Browsing by Author "Eigenthaler, Paul"
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- ItemA MUSE view of the core of the giant low-surface-brightness galaxy Malin 1(2024) Johnston, Evelyn J.; Galaz, Gaspar; Blana, Matias; Amram, Philippe; Boissier, Samuel; Eigenthaler, Paul; Epinat, Benoit; Junais; Ordenes-Briceno, Yasna; Puzia, Thomas; Weilbacher, Peter M.Aims. The central region of the giant low-surface-brightness galaxy Malin 1 has long been known to have a complex morphology, with evidence of a bulge, disc, and potentially a bar hosting asymmetric star formation. In this work, we use VLT/MUSE data to resolve the central region of Malin 1 in order to determine its structure. Methods. We used careful light profile fitting in every image slice of the datacube to create wavelength-dependent models of each morphological component, from which we were able to cleanly extract their spectra. We then used the kinematics and emission line properties from these spectra to better understand the nature of each component extracted from our model fitting. Results. We report the detection of a pair of distinct sources at the centre of this galaxy with a separation of similar to 1.05 '', which corresponds to a separation on sky of similar to 1.9 kpc. The radial velocity data of each object confirm that they both lie in the kinematic core of the galaxy. An analysis of the emission lines reveals that the central compact source is more consistent with being ionised through star formation and/or a LINER, while the off-centre compact source lies closer to the separation between star-forming galaxies and active galactic nuclei. Conclusions. This evidence suggests that the centre of Malin 1 hosts either a bar with asymmetric star formation or two distinct components. In the latter scenario, we propose two hypotheses for the nature of the off-centre compact source-it could either be a star-forming clump, containing one or more star clusters, that is in the process of falling into the core of the galaxy and eventually merging with the central nuclear star cluster, or it could be a clump of gas falling into the centre of the galaxy from either outside or from the disc and triggering star formation there.
- ItemExtending the evolution of the stellar mass-size relation at z ≤ 2 to low stellar mass galaxies from HFF and CANDELS(2021) Nedkova, Kalina, V; Haussler, Boris; Marchesini, Danilo; Dimauro, Paola; Brammer, Gabriel; Eigenthaler, Paul; Feinstein, Adina D.; Ferguson, Henry C.; Huertas-Company, Marc; Johnston, Evelyn J.; Kado-Fong, Erin; Kartaltepe, Jeyhan S.; Labbe, Ivo; Lange-Vagle, Daniel; Martis, Nicholas S.; McGrath, Elizabeth J.; Muzzin, Adam; Oesch, Pascal; Ordenes-Briceno, Yasna; Puzia, Thomas; Shipley, Heath, V; Simmons, Brooke D.; Skelton, Rosalind E.; Stefanon, Mauro; van der Wel, Arjen; Whitaker, Katherine E.We reliably extend the stellar mass-size relation over 0.2 <= z <= 2 to low stellar mass galaxies by combining the depth of Hubble Frontier Fields with the large volume covered by CANDELS. Galaxies are simultaneously modelled in multiple bands using the tools developed by the MegaMorph project, allowing robust size (i.e. half-light radius) estimates even for small, faint, and high redshift galaxies. We show that above 10(7) M-circle dot, star-forming galaxies are well represented by a single power law on the mass-size plane over our entire redshift range. Conversely, the stellar mass-size relation is steep for quiescent galaxies with stellar masses >= 10(10.3)M(circle dot) and flattens at lower masses, regardless of whether quiescence is selected based on star-formation activity, rest-frame colours, or structural characteristics. This flattening occurs at sizes of similar to 1 kpc at z <= 1. As a result, a double power law is preferred for the stellar mass-size relation of quiescent galaxies, at least above 10(7)M(circle dot). We find no strong redshift dependence in the slope of the relation of star-forming galaxies as well as of high mass quiescent galaxies. We also show that star-forming galaxies with stellar masses >= 10(9.5)M(circle dot) and quiescent galaxies with stellar masses >= 10(10.3)M(circle dot) have undergone significant size growth since z similar to 2, as expected; however, low mass galaxies have not. Finally, we supplement our data with predominantly quiescent dwarf galaxies from the core of the Fornax cluster, showing that the stellar mass-size relation is continuous below 10(7)M(circle dot), but a more complicated functional form is necessary to describe the relation.
- ItemIntrinsic 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, PaulWith 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.
