Article
Astronomy & Astrophysics
Yingtian Chen, Oleg Y. Gnedin
Summary: The presence of globular clusters (GCs) in some satellite galaxies and their absence in most dwarf galaxies pose a challenge for understanding their origins. We investigated the stochasticity and number of GCs in dwarf galaxies and found that more than 50% of low-mass dwarf galaxies do not host GCs, while higher-mass dwarf galaxies almost always contain some GCs. Our findings are consistent with observations and confirm a linear relationship between GC system mass and halo mass. We also highlighted the potential bias in observational samples due to detection limits and large radii.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Charli M. Sakari, George Wallerstein
Summary: This paper presents [Fe/H] ratios for globular clusters in the outer halo of the Andromeda Galaxy based on moderate-resolution, integrated light spectroscopy. The results show that the outer halo globular clusters are generally more metal-poor than typical inner halo globular clusters, with some exceptions that may have been accreted from dwarf satellites. The metallicities of these clusters also provide important constraints on the nature of the substructure in the outer halo and the dwarf satellites responsible for it.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
H. J. Leath, M. A. Beasley, A. Vazdekis, N. Salvador-Rusinol, A. Gvozdenko
Summary: This study investigates the determination of stellar population parameters of extragalactic Globular Clusters through their integrated spectroscopy. Previous observations suggested a splitting phenomenon in the H beta(o) line-strength index of Galactic globular clusters, which was thought to be caused by the presence of Blue straggler stars. However, new findings reveal that this splitting only occurs at intermediate to high metallicities and is due to an increased helium abundance, rather than an increased fraction of Blue straggler stars.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Robin Herlan, Alessandra Mastrobuono-Battisti, Nadine Neumayer
Summary: Observations show that M54, the nuclear star cluster of the Sgr dSph galaxy, matches a decayed globular cluster (GC) in a dark matter (DM) halo with a density profile proportional to r(-gamma) and gamma <= 1, based on its rotational signal and flattening. Steeper density profiles result in highly rotating and more flattened nuclear star clusters (NSCs) that do not match the properties of M54.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Jiaming Pan, Eric F. Bell, Adam Smercina, Paul Price, Colin T. Slater, Jeremy Bailin, Roelof S. de Jong, Richard D'Souza, In Sung Jang, Antonela Monachesi
Summary: The study focuses on the outer halo globular cluster populations and their significance in understanding galaxy merging, GC accretion, and the origin of GCs. By utilizing Subaru Hyper Suprime-Cam (HSC) data, GALEX, IRAC, and Gaia EDR3 data, candidate GCs in the M81 group's outer halo were selected for confirmation and future research. The findings suggest that known GCs in the M81 group have slightly larger sizes than the Subaru PSF, and their colors in optical bands are only slightly different from stars. The inclusion of archival IRAC data greatly improves the separation of GCs from stars and compact background galaxies.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Rose A. Finn, Benedetta Vulcani, Gregory Rudnick, Michael L. Balogh, Vandana Desai, Pascale Jablonka, Dennis Zaritsky
Summary: We investigate the role of dense environments in suppressing star formation by studying galaxies with log(10)(M- * / M-?) > 9.7 in nine clusters from the Local Cluster Survey. We find that SFR suppression increases with increasing bulge-to-total ratio in all environments. In addition, cluster and infall galaxies have more suppressed SFRs compared to field counterparts at all values of B/T, suggesting an additional mechanism in dense environments.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Charli M. Sakari, Matthew D. Shetrone, Andrew McWilliam, George Wallerstein
Summary: G1 is a massive star cluster in M31 with moderately metal-poor abundance, alpha enhancement, and unique signatures of Na and Al enrichment, suggesting its origin in a fairly massive galaxy and intimate connection with globular cluster formation.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Shoucheng Wang, Bingqiu Chen, Jun Ma
Summary: Determining the metallicities and ages of M31 clusters is crucial for understanding the formation and evolution of the M31 galaxy. Utilizing LAMOST spectra and multi-band photometry data, a new algorithm was developed to estimate metallicities and ages of 346 M31 clusters. The study successfully derived parameters for 53 young and 293 old clusters, with results in good agreement with existing literature and also providing new age and metallicities data for a significant number of sources.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Sebastian Trujillo-Gomez, J. M. Diederik Kruijssen, Benjamin W. Keller, Marta Reina-Campos
