The large-scale structure of globular clusters in the NGC 1052 group

Prompted by the many controversial claims involving the NGC 1052 group, including that it hosts two dark matter-free galaxies with overluminous and monochromatic globular cluster (GC) systems, here we map out the large-scale structure (LSS) of GCs over the entire group. To recover the LSS, we use archival optical CFHT imaging data. We recover two GC density maps, one based on universal photometric properties of GCs from simple stellar population models, and one based on the properties of spectroscopically confirmed GCs in DF2 and DF4 (the two dwarf galaxies with overluminous GC populations). Both selection methods reveal overdensities around the massive galaxies in the group, as well as around NGC 1052 itself, that are coincident with the positions of previously identified stellar streams and tidal features. No intragroup GCs are found connecting these structures to any of the dwarf galaxies. We find, however, two other dwarfs in the group hosting GC systems. These include RCP32 with 2 GCs with ages equivalent to the GCs around NGC 1052, and DF9 with 3 GCs with ages similar to the GCs around DF2 and DF4. We conclude that the GC distribution in the group does not strongly support any formation scenario in particular. It favours, nonetheless, scenarios relying on galaxy-galaxy interactions and on the coeval formation of GCs around the DM-free dwarf galaxies. These may include the recently proposed bullet-dwarf formation, as well as high-redshift tidal dwarf galaxy models.Comment: Accepted for publication in MNRAS. 11 pages, 5 figures, 2 table

The stellar populations of quiescent ultra-diffuse galaxies from optical to mid-infrared spectral energy distribution fitting

We use spectral energy distribution (SED) fitting to place constraints on the stellar population properties of 29 quiescent ultra-diffuse galaxies (UDGs) across different environments. We use the fully Bayesian routine PROSPECTOR coupled with archival data in the optical, near, and mid-infrared from Spitzer and Wide-field Infrared Survey Explorer under the assumption of an exponentially declining star formation history. We recover the stellar mass, age, metallicity, dust content, star formation time scales, and photometric redshifts (photo-zs) of the UDGs studied. Using the mid-infrared data, we probe the existence of dust in UDGs. Although its presence cannot be confirmed, we find that the inclusion of small amounts of dust in the models brings the stellar populations closer to those reported with spectroscopy. Additionally, we fit the redshifts of all galaxies. We find a high accuracy in recovering photo-zs compared to spectroscopy, allowing us to provide new photo-z estimates for three field UDGs with unknown distances. We find evidence of a stellar population dependence on the environment, with quiescent field UDGs being systematically younger than their cluster counterparts. Lastly, we find that all UDGs lie below the mass–metallicity relation for normal dwarf galaxies. Particularly, the globular cluster (GC)-poor UDGs are consistently more metal-rich than GC-rich ones, suggesting that GC-poor UDGs may be puffed-up dwarfs, while most GC-rich UDGs are better explained by a failed galaxy scenario. As a byproduct, we show that two galaxies in our sample, NGC 1052-DF2 and NGC 1052-DF4, share equivalent stellar population properties, with ages consistent with 8 Gyr. This finding supports formation scenarios where the galaxies were formed together

A candidate runaway supermassive black hole identified by shocks and star formation in its wake

