DSpace Angular :: Browsing by Author "D'Ago, Giuseppe"

Browsing by Author "D'Ago, Giuseppe"

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Astroinformatics-based search for globular clusters in the Fornax Deep Survey
(2019) Angora, Giuseppe; Brescia, Massimo; Cavuoti, Stefano; Paolillo, M.; Longo, Giuseppe; Cantiello, M.; Capaccioli, M.; D'Abrusco, Raffaele; D'Ago, Giuseppe; Puzia, Thomas H.; Hilker, Michael; Iodice, Enrichetta; Mieske, Steffen; Napolitano, Nicola R.; Peletier, R.; Pota, Vincenzo; Riccio, Giuseppe; Spavone, Marilena
Building the Largest Spectroscopic Sample of Ultracompact Massive Galaxies with the Kilo Degree Survey
(IOP PUBLISHING LTD, 2020) Scognamiglio, Diana; Tortora, Crescenzo; Spavone, Marilena; Spiniello, Chiara; Napolitano, Nicola R.; D'Ago, Giuseppe; La Barbera, Francesco; Getman, Fedor; Roy, Nivya; Raj, Maria Angela; Radovich, Mario; Brescia, Massimo; Cavuoti, Stefano; Koopmans, Leon V. E.; Kuijken, Koen H.; Longo, Giuseppe; Petrillo, Carlo Enrico
Ultracompact massive galaxies (UCMGs), i.e., galaxies with stellar masses M. > 8 ' 1010M. and effective radii Re < 1.5 kpc, are very rare systems, in particular at low and intermediate redshifts. Their origin as well as their number density across cosmic time are still under scrutiny, especially because of the paucity of spectroscopically confirmed samples. We have started a systematic census of UCMG candidates within the ESO Kilo Degree Survey, together with a large spectroscopic follow-up campaign to build the largest possible sample of confirmed UCMGs. This is the third paper of the series and the second based on the spectroscopic follow-up program. Here, we present photometrical and structural parameters of 33 new candidates at redshifts 0.15. z. 0.5 and confirm 19 of them as UCMGs, based on their nominal spectroscopically inferred M. and Re. This corresponds to a success rate of 58%, nicely consistent with our previous findings. The addition of these 19 newly confirmed objects allows us to fully assess the systematics on the system selection-and to finally reduce the number density uncertainties. Moreover, putting together the results from our current and past observational campaigns and some literature data, we build the largest sample of UCMGs ever collected, comprising 92 spectroscopically confirmed objects at 0.1. z. 0.5. This number raises to 116, allowing for a 3s tolerance on the M. and Re thresholds for the UCMG definition. For all these galaxies, we have estimated the velocity dispersion values at the effective radii, which have been used to derive a preliminary mass-velocity dispersion correlation.
Central velocity dispersion catalogue of LAMOST-DR7 galaxies
(2020) Napolitano, Nicola R.; D'Ago, Giuseppe; Tortora, Crescenzo; Zhao, Gang; Luo, A-Li; Tang, Baitian; Zhang, Wei; Zhang, Yong; Li, Rui
The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) is a major facility to carry out spectroscopic surveys for cosmology and galaxy evolution studies. The seventh data release of the LAMOST ExtraGAlactic Survey (LEGAS) is currently available and including redshifts of 193 361 galaxies. These sources are spread over similar to 11 500 deg(2) of the sky, largely overlapping with other imaging (SDSS and HSC) and spectroscopic (BOSS) surveys. The estimated depth of the galaxy sample, r similar to 17.8, the high signal-to-noise ratio, and the spectral resolution R = 1800, make the LAMOST spectra suitable for galaxy velocity dispersion (VD) measurements, which are invaluable to study the structure and formation of galaxies and to determine their central dark matter content. We present the first estimates of central VD of similar to 86 000 galaxies in LAMOST footprint. We have used a wrap-up procedure to perform the spectral fitting using PPXF, and derive VD measurements. Statistical errors are also assessed by comparing LAMOST VD estimates with the ones of SDSS and BOSS over a common sample of similar to 51 000 galaxies. The two data sets show a good agreement, within the statistical errors, in particular when VD values are corrected to 1 effective radius aperture. We also present a preliminary mass-sigma relation and find consistency with previous analyses based on local galaxy samples. These first results suggest that LAMOST spectra are suitable for galaxy VD measurements to complement the available catalogues of galaxy internal kinematics in the Northern hemisphere. We plan to expand this analysis to next LAMOST data releases.
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.
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.
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.