Summary: The research reveals that the globular cluster (GC) population in the NGC 1052-DF2 galaxy not only has abnormal luminosity, but also formed in extreme environmental conditions, suggesting that the GC system of DF2 may have formed during a major merger, leading to the galaxy becoming an ultra-diffuse galaxy.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Maria Luisa Buzzo, Duncan A. Forbes, Jean P. Brodie, Steven R. Janssens, Warrick J. Couch, Aaron J. Romanowsky, Jonah S. Gannon
Summary: In this study, the large-scale structure (LSS) of globular clusters (GCs) in the NGC 1052 group was mapped using optical CFHT imaging data. Two GC density maps were recovered, revealing overdensities around the massive galaxies and NGC 1052 itself, coinciding with previously identified stellar streams and tidal features. However, no GCs connecting these structures to any of the dwarf galaxies were found. Two other dwarf galaxies in the group were also found to host GC systems. The study concludes that the GC distribution in the group does not strongly support any specific formation scenario but favors scenarios involving galaxy-galaxy interactions and coeval formation of GCs around dwarf galaxies without dark matter.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Cristina Martinez-Lombilla, Sarah Brough, Mireia Montes, Roberto Baena-Galle, Mohammad Akhlaghi, Raul Infante-Sainz, Simon P. Driver, Benne W. Holwerda, Kevin A. Pimbblet, Aaron S. G. Robotham
Summary: We conducted a pilot study using Hyper Suprime-Cam Public Data Release 2 (HSC-PDR2) images to analyze extended faint structures in groups of galaxies. By analyzing the intragroup light (IGL) in group 400138 from the GAMA survey, we measured the most extended IGL to date reaching a semimajor axis of 275 kpc. The IGL showed younger stellar populations and lower metal richness compared to the host group galaxies, suggesting tidal stripping as the main driver of IGL buildup.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Shoucheng Wang, Jun Ma
Summary: By conducting deep observations of the brightest globular cluster (GC1) in M 81, researchers have determined its age to be 13.0 +/- 2.90 billion years and mass to be 1.06-1.48x10^7 solar masses. The R-h vs M-V diagram suggests that GC1 is more likely an accreted former nuclear star cluster rather than a classical globular cluster like the majority found in the Milky Way.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Seunghwan Lim, Douglas Scott, Arif Babul, David J. Barnes, Scott T. Kay, Ian G. McCarthy, Douglas Rennehan, Mark Vogelsberger
Summary: This study shows that current galaxy formation models do not predict enough star formation in protoclusters to match observations, with predicted star formation rates significantly lower than those seen in reality. By analyzing a well-studied protocluster core, it is found that star formation efficiency of protocluster galaxies is higher than predicted. The impact of numerical resolution on the simulations is significant, with a decrease in spatial resolution leading to a drop in star formation rates.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Xi Meng, Oleg Y. Gnedin
Summary: We investigated the evolution of tidal fields experienced by massive star clusters in Milky Way-sized galaxies using cosmological simulations. We found that the tidal force on clusters is strongest in the first few hundred million years after formation, after which it plateaus at a lower value. The fraction of time spent by clusters in high tidal strength regions decreases with age. In situ and ex situ clusters experience similar tidal fields at early ages, but in situ clusters generally experience stronger tidal fields at older ages due to their lower orbits. This difference in tidal fields affects the survival of clusters, with ex situ clusters typically having a higher bound fraction than in situ clusters.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
K. Fahrion, M. Lyubenova, G. van de Ven, M. Hilker, R. Leaman, J. Falcon-Barroso, A. Bittner, L. Coccato, E. M. Corsini, D. A. Gadotti, E. Iodice, R. M. McDermid, I. Martin-Navarro, F. Pinna, A. Poci, M. Sarzi, P. T. de Zeeuw, L. Zhu
Summary: Nuclear star clusters (NSCs) are the densest stellar systems in the Universe and are thought to form via mergers of star clusters or in situ star formation at galaxy centers. Research shows that NSCs in low-mass galaxies are more metal-poor than their hosts, while NSCs in massive galaxies exhibit diverse star formation histories. There is a clear transition in the dominant formation channel of NSCs with both galaxy and NSC mass.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Sophia Lilleengen, Michael S. Petersen, Denis Erkal, Jorge Penarrubia, Sergey E. Koposov, Ting S. Li, Lara R. Cullinane, Alexander P. Ji, Kyler Kuehn, Geraint F. Lewis, Dougal Mackey, Andrew B. Pace, Nora Shipp, Daniel B. Zucker, Joss Bland-Hawthorn, Tariq Hilmi