- ItemRadial Velocity Survey for Planets around Young stars (RVSPY) : Target characterisation and high-cadence survey(EDP Sciences, 2022) Zakhozhay, Olga V.; Launhardt, Ralf; Müller, Andre; Eigenthaler, Paul; Hempel, Angela; Hempel, Maren; Henning, Thomas; Kim, Sam; Kurster, Martin; Lachaume, Régis; Manerikar, Yashodham; Pavlov, Alexey; Trifonov, Trifonov; Brems, Stefan S.; Reffert, Sabine; Gennaro, Mario; Kennedy G.M.; Patel, Jayshil A.Context. The occurrence rate and period distribution of (giant) planets around young stars is still not as well constrained as for older main-sequence stars. This is mostly due to the intrinsic activity-related complications and the avoidance of young stars in many large planet search programmes. Yet, dynamical restructuring processes in planetary systems may last significantly longer than the actual planet formation phase and may well extend long into the debris disc phase, such that the planet populations around young stars may differ from those observed around main-sequence stars. Aims. We introduce our Radial Velocity Survey for Planets around Young stars (RVSPY), which is closely related to the NaCo-ISPY direct imaging survey, characterise our target stars, and search for substellar companions at orbital separations smaller than a few au from the host star. Methods. We used the FEROS spectrograph, mounted to the MPG/ESO 2.2 m telescope in Chile, to obtain high signal-to-noise spectra and time series of precise radial velocities (RVs) of 111 stars, most of which are surrounded by debris discs. Our target stars have spectral types between early F and late K, a median age of 400 Myr, and a median distance of 45 pc. During the initial reconnaissance phase of our survey, we determined stellar parameters and used high-cadence observations to characterise the intrinsic stellar activity, searched for hot companions with orbital periods of up to 10 days, and derived the detection thresholds for longer-period companions. In our analysis we, have included archival spectroscopic data, spectral energy distribution, and data for photometric time series from the TESS mission. Results. For all target stars we determined their basic stellar parameters and present the results of the high-cadence RV survey and activity characterisation. We have achieved a median single-measurement RV precision of 6 m s−1 and derived the short-term intrinsic RV scatter of our targets (median 23 m s−1), which is mostly caused by stellar activity and decays with an age from >100 m s−1 at <20 Myr to <20 m s−1 at >500 Myr. We analysed time series periodograms of the high-cadence RV data and the shape of the individual cross-correlation functions. We discovered six previously unknown close companions with orbital periods between 10 and 100 days, three of which are low-mass stars, and three are in the brown dwarf mass regime. We detected no hot companion with an orbital period <10 days down to a median mass limit of ~1 MJup for stars younger than 500 Myr, which is still compatible with the established occurrence rate of such companions around main-sequence stars. We found significant RV periodicities between 1.3 and 4.5 days for 14 stars, which are, however, all caused by rotational modulation due to starspots. We also analysed the data for TESS photometric time series and found significant periodicities for most of the stars. For 11 stars, the photometric periods are also clearly detected in the RV data. We also derived stellar rotation periods ranging from 1 to 10 days for 91 stars, mostly from the TESS data. From the intrinsic activity-related short-term RV jitter, we derived the expected mass-detection thresholds for longer-period companions, and selected 84 targets for the longer-term RV monitoring
- ItemSpatially resolved stellar population parameters in the BCGs of two fossil groups(2014) Proctor, Robert N.; de Oliveira, Claudia Mendes; Eigenthaler, PaulWe report the results of Gemini/GMOS long-slit spectroscopic observations along the major and minor axes of the central galaxies in two fossil groups, SDSS J073422.21+265133.9 and SDSS J075828.11+374711.8 (the NGC 2484 group). Spatially resolved kinematics and stellar population parameters (ages, metallicities and alpha-element abundance ratios) derived using similar to 20 Lick indices are presented. Despite remarkable similarities in their morphologies, photometric properties (luminosity and colour) and kinematics, the two galaxies exhibit significantly different stellar population parameters. SDSS J073422.21+265133.9 exhibits a strong metallicity gradient (Delta [Z/H]Delta R similar to -0.4) all the way into the centre of the galaxy. It also exhibits an age profile that suggest a relatively recent, centrally concentrated burst of star formation superimposed on an older, more spatially extended population. NGC 2484, a well-known X-ray AGN, exhibits a flat core-like structure in its metallicity gradient, but no detectable age gradient. The a-element abundance ratio ([E/Fe]) profiles of the two galaxies are also significantly different. SDSS J073422.21+265133.9 exhibits a slightly positive gradient (Delta[E/H]Delta R similar to 0.1), perhaps again suggesting a more recent central burst of star formation, while NGC 2484 shows a negative gradient (Delta [E/H]/Delta R similar to -0.1), indicating that star formation may have happened 'inside out'. Our analysis of these two galaxies of similar mass, morphology and kinematics therefore suggests two different mechanisms to have been in action during their formation. Consequently, we conclude that the central galaxies of fossil groups cannot be considered a homogeneous group with regard to their formation processes or star formation histories.