Intrinsic Morphology of Ultra-diffuse Galaxies
(IOP PUBLISHING LTD, 2020) Rong, Yu; Dong, Xiao Yu; Puzia, Thomas H.; Galaz, Gaspar; Sanchez Janssen, Ruben; Cao, Tianwen; van der Burg, Remco F. J.; Sifon, Cristobal; Pina, Pavel E. Mancera; Marcelo, Mora; D'Ago, Giuseppe; Zhang, Hong Xin; Johnston, Evelyn J.; Eigenthaler, Paul
With the published data of apparent axis ratios for 1109 ultra-diffuse galaxies (UDGs) located in 17 low-redshift (z similar to 0.020-0.063) galaxy clusters and 84 UDGs in two intermediate-redshift (z similar to 0.308-0.348) clusters, we take advantage of a Markov Chain Monte Carlo approach and assume a triaxial model to investigate the intrinsic morphologies of UDGs. In contrast to the conclusion of Burkert, i.e., the underlying shapes of UDGs are purely prolate (C = B < A), we find that the data favor the oblate-triaxial models (i.e., thick disks with C < B less than or similar to A) over the nearly prolate ones. We also find that the intrinsic morphologies of UDGs are related to their stellar masses/luminosities, environments, and redshifts. First, the more luminous UDGs have puffier morphologies compared with the less luminous counterparts; the UDG morphologic dependence on luminosity is distinct from that of the typical quiescent dwarf ellipticals (dEs) and dwarf spheroidals (dSphs); in this sense, UDGs may not be simply treated as an extension of the dE/dSph class with similar evolutionary histories; they may differ not only in size. Second, the UDGs with smaller clustercentric distances are more puffed up, compared with the counterparts with larger clustercentric distances; in combination with the UDG thickness dependence on luminosity, the puffier morphologies of UDGs with high luminosities or located in the denser environments are very likely to be attributed to tidal interactions with massive galaxies. Third, we find that the intermediate-redshift UDGs are more flattened, compared with the low-redshift counterparts, which plausibly suggests a "disky" origin for the high-redshift, newly born UDGs.
Nature versus nurture : relic nature and environment of the most massive passive galaxies at z < 0.5
(2020) Tortora, C.; Napolitano, N. R.; Radovich, M.; Spiniello, C.; Hunt, L.; Roy, N.; Moscardini, L.; Scognamiglio, D.; Spavone, M.; D'Ago, Giuseppe; Cavuoti, S.; Longo, G.; Bellagamba, F.; Maturi, M.; Roncarelli, M.
OGLE-2013-BLG-0911Lb : A Secondary on the Brown-dwarf Planet Boundary around an M Dwarf
(2020) Miyazaki, S; Sumi, T; Bennett, DP; Udalski, A; Shvartzvald, Y; Street, R; Bozza, V; Yee, JC; Rabus, Markus; D'Ago, Giuseppe; Bond, IA; Rattenbury, N; Koshimoto, N; Suzuki, D; Fukui, A; Abe, F; Bhattacharya, A; Barry, R; Donachie, M; Fujii, H; Hirao, Y; Itow, Y; Kamei, Y; Kondo, I; Li, MCA; Ling, CH; Matsubara, Y; Matsuo, T; Muraki, Y; Nagakane, M; Ohnishi, K; Ranc, C; Saito, T; Sharan, A; Shibai, H; Suematsu, H; Sullivan, DJ; Tristram, PJ; Yamakawa, T; Yonehara, A; Skowron, J; Poleski, R; Mroz, P; Szymanski, MK; Soszynski, I; Pietrukowicz, Pawel; KozLowski, S; Ulaczyk, K; Wyrzykowski, L; Friedmann, M; Kaspi, S; Maoz, D; Albrow, M; Christie, G; DePoy, DL; Gal-Yam, A; Gould, A; Lee, CU; Manulis, I; McCormick, J; Natusch, T; Ngan, H; Pogge, RW; Porritt, I; Tsapras, Y; Bachelet, E; Hundertmark, MPG; Dominik, M; Bramich, DM; Cassan, A; Jaimes, RF; Horne, K; Schmidt, R; Snodgrass, C; Wambsganss, J; Steele, IA; Menzies, J; Mao, S; Jorgensen, UG; Burgdorf, MJ; Ciceri, S; Novati, SC; Evans, DF; Hinse, TC; Kains, N; Kerins, E; Korhonen, H; Mancini, L; Popovas, A; Rahvar, S; Scarpetta, G; Skottfelt, J; Southworth, J; Peixinho, N; Verma, P
OGLE-2019-BLG-0825: Constraints on the Source System and Effect on Binary-lens Parameters Arising from a Five-day Xallarap Effect in a Candidate Planetary Microlensing Event