Summary: Recent research shows that the Large Magellanic Cloud (LMC) significantly impacts the Milky Way's stellar halo and stellar streams. This study examines how deformations of the Milky Way and LMC's dark matter haloes affect stellar streams and investigates if these effects can be observed. The Orphan-Chenab (OC) stream, which passes close to the LMC and spans a large portion of the Milky Way's halo, is the main focus. Using a basis function expansion, the Milky Way-LMC system is represented to capture their evolution in an N-body simulation. The study finds that the simulated OC stream is strongly influenced by the deformations of both the Milky Way and LMC, and these effects are larger than current observational errors. The Milky Way dipole has the greatest impact on the stream, followed by the evolution of the LMC's monopole and quadrupole. Detecting these effects would confirm a key prediction of collisionless, cold dark matter and serve as a powerful test for alternative dark matter and alternative gravity models.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
C. Meldorf, A. Palmese, D. Brout, R. Chen, D. Scolnic, L. Kelsey, L. Galbany, W. G. Hartley, T. M. Davis, A. Drlica-Wagner, M. Vincenzi, J. Annis, M. Dixon, O. Graur, C. Lidman, A. Moller, P. Nugent, B. Rose, M. Smith, S. Allam, D. L. Tucker, J. Asorey, J. Calcino, D. Carollo, K. Glazebrook, G. F. Lewis, G. Taylor, B. E. Tucker, A. G. Kim, H. T. Diehl, M. Aguena, F. Andrade-Oliveira, D. Bacon, E. Bertin, S. Bocquet, D. Brooks, D. L. Burke, J. Carretero, M. Carrasco Kind, F. J. Castander, M. Costanzi, L. N. da Costa, S. Desai, P. Doel, S. Everett, I Ferrero, D. Friedel, J. Frieman, J. Garcia-Bellido, M. Gatti, D. Gruen, J. Gschwend, G. Gutierrez, S. R. Hinton, D. L. Hollowood, K. Honscheid, D. J. James, K. Kuehn, M. March, J. L. Marshall, F. Menanteau, R. Miquel, R. Morgan, F. Paz-Chinchon, M. E. S. Pereira, A. A. Plazas Malagon, E. Sanchez, V Scarpine, I Sevilla-Noarbe, E. Suchyta, G. Tarle, T. N. Varga
Summary: Cosmological analyses with type Ia supernovae often overlook the varying dust properties in host galaxies, resulting in inaccurate conclusions. In this study, we use advanced modeling to characterize the dust parameters of 1100 Dark Energy Survey SN host galaxies and find that host dust has important impacts on SN cosmology, including a wide range of dust law slope R-V, lower R-V in high-stellar mass hosts compared to low-mass hosts, and a significant correlation between the Hubble diagram residuals of red SNe Ia and host R-V. These findings confirm recent predictions based on dust and provide insights into the "mass step" and intrinsic scatter in SN Ia analyses.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Zhen Wan, Anthony D. Arnold, William H. Oliver, Geraint F. Lewis, Holger Baumgardt, Mark Gieles, Vincent Henault-Brunet, Thomas de Boer, Eduardo Balbinot, Gary Da Costa, Dougal Mackey, Denis Erkal, Annette Ferguson, Pete Kuzma, Elena Pancino, Jorge Penarrubia, Nicoletta Sanna, Antonio Sollima, Roeland P. van der Marel, Laura L. Watkins
Summary: In this study, the outskirts of four globular clusters - 1261, NGC 4590, NGC 1904, and NGC 1851 - were surveyed using spectroscopic measurements from 2dF/AAOmega and FLAMES instruments. Chemo-dynamical information for individual stars were extracted to estimate the velocity dispersion profile and rotation of each cluster. The results show that NGC 1851 and NGC 1261 exhibit internal rotation, and the dispersion profiles of NGC 1261, NGC 1851, and NGC 1904 do not follow the predictions of limepy/spes models, while NGC 4590's results align with the predictions.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
S. Kamann, S. Saracino, N. Bastian, S. Gossage, C. Usher, D. Baade, I Cabrera-Ziri, S. E. de Mink, S. Ekstrom, C. Georgy, M. Hilker, S. S. Larsen, D. Mackey, F. Niederhofer, I Platais, D. Yong
Summary: Young star clusters are important for studying the effects of stellar rotation on stellar evolution. In a study of the star cluster NGC 1850, researchers measured the rotational velocities of stars and found a correlation between rotation and color. The findings impact our understanding of young massive clusters and provide new observational constraints for stellar evolutionary models.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
G. S. Da Costa, M. S. Bessell, Thomas Nordlander, Arvind C. N. Hughes, Sven Buder, A. D. Mackey, Lee R. Spitler, D. B. Zucker
Summary: The implementation of machine learning techniques in large-scale stellar spectroscopic surveys has successfully identified a sample of extremely metal-poor stars. Low-resolution spectroscopic follow-up revealed that the statistical selection approach was efficient and had low contamination, with a consistent metallicity distribution function. The positive outcomes of this study suggest that the same approach can be applied to future larger stellar spectroscopic surveys.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
McCullen Sandora, Vladimir Airapetian, Luke Barnes, Geraint F. Lewis, Ileana Perez-Rodriguez
Summary: Considering the rarity and sensitivity of life's origin, we may find ourselves in a universe that is well-equipped for creating the necessary conditions. Through investigating various origin of life scenarios, we discover a preference for weaker-gravity universes and a disfavoring of panspermia, solar radiation, and large impacts as disequilibrium sources. Furthermore, the multiverse makes several hypothesized habitability criteria compatible and highlights a contradiction between the emergence of life and intelligence being sensitive to disequilibrium production conditions.