- ItemStar formation properties of Hickson Compact Groups based on deep Ha imaging(2015) Eigenthaler, Paul; Ploeckinger, Sylvia; Verdugo, Miguel; Ziegler, Bodo
- ItemStellar population properties of ultracompact dwarfs in M87 : a mass-metallicity correlation connecting low-metallicity globular clusters and compact ellipticals(2018) Zhang, Hong Xin; Puzia, Thomas H.; Peng, Eric W.; Liu, Chengze; Coté, Patrick; Ferrarese, Laura; Duc, Pierre Alain; Eigenthaler, Paul; Lim, Sungsoon; Muñoz, Roberto P.
- ItemThe Next Generation Fornax Survey (NGFS). III. Revealing the Spatial Substructure of the Dwarf Galaxy Population Inside Half of Fornax's Virial Radius(2018) Órdenes Briceño, Yasna; Eigenthaler, Paul; Taylor, Matthew A.; Puzia, Thomas H.; Alamo-Martinez, Karla; Ribbeck, Karen X.; Munoz, Roberto P.; Zhang, Hongxin; Grebel, Eva K.; Ángel Ángel, Simón Andrés; Cote, Patrick; Ferrarese, Laura; Hilker, Michael; Lancon, Ariane; Mieske, Steffen; Miller, Bryan W.; Rong, Yu; Sanchez-Janssen, Ruben
- ItemThe Next Generation Fornax Survey (NGFS). IV. Mass and Age Bimodality of Nuclear Clusters in the Fornax Core Region(2018) Órdenes Briceño, Yasna; Puzia, Thomas H.; Eigenthaler, Paul; Taylor, Matthew A.; Munoz, Roberto P.; Zhang, Hongxin; Alamo-Martinez, Karla; Ribbeck, Karen X.; Grebel, Eva K.; Ángel Ángel, Simón Andrés; Cote, Patrick; Ferrarese, Laura; Hilker, Michael; Lancon, Ariane; Mieske, Steffen; Miller, Bryan W.; Rong, Yu; Sanchez-Janssen, Ruben
- ItemThe next generation fornax survey (NGFS). V. Discovery of a dwarf-dwarf galaxy pair at z=0.30 and its characterization using deep VLT/MUSE observations(2019) Johnston, E.J.; Eigenthaler, Paul; Puzia, Thomas H.; Órdenes Briceño, Yasna; Taylor, M.A.; Alamo Martinez, K.; Cote, P.; Galaz, Gaspar; Grebel, E.K.; Rong, Y.; Johnston, E.J.; Eigenthaler, Paul; Puzia, Thomas H.; Órdenes Briceño, Yasna; Taylor, M.A.; Alamo Martinez, K.; Cote, P.; Galaz, Gaspar; Grebel, E.K.; Rong, Y.
- ItemThe Next Generation Virgo Cluster Survey (NGVS). XXXII. A Search for Globular Cluster Substructures in the Virgo Galaxy Cluster Core(2018) Powalka, Mathieu; Puzia, Thomas H.; Lancon, Ariane; Longobardi, Alessia; Peng, Eric W.; Duc, Pierre-Alain; Alamo-Martinez, Karla; Blakeslee, John P.; Cote, Patrick; Cuillandre, Jean-Charles; Durrell, Patrick; Eigenthaler, Paul; Ferrarese, Laura; Guhathakurta, Puragra; Gwyn, S. D. J.; Hudelot, Patrick; Liu, Chengze; Mei, Simona; Munoz, Roberto P.; Roediger, Joel; Sanchez-Janssen, Ruben; Toloba, Elisa; Zhang, Hongxin
- ItemThe Survey of Centaurus A's Baryonic Structures (SCABS) – II. The extended globular cluster system of NGC 5128 and its nearby environment(2017) Taylor, Matthew A.; Puzia, Thomas H.; Muñoz, Roberto P.; Mieske, Steffen; Lançon, Ariane; Zhang, Hongxin; Eigenthaler, Paul; Bovill, Mia Sauda