The interaction of a runaway supermassive black hole (SMBH) with the circumgalactic medium (CGM) can lead to the formation of a wake of shocked gas and young stars behind it. Here we report the serendipitous discovery of an extremely narrow linear feature in HST/ACS images that may be an example of such a wake. The feature extends 62 kpc from the nucleus of a compact star-forming galaxy at z=0.964. Keck LRIS spectra show that the [OIII]/H$\beta$ ratio varies from ~1 to ~10 along the feature, indicating a mixture of star formation and fast shocks. The feature terminates in a bright [OIII] knot with a luminosity of 1.9x10$^{41}$ ergs/s. The stellar continuum colors vary along the feature, and are well-fit by a simple model that has a monotonically increasing age with distance from the tip. The line ratios, colors, and the overall morphology are consistent with an ejected SMBH moving through the CGM at high speed while triggering star formation. The best-fit time since ejection is ~39 Myr and the implied velocity is v~1600 km/s. The feature is not perfectly straight in the HST images, and we show that the amplitude of the observed spatial variations is consistent with the runaway SMBH interpretation. Opposite the primary wake is a fainter and shorter feature, marginally detected in [OIII] and the rest-frame far-ultraviolet. This feature may be shocked gas behind a binary SMBH that was ejected at the same time as the SMBH that produced the primary wake.Comment: Accepted for publication in ApJ Letters. The key data are in Figure 1: a really odd thin streak in HST images, with a complex emission line spectrum. Figure 7 is an illustration of our proposed interpretatio

Recovering the origins of the lenticular galaxy NGC 3115 using multiband imaging

A detailed study of the morphology of lenticular galaxies is an important way to understand how this type of galaxy is formed and evolves over time. Decomposing a galaxy into its components (disc, bulge, bar, ...) allows recovering the colour gradients present in each system, its star formation history, and its assembly history. We use GALFITM to perform a multiwavelength structural decomposition of the closest lenticular galaxy, NGC 3115, resulting in the description of its stellar light into several main components: a bulge, a thin disc, a thick disc, and also evidence of a bar. We report the finding of central bluer stellar populations in the bulge, as compared to the colour of the galaxy outskirts, indicating either the presence of an active galactic nucleus (AGN) and/or recent star formation activity. From the spectral energy distribution results, we show that the galaxy has a low luminosity AGN component, but even excluding the effect of the nuclear activity, the bulge is still bluer than the outer-regions of the galaxy, revealing a recent episode of star formation. Based on all of the derived properties, we propose a scenario for the formation of NGC 3115 consisting of an initial gas-rich merger, followed by accretions and feedback that quench the galaxy, until a recent encounter with the companion KK084 that reignited the star formation in the bulge, provoked a core displacement in NGC 3115 and generated spiral-like features. This result is consistent with the two-phase formation scenario, proposed in previous studies of this galaxy

A new method to detect globular clusters with the S-PLUS survey

In this paper, we describe a new method to select globular cluster (GC) candidates, including galaxy subtraction with unsharp masking, template fitting techniques, and the inclusion of Gaia’s proper motions. We report the use of the 12-band photometric system used by S-PLUS to determine radial velocities and stellar populations of GCs around nearby galaxies. Specifically, we assess the effectiveness of identifying GCs around nearby and massive galaxies (D 200 km s-1) in a multiband survey such as S-PLUS by using spectroscopically confirmed GCs and literature GC candidate lists around the bright central galaxy in the Fornax cluster, NGC 1399 (D = 19 Mpc), and the isolated lenticular galaxy NGC 3115 (D = 9.4 Mpc). Despite the shallow survey depth, which limits this work to r < 21.3 mag, we measure reliable photometry and perform robust SED fitting for a sample of 115 GCs around NGC 1399 and 42 GCs around NGC 3115, recovering radial velocities, ages, and metallicities for the GC populations. © 2021 The Author(s).MLB and CMdO acknowledge the financial support of the Sao Paulo Research Foundation (FAPESP) under grant 2019/23388-0. CEB acknowledges FAPESP, grant2016/12331-0. PC acknowledges support from Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) under grant 310041/2018-0. DdBS also acknowledges Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) process number 2017/00204-6 for the financial support. AC-S acknowledge funding from the brazilian agencies Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) and the Fundação de Amparo à Pesquisa do Estado do RS (FAPERGS) through grants CNPq-403580/2016-1, CNPq-11153/2018-6, PqG/FAPERGS-17/2551-0001, FAPERGS/CAPES 19/2551-0000696-9, L’Oréal UNESCO ABC Para Mulheres na Ciência and the Chinese Academy of Sciences (CAS) President’s International Fellowship Initiative (PIFI) through grant E085201009. AA-C acknowledges support from the State Agency for Research of the Spanish MCIU through the ‘Center of Excellence Severo Ochoa’ award to the Instituto de Astrofísica de Andalucía (SEV-2017-0709). This work was funded with grants from Consejo Nacional de Investigaciones Científicas y Técnicas and Universidad Nacional de La Plata (Argentina). The S-PLUS project, including the T80-South robotic telescope and the S-PLUS scientific survey, was founded as a partnership between the Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP), the Observatório Nacional (ON), the Federal University of Sergipe (UFS), and the Federal University of Santa Catarina (UFSC), with important financial and practical contributions from other collaborating institutes in Brazil, Chile (Universidad de La Serena), and Spain (Centro de Estudios de Física del Cosmos de Aragón, CEFCA). We further acknowledge financial support from the São Paulo Research Foundation (FAPESP), the Brazilian National Research Council (CNPq), the Coordination for the Improvement of Higher Education Personnel (CAPES), the Carlos Chagas Filho Rio de Janeiro State Research Foundation (FAPERJ), and the Brazilian Innovation Agency (FINEP). The authors are grateful for the contributions from CTIO staff in helping in the construction, commissioning, and maintenance of the T80-South telescope and camera. We are also indebted to Rene Laporte and INPE, as well as Keith Taylor, for their important contributions to the project. We also thank CEFCA staff for their help with T80-South, specifically we thank Antonio Marín-Franch for his invaluable contributions in the early phases of the project, David Cristóbal-Hornillos and his team for their help with the installation of the data reduction package jype version 0.9.9, César Íãiguez for providing 2D measurements of the filter transmissions, and all other staff members for their support.Peer reviewe