Article
Astronomy & Astrophysics
McCullen Sandora, Vladimir Airapetian, Luke Barnes, Geraint F. Lewis
Summary: Stellar activity and planetary atmospheric properties can influence habitability, but they have not been adequately studied in the context of the multiverse. This study investigates the effects of solar wind, mass loss, and extreme ultra-violet flux on planetary atmospheres and their relationship with fundamental constants. It also explores the necessity of planetary magnetic fields for habitability and the impact of atmospheric effects on multiverse calculations.
Article
Astronomy & Astrophysics
McCullen Sandora, Vladimir Airapetian, Luke Barnes, Geraint F. F. Lewis
Summary: Recent discoveries of potentially habitable exoplanets around sunlike stars have prompted increased exploration of the physical conditions necessary for life. By considering the multiverse hypothesis, researchers can evaluate various habitability criteria and their compatibility with the existence of multiple universes, providing guidance for the search for extraterrestrial life and testing the multiverse hypothesis. This study examines different aspects of planetary habitability and demonstrates that the multiverse strongly influences these aspects, challenging previous assumptions about the necessity of a large moon for habitability and favoring certain mechanisms for water delivery to early Earth.
Article
Astronomy & Astrophysics
Nora Shipp, Nondh Panithanpaisal, Lina Necib, Robyn Sanderson, Denis Erkal, Ting S. Li, Isaiah B. Santistevan, Andrew Wetzel, Lara R. Cullinane, Alexander P. Ji, Sergey E. Koposov, Kyler Kuehn, Geraint F. Lewis, Andrew B. Pace, Daniel B. Zucker, Joss Bland-Hawthorn, Emily C. Cunningham, Stacy Y. Kim, Sophia Lilleengen, Jorge Moreno, Sanjib Sharma
Summary: This study presents the first detailed comparison between dwarf galaxy stellar streams in cosmological simulations and in the Milky Way. Streams around 13 Milky Way analogs in the FIRE-2 simulations are compared to streams observed by the Southern Stellar Stream Spectroscopic Survey (S5). The number and stellar mass distributions of detectable stellar streams are consistent, but there are differences in the distributions of pericenters and apocenters.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Charlie F. F. Sharpe, Luke A. A. Barnes, Geraint F. F. Lewis
Summary: We investigate the sensitivity of a universe's nuclear entropy after Big Bang nucleosynthesis (BBN) to variations in both the baryon-to-photon ratio and the temporal evolution of cosmological expansion. Specifically, we construct counterfactual cosmologies to quantify the degree by which these two parameters must vary from those in our Universe before we observe a substantial change in the degree of fusion, and thus nuclear entropy, during BBN. We find that, while the post-BBN nuclear entropy is indeed linked to baryogenesis and the Universe's expansion history, the requirement of leftover light elements does not place strong constraints on the properties of these two cosmological processes.
GENERAL RELATIVITY AND GRAVITATION
(2023)
Article
Astronomy & Astrophysics
Joseph F. Allingham, Mathilde Jauzac, David J. Lagattuta, Guillaume Mahler, Celine Boehm, Geraint F. Lewis, Dominique Eckert, Alastair Edge, Stefano Ettori
Summary: In this study, the strong lensing analysis of two galaxy clusters, MACS J0242.5-2132 and MACS J0949.8+1708, was conducted using observations from the Hubble Space Telescope and the Multi-Unit Spectroscopic Explorer instrument. The results show that MACS J0242 is a relatively relaxed cluster, while MACS J0949 exhibits a relaxing post-merger state.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Rok Vogrincic, Janez Kos, Tomaz Zwitter, Gregor Traven, Kevin L. Beeson, Klemen Cotar, Ulisse Munari, Sven Buder, Sarah L. Martell, Geraint F. Lewis, Gayandhi M. De Silva, Michael R. Hayden, Joss Bland-Hawthorn, Valentina D'Orazi
Summary: We used a large number of spectra from the GALAH survey to identