculate on their possible origin. The relatively red colour (g - r=0.54 +/- 0.14 mag) of the UDG, similar to that of the disk in NGC 3314A, combined with an age older than 1 Gyr and the possible presence of a few compact stellar systems, points towards a tidal formation scenario.
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    Galaxy populations in the Hydra I cluster from the VEGAS survey I. Optical properties of a large sample of dwarf galaxies
    (2022) La Marca, Antonio; Peletier, Reynier; Iodice, Enrichetta; Paolillo, Maurizio; Challapa, Nelvy Choque; Venhola, Aku; Forbes, Duncan A.; Cantiello, Michele; Hilker, Michael; Rejkuba, Marina; Arnaboldi, Magda; Spavone, Marilena; D'Ago, Giuseppe; Raj, Maria Angela; Ragusa, Rossella; Mirabile, Marco; Rampazzo, Roberto; Spiniello, Chiara; Mieske, Steffen; Schipani, Pietro
    Context. Due to their relatively low stellar mass content and diffuse nature, the evolution of dwarf galaxies can be strongly affected by their environment. Analyzing the properties of the dwarf galaxies over a wide range of luminosities, sizes, morphological types, and environments, we can obtain insights about their evolution. At similar to 50 Mpc, the Hydra I cluster of galaxies is among the closest cluster in the z similar or equal to 0 Universe, and an ideal environment to study dwarf galaxy properties in a cluster environment.
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    Galaxy populations in the Hydra I cluster from the VEGAS survey II. The ultra-diffuse galaxy population
    (2022) La Marca, Antonio; Iodice, Enrichetta; Cantiello, Michele; Forbes, Duncan A.; Rejkuba, Marina; Hilker, Michael; Arnaboldi, Magda; Greggio, Laura; Spiniello, Chiara; Mieske, Steffen; Venhola, Aku; Spavone, Marilena; D'Ago, Giuseppe; Raj, Maria Angela; Ragusa, Rossella; Mirabile, Marco; Rampazzo, Roberto; Peletier, Reynier; Paolillo, Maurizio; Challapa, Nelvy Choque; Schipani, Pietro
    In this work, we extend the catalog of low-surface brightness (LSB) galaxies, including ultra-diffuse galaxy (UDG) candidates, within approximate to 0.4R(vir) of the Hydra I cluster of galaxies based on deep images from the VST Early-type GAlaxy Survey (VEGAS). The new galaxies were found by applying an automatic detection tool and carrying out additional visual inspections of g and r band images. This led to the detection of 11 UDGs and 8 more LSB galaxies. For all of them, we assessed the cluster membership using the color-magnitude relation derived for early-type giant and dwarf galaxies in Hydra I. The UDGs and new LSB galaxies found in Hydra I span a wide range of central surface brightness (22.7 less than or similar to mu(0.g) less than or similar to 26.5 mag arcse(-2)), effective radius (0.6 less than or similar to R-e less than or similar to 4.0 kpc), and color (0.4 <= g-r <= 0.9 mag), and have stellar masses in the range similar to 5 x 10(6)-2 x 10(8) M-circle dot. The 2D projected distribution of both galaxy types is similar to the spatial distribution of dwarf galaxies, with over-densities in the cluster core and north of the cluster center. They have similar color distribution and comparable stellar masses to the red dwarf galaxies. Based on photometric selection, we identify a total of nine globular cluster (GC) candidates associated to the UDGs and four to the LSB galaxies, with the highest number of candidates in an individual UDG being three. We find that there are no relevant differences between dwarfs, LSB galaxies, and UDGs: the structural parameters (i.e., surface brightness, size, color, and n-index) and GC content of the three classes have similar properties and trends. This finding is consistent with UDGs being the extreme LSB tail of the size-luminosity distribution of dwarfs in this environment.
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    The Fornax Cluster VLT Spectroscopic Survey III. Kinematical characterisation of globular clusters in the Fornax galaxy cluster
    (2022) Chaturvedi, Avinash; Hilker, Michael; Cantiello, Michele; Napolitano, Nicola R.; van de Ven, Glenn; Spiniello, Chiara; Fahrion, Katja; Paolillo, Maurizio; Gatto, Massimiliano; Puzia, Thomas
    The Fornax cluster provides an unparalleled opportunity of investigating the formation and evolution of early-type galaxies in a dense environment in detail. We aim at kinematically characterising photometrically detected globular cluster (GC) candidates in the core of the cluster. We used spectroscopic data from the Visible Multi Object Spectrograph at Very Large Telescope (VLT/VIMOS) from the FVSS survey in the Fornax cluster, covering one square degree around the central massive galaxy NGC 1399. We confirm a total of 777 GCs, almost doubling previously detected GCs, using the same dataset as was used before. Combined with previous literature radial velocity measurements of GCs in Fornax, we compile the most extensive spectroscopic GC sample of 2341 objects in this environment. We found that red GCs are mostly concentrated around major galaxies, while blue GCs are kinematically irregular and are widely spread throughout the core region of the cluster. The velocity dispersion profiles of blue and red GCs show a quite distinct behaviour. Blue GCs exhibit a sharp increase in the velocity dispersion profile from 250 to 400 km s(-1) within 5 arcmin (similar to 29 kpc/similar to 1 r(eff) of NGC 1399) from the central galaxy. The velocity dispersion profile of red GCs follows a constant value between 200 and 300 km s(-1) until 8 arcmin (similar to 46 kpc/similar to 1.6 r(eff)), and then rises to 350 km s(-1) at 10 arcmin (similar to 58 kpc/similar to 2 r(eff)). Beyond 10 arcmin and out to 40 arcmin (similar to 230 kpc/ similar to 8 r(eff)), blue and red GCs show a constant velocity dispersion of 300 +/- 50 km s(-1), indicating that both GC populations trace the cluster potential. We kinematically confirm and characterise the previously photometrically discovered overdensities of intra-cluster GCs. We found that these substructured intra-cluster regions in Fornax are dominated mostly by blue GCs.
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    The XMM-SERVS Survey: XMM-Newton Point-source Catalogs for the W-CDF-S and ELAIS-S1 Fields
    (2021) Ni, Qingling; Brandt, W. N.; Chen, Chien-Ting; Luo, Bin; Nyland, Kristina; Yang, Guang; Zou, Fan; Aird, James; Alexander, David M.; Bauer, Franz Erik; Lacy, Mark; Lehmer, Bret D.; Mallick, Labani; Salvato, Mara; Schneider, Donald P.; Tozzi, Paolo; Traulsen, Iris; Vaccari, Mattia; Vignali, Cristian; Vito, Fabio; Xue, Yongquan; Banerji, Manda; Chow, Kate; Comastri, Andrea; Del Moro, Agnese; Gilli, Roberto; Mullaney, James; Paolillo, Maurizio; Schwope, Axel; Shemmer, Ohad; Sun, Mouyuan; Timlin III, John D.; Trump, Jonathan R.
    We present the X-ray point-source catalogs in two of the XMM-Spitzer Extragalactic Representative Volume Survey (XMM-SERVS) fields, W-CDF-S (4.6 deg(2)) and ELAIS-S1 (3.2 deg(2)), aiming to fill the gap between deep pencil-beam X-ray surveys and shallow X-ray surveys over large areas. The W-CDF-S and ELAIS-S1 regions were targeted with 2.3 and 1.0 Ms of XMM-Newton observations, respectively; 1.8 and 0.9 Ms exposures remain after flare filtering. The survey in W-CDF-S has a flux limit of 1.0 x 10(-14) erg cm(-2) s(-1) over 90% of its area in the 0.5-10 keV band; 4053 sources are detected in total. The survey in ELAIS-S1 has a flux limit of 1.3 x 10(-14) erg cm(-2) s(-1) over 90% of its area in the 0.5-10 keV band; 2630 sources are detected in total. Reliable optical-to-IR multiwavelength counterpart candidates are identified for approximate to 89% of the sources in W-CDF-S and approximate to 87% of the sources in ELAIS-S1. A total of 3129 sources in W-CDF-S and 1957 sources in ELAIS-S1 are classified as active galactic nuclei (AGNs). We also provide photometric redshifts for X-ray sources; approximate to 84% of the 3319/2001 sources in W-CDF-S/ELAIS-S1 with optical-to-near-IR forced photometry available have either spectroscopic redshifts or high-quality photometric redshifts. The completion of the XMM-Newton observations in the W-CDF-S and ELAIS-S1 fields marks the end of the XMM-SERVS survey data gathering. The approximate to 12,000 pointlike X-ray sources detected in the whole approximate to 13 deg(2) XMM-SERVS survey will benefit future large-sample AGN studies.
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    VEGAS-SSS. A VST early-type galaxy survey: analysis of small stellar systems Testing the methodology on the globular cluster system in NGC 3115
    (2015) Cantiello, Michele; Capaccioli, Massimo; Napolitano, Nicola; Grado, Aniello; Limatola, Luca; Paolillo, Maurizio; Iodice, Enrica; Romanowsky, Aaron J.; Forbes, Duncan A.; Puzia, Thomas H.; Spavone, Marilena; La Barbera, Francesco; Raimondo, Gabriella; Schipani, Pietro
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    VEGAS: A VST Early-type GAlaxy Survey: VI. Diffuse light in HCG 86 as seen from the ultra-deep VEGAS images
    (2021) Ragusa, Rossella; Spavone, Marilena; Iodice, Enrichetta; Brough, Sarah; Raj, Maria Angela; Paolillo, Maurizio; Cantiello, Michele; Forbes, Duncan A.; La Marca, Antonio; D'Ago, Giuseppe; Rampazzo, Roberto; Schipani, Pietro
    Context. In this paper, we present ultra-deep images of the compact group of galaxies HCG 86 as part of the VEGAS survey.Aims. Our main goals are to estimate the amount of intra-group light (IGL) as well as to study the light and colour distributions in order to address the main formation process of the IGL component in groups of galaxies.Methods. We derived the azimuthally averaged surface brightness profiles in the g, r, and i bands with g-r and r-i average colours and colour profiles for all group members. By fitting the light distribution, we extrapolated the contribution of the stellar halos plus the diffuse light from the brightest component of each galaxy. The results are compared with theoretical predictions.Results. The long integration time and wide area covered make our data reach deeper than previous literature studies of the IGL in compact groups of galaxies and allow us to produce an extended (similar to 160 kpc) map of the IGL, down to a surface brightness level of similar to 30 mag arcsec(-2) in the g band. The IGL in HCG 86 is mainly in diffuse form and has average colours of g-r similar to 0.8 mag and r-i similar to 0.4 mag. The fraction of IGL in HCG 86 is similar to 16% of the total luminosity of the group, and this is consistent with estimates available for other compact groups and loose groups of galaxies of similar virial masses. A weak trend is present between the amount of IGL and the early-type to late-type galaxy ratio. A lack of a clear correlation is found between the amount of diffuse light and the cluster or group virial mass.Conclusions. By comparing the IGL fraction and colours with those predicted by simulations, the amount of IGL in HCG 86 would be the result of the disruption of satellites at an epoch of z similar to 0.4. At this redshift, the observed colours are consistent with the scenario where the main contribution to the mass of the IGL comes from the intermediate-to-massive galaxies (10(10)<= M-*<= 10(11) M-circle dot).
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    Wide-field hubble space telescope observations of the globular cluster system in NGC 1399
    (2014) Puzia, Thomas H.; Paolillo, Maurizio; Goudfrooij, Paul; Maccarone, Thomas J.; Fabbiano, Giuseppina; Angelini, Lorella