A new method to detect globular clusters with the S-PLUS survey

In this paper, we describe a new method to select globular cluster (GC) candidates, including galaxy subtraction with unsharp masking, template fitting techniques, and the inclusion of Gaia’s proper motions. We report the use of the 12-band photometric system used by S-PLUS to determine radial velocities and stellar populations of GCs around nearby galaxies. Specifically, we assess the effectiveness of identifying GCs around nearby and massive galaxies (D 200 km s-1) in a multiband survey such as S-PLUS by using spectroscopically confirmed GCs and literature GC candidate lists around the bright central galaxy in the Fornax cluster, NGC 1399 (D = 19 Mpc), and the isolated lenticular galaxy NGC 3115 (D = 9.4 Mpc). Despite the shallow survey depth, which limits this work to r < 21.3 mag, we measure reliable photometry and perform robust SED fitting for a sample of 115 GCs around NGC 1399 and 42 GCs around NGC 3115, recovering radial velocities, ages, and metallicities for the GC populations. © 2021 The Author(s).MLB and CMdO acknowledge the financial support of the Sao Paulo Research Foundation (FAPESP) under grant 2019/23388-0. CEB acknowledges FAPESP, grant2016/12331-0. PC acknowledges support from Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) under grant 310041/2018-0. DdBS also acknowledges Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) process number 2017/00204-6 for the financial support. AC-S acknowledge funding from the brazilian agencies Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) and the Fundação de Amparo à Pesquisa do Estado do RS (FAPERGS) through grants CNPq-403580/2016-1, CNPq-11153/2018-6, PqG/FAPERGS-17/2551-0001, FAPERGS/CAPES 19/2551-0000696-9, L’Oréal UNESCO ABC Para Mulheres na Ciência and the Chinese Academy of Sciences (CAS) President’s International Fellowship Initiative (PIFI) through grant E085201009. AA-C acknowledges support from the State Agency for Research of the Spanish MCIU through the ‘Center of Excellence Severo Ochoa’ award to the Instituto de Astrofísica de Andalucía (SEV-2017-0709). This work was funded with grants from Consejo Nacional de Investigaciones Científicas y Técnicas and Universidad Nacional de La Plata (Argentina). The S-PLUS project, including the T80-South robotic telescope and the S-PLUS scientific survey, was founded as a partnership between the Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP), the Observatório Nacional (ON), the Federal University of Sergipe (UFS), and the Federal University of Santa Catarina (UFSC), with important financial and practical contributions from other collaborating institutes in Brazil, Chile (Universidad de La Serena), and Spain (Centro de Estudios de Física del Cosmos de Aragón, CEFCA). We further acknowledge financial support from the São Paulo Research Foundation (FAPESP), the Brazilian National Research Council (CNPq), the Coordination for the Improvement of Higher Education Personnel (CAPES), the Carlos Chagas Filho Rio de Janeiro State Research Foundation (FAPERJ), and the Brazilian Innovation Agency (FINEP). The authors are grateful for the contributions from CTIO staff in helping in the construction, commissioning, and maintenance of the T80-South telescope and camera. We are also indebted to Rene Laporte and INPE, as well as Keith Taylor, for their important contributions to the project. We also thank CEFCA staff for their help with T80-South, specifically we thank Antonio Marín-Franch for his invaluable contributions in the early phases of the project, David Cristóbal-Hornillos and his team for their help with the installation of the data reduction package jype version 0.9.9, César Íãiguez for providing 2D measurements of the filter transmissions, and all other staff members for their support.Peer reviewe

Estudos detalhados de galáxias lenticulares no universo local

S0 galaxies are supposedly a transitional stage in the life of a galaxy, in which it shares properties of both elliptical and spiral galaxies. Thus, understanding this type of object can bring important information on the whole field of galaxy evolution. Lenticular galaxies account for almost half of the giant galaxy population in the nearby universe, yet their formation history and whether they are a unique or a composite class of objects remain an open question of modern astronomy. In this work, we study this class of galaxies in three fronts using different datasets: firstly, we look at a fully formed lenticular galaxy, NGC 3115, using multi-wavelength data to recover its formation history and evolution; secondly, we look at an event that could generate an S0, the major merger NGC 1487, using MUSE/VLT integral field spectroscopy (IFS) data. Finally, we study the distribution of S0 galaxies in the local universe using photometric data from the S-PLUS survey. Putting together these three works, we aim at providing a better understanding of lenticular galaxies in the local universe and at identifying what are the progenitors and the most likely formation scenarios in different environments. In the Hubble classification scheme, lenticular galaxies are defined to have a disk, without spiral arms. Yet a more detailed study reveals that lenticulars present several subcomponents, as a disk, a bulge, and in some cases also a bar and lenses. Decomposing a galaxy in its components allows recovering the colour gradients present in the system, its star formation history and, finally, its assembly history. We used GALFITM to perform a multi-wavelength structural decomposition of the closest lenticular galaxy to the MW, NGC 3115, resulting in the description of its stellar populations into three main components, including a bulge, a thin disk and a thick disk. We recovered pixelized color-magnitude diagrams and the spectral energy distribution of the components. The results show that the majority of the mass of the galaxy is in the bulge region and that this is the bluest component, suggesting both active galactic nuclei (AGN) activity and recent star formation events. We show that this galaxy holds a bar and central spiral-like features, probably created during a recent interaction. Finally, we propose a scenario for the formation of NGC 3115 based on an initial gas-rich merger, followed by a sequence of accretions and AGN feedback, responsible for quenching the galaxy, until a recent encounter reignited the star formation in the bulge and generated the observed spiral features. It is well known that S0 galaxies can be formed by different processes, here we study the effectiveness of major mergers as one of the formation mechanisms of S0 galaxies. Using MUSE/VLT IFU data of the major merger NGC 1487, we study the physical and kinematical properties of the system. We find an inversion in the metallicity gradient of the system NGC1487, explained by metal mixing processes. The velocity field revealed a rotating pattern in one of the sub-components of NGC1487, showing that the galaxy may be in the process of recreating a disc. We conclude that if the evolution of the system would lead to the formation of a disc, then this merger event could evolve passively to become an S0 galaxy in several Gyr from now. Finally, to understand the distribution of lenticular galaxies in the local universe, and the role of environments in their formation, we determined photometric redshifts and spectral types for galaxies in the S-PLUS survey. We identified the objects best-fitted by the lenticular galaxies template and found their distribution across the local universe. The results show that S0s mostly lie in clustered regions and are hardly isolated. Moreover, we show that among galaxies identified as lenticular according to their spectral-type, the ones with low star formation rates also present a visual morphology typical of lenticular galaxies, while those with high star formation rates are probably lenticular galaxies with nuclear activity or incorrectly classified spiral galaxies.Galáxias S0 são supostamente uma fase de transição na vida de uma galáxia, na qual partilha propriedades tanto de galáxias elípticas como de galáxias espirais. Assim, a compreensão deste tipo de objeto pode trazer informações importantes sobre todo o campo de evolução de galáxias. As galáxias lenticulares representam quase metade da população de galáxias gigantes no universo próximo, no entanto, a sua história de formação, e se são uma classe de objetos única ou composta, continuam a ser questões em aberto na astronomia moderna. Neste trabalho, estudamos esta classe de galáxias em três frentes usando diferentes conjuntos de dados: primeiro, olhamos para uma galáxia lenticular totalmente formada, NGC 3115, usando dados em variados comprimentos de onda em busca de recuperar a sua história de formação e evolução; em segundo lugar, olhamos para um evento que poderia gerar uma galáxia S0, a fusão massiva NGC 1487, usando dados em espectroscopia de campo integrado (IFS) do MUSE/VLT. Finalmente, estudamos a distribuição de galáxias S0 no universo local usando dados fotométricos do mapeamento S-PLUS. Reunindo estes três trabalhos, pretendemos proporcionar uma melhor compreensão das galáxias lenticulares no universo local e identificar quais são os progenitores e os cenários de formação mais prováveis em diferentes ambientes. No esquema de classificação de Hubble, galáxias lenticulares são definidas como tendo um disco, sem braços espirais. No entanto, um estudo mais detalhado revela que estas apresentam várias subcomponentes, como um disco, um bojo, e em alguns casos também uma barra e lentes. A decomposição de uma galáxia nas suas componentes permite recuperar os gradientes de cor presentes no sistema, a sua história de formação estelar e, finalmente, a sua história de formação. Utilizamos GALFITM para realizar esta decomposição em variados comprimentos de onda simultaneamente da galáxia lenticular mais próxima da Via Láctea, NGC 3115, resultando na descrição de suas populações estelares em três componentes principais, incluindo um bojo, um disco fino e um disco espesso. Recuperamos diagramas cor-magnitude pixelizados e a distribuição espectral de energia das componentes. Os resultados mostram que a maioria da massa da galáxia se encontra na região do bojo e que esta é a componente mais azul, sugerindo tanto atividade de núcleos ativos de galáxias (AGN) como eventos recentes de formação estelar. Mostramos que esta galáxia possui uma barra e características semelhantes à espirais, provavelmente criadas durante uma interação recente. Finalmente, propomos um cenário para a formação de NGC 3115 com base numa fusão inicial rica em gás, seguida por uma sequência de acréscimos e feedback de AGN, responsável pela cessão da formação estelar na galáxia, até que um encontro recente reacendeu a formação estelar no bojo e gerou as características em espiral observadas. É bem conhecido que galáxias S0 podem ser formadas por diferentes processos, e por isso aqui estudamos a eficácia de fusões massivas como um dos mecanismos de formação das galáxias S0. Usando dados em IFS do MUSE/VLT da galáxia em interação NGC 1487, estudamos as propriedades físicas e cinemáticas do sistema. Encontramos uma inversão no gradiente de metalicidade do sistema NGC 1487, explicada por processos de mistura de metais. O campo de velocidade revelou um padrão de rotação numa das subcomponentes de NGC 1487, mostrando que a galáxia pode estar em processo de recriação de um disco. Concluímos que se a evolução do sistema levar à formação de um disco, então este evento de fusão poderia evoluir passivamente para se tornar uma galáxia S0 em vários giga-anos. Finalmente, para compreender a distribuição das galáxias lenticulares no universo local, e o papel dos ambientes na sua formação, determinamos redshifts fotométricos e tipos espectrais de galáxias no mapeamento S-PLUS. Identificamos os objetos melhor ajustados pelo espectro teórico de galáxias lenticulares e encontramos a sua distribuição em todo o universo local. Os resultados mostram que as S0s se encontram, na sua maioria, em regiões aglomeradas e estão dificilmente isoladas. Além disso, mostramos que entre as galáxias identificadas como lenticulares de acordo com o seu tipo espectral, as que apresentam baixas taxas de formação estelar também apresentam uma morfologia visual típica das galáxias lenticulares, enquanto as que apresentam altas taxas de formação estelar são provavelmente lenticulares com atividade nuclear ou galáxias espirais classificadas incorretamente

Paraneoplastic cerebellar ataxia associated with anti-Hu antibodies and benign ganglioneuroma

We describe a case of cerebellar ataxia associated with anti-Hu antibodies and benign ganglioneuroma. A 28-year-old woman developed progressive ataxia with hyporeflexia at the age of 19. Brain MRI showed progressive cerebellar atrophy. Neurophysiological studies, screening of immune-mediated ataxias, oncological markers, vitamin E and genetic tests for spinocerebellar ataxia types 1,2,3, Friedreich ataxia and POLG1 were negative. Anti-Hu antibodies were positive in Western blot and indirect immunofluorescence (1:640). Total-body computed tomography revealed a mediastinum mass; the histological diagnosis was maturing ganglioneuroma. Immunohisto - chemistry showed a mild reaction between the tumor and the patient’s serum, and no reaction between the tumor and control serum. After surgery, serum anti-Hu titer decreased, while ataxic symptoms initially worsened and then stabilized. Ganglioneuroma is a benign tumor, usually derived from the maturation of a neuroblastoma. The benign histology and the presence of anti-Hu antibodies could be related to the positive oncological prognosis and to the slow clinical course mimicking a degenerative ataxia

Constraining the stellar populations of ultra-diffuse galaxies in the MATLAS survey using spectral energy distribution fitting

International audienceWe use spectral energy distribution fitting to place constraints on the stellar populations of 59 ultra-diffuse galaxies (UDGs) in the low-to-moderate density fields of the MATLAS survey. We use the routine PROSPECTOR, coupled with archival data in the optical from the Dark Energy Camera Legacy Survey, and near- and mid-infrared imaging from the Wide-field Infrared Survey Explorer, to recover the stellar masses, ages, metallicities, and star formation time-scales of the UDGs. We find that a subsample of the UDGs lies within the scatter of the mass-metallicity relation (MZR) for local classical dwarfs. However, another subsample is more metal-poor, being consistent with the evolving MZR at high redshift. We investigate UDG positioning trends in the mass-metallicity plane as a function of surface brightness, effective radius, axis ratio, local volume density, mass-weighted age, star formation time-scale, globular cluster (GC) counts, and GC specific frequency. We find that our sample of UDGs can be separated into two main classes: Class A: comprised of UDGs with lower stellar masses, prolonged star formation histories (SFHs), more elongated, inhabiting less dense environments, hosting fewer GCs, younger, consistent with the classical dwarf MZR, and fainter. Class B: UDGs with higher stellar masses, rapid SFHs, rounder, inhabiting the densest of our probed environments, hosting on average the most numerous GC systems, older, consistent with the high-redshift MZR (i.e. consistent with early-quenching), and brighter. The combination of these properties suggests that UDGs of Class A are consistent with a 'puffed-up dwarf' formation scenario, while UDGs of Class B seem to be better explained by 'failed galaxy' scenarios