(2023) Satoh, Yuki; Koshimoto, Naoki; Bennett, David A.; Sumi, Takahiro; Rattenbury, Nicholas; Suzuki, Daisuke; Miyazaki, Shota; Bond, Ian; Udalski, Andrzej; Gould, Andrew; Bozza, Valerio; Dominik, Martin; Hirao, Yuki; Kondo, Iona; Kirikawa, Rintaro; Hamada, Ryusei; Abe, Fumio; Barry, Richard; Bhattacharya, Aparna; Fujii, Hirosane; Fukui, Akihiko; Fujita, Katsuki; Ikeno, Tomoya; Ishitani Silva, Stela; Itow, Yoshitaka; Matsubara, Yutaka; Matsumoto, Sho; Muraki, Yasushi; Niwa, Kosuke; Okamura, Arisa J.; Olmschenk, Greg; Ranc, Clement; Toda, Taiga; Tomoyoshi, Mio; Tristram, Paul; Vandorou, Aikaterini; Yama, Hibiki; Yamashita, Kansuke; Mroz, Przemek; Poleski, Radoslaw; Skowron, Jan; Szymanski, Michal K.; Poleski, Radek A.; Soszynski, Igor; Pietrukowicz, Pawel; Kozlowski, Szymon; Ulaczyk, Krzysztof D.; Rybicki, Krzysztof; Iwanek, Patryk; Wrona, Marcin; Gromadzki, Mariusz; Albrow, Michael; Chung, Sun-Ju; Han, Cheongho; Hwang, Kyu-Ha; Kim, Doeon; Jung, Youn Kil; Kim, Hyoun Woo C.; Ryu, Yoon-Hyun; Shin, In-Gu; Shvartzvald, Yossi; Yang, Hongjing; Yee, Jennifer; Zang, Weicheng; Cha, Sang-Mok; Kim, Dong-Jin; Kim, Seung-Lee W.; Lee, Chung-Uk G.; Lee, Dong-Joo; Lee, Yongseok; Park, Byeong-Gon; Pogge, Richard; Jorgensen, Uffe; Longa-Pena, Penelope; Sajadian, Sedighe; Skottfelt, Jesper; Snodgrass, Colin; Tregloan-Reed, Jeremy; Bach-Moller, Nanna; Burgdorf, Martin; D'Ago, Giuseppe; Haikala, Lauri; Hitchcock, James; Hundertmark, Markus; Khalouei, Elahe; Peixinho, Nuno; Rahvar, Sohrab; Southworth, John; Spyratos, Petros
We present an analysis of microlensing event OGLE-2019-BLG-0825. This event was identified as a planetary candidate by preliminary modeling. We find that significant residuals from the best-fit static binary-lens model exist and a xallarap effect can fit the residuals very well and significantly improves chi (2) values. On the other hand, by including the xallarap effect in our models, we find that binary-lens parameters such as mass ratio, q, and separation, s, cannot be constrained well. However, we also find that the parameters for the source system such as the orbital period and semimajor axis are consistent between all the models we analyzed. We therefore constrain the properties of the source system better than the properties of the lens system. The source system comprises a G-type main-sequence star orbited by a brown dwarf with a period of P similar to 5 days. This analysis is the first to demonstrate that the xallarap effect does affect binary-lens parameters in planetary events. It would not be common for the presence or absence of the xallarap effect to affect lens parameters in events with long orbital periods of the source system or events with transits to caustics, but in other cases, such as this event, the xallarap effect can affect binary-lens parameters.
The elemental abundance of quiescent galaxies in the LEGA-C survey: the (non-)evolution of [α/Fe] from z=0.75 to z=0
(2023) Bevacqua, Davide; Saracco, Paolo; La Barbera, Francesco; D'Ago, Giuseppe; De Propris, Roberto; Ferreras, Ignacio; Gallazzi, Anna; Pasquali, Anna; Spiniello, Chiara
We measure the [alpha/Fe] abundances for 183 quiescent galaxies at z = 0.60-0.75 with stellar masses ranging 10.4 <= log(10)(M-*/M-circle dot) <= 11.6 selected from the Large Early Galaxy Astrophysics Census survey. We estimate [alpha/Fe] from the ratio of the spectral indices Mgb (lambda similar to 5177 angstrom) and Fe4383, compared to predictions of simple stellar population models. We find that 91 percent of quiescents in our sample have supersolar [alpha/Fe], with an average value of [alpha/Fe] = +0.24 +/- 0.01. We find no significant correlation between [alpha/Fe] and stellar metallicity, mass, velocity dispersion, and average formation time. Galaxies that formed the bulk of their stellar mass on time-scales shorter than 1 Gyr follow the same [alpha/Fe] distribution as those which formed on longer time-scales. In comparison to local early-type galaxies and to stacked spectra of quiescent galaxies at z = 0.38 and z = 0.07, we find that the average [alpha/Fe] has not changed between z = 0.75 and the present time. Our work shows that the vast majority of massive quiescent galaxies at z similar to 0.7 are alpha-enhanced, and that no detectable evolution of the average [alpha/Fe] has taken place over the last similar to 6.5 Gyr.
Transit timing variations in the WASP-4 planetary system
(2019) Southworth, J.; Dominik, M.; Jorgensen, U. G.; Andersen, M. I.; Bozza, V.; Burgdorf, M. J.; D'Ago, Giuseppe; Dib, S.; Jaimes, R. F.; Fujii, Y. I.; Gill, S.; Haikala, L. K.; Hinse, T. C.; Hundertmark, M.; Khalouei, E.; Korhonen, H.; Longa Pena, P.; Mancini, L.; Peixinho, N.; Rabus, Markus; Rahvar, S.; Sajadian, S.; Skottfelt, J.; Snodgrass, C.; Spyratos, P.; Tregloan Reed, J.; Unda Sanzana, E.; Von Essen, C.
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).

Browsing by Author "D'Ago, Giuseppe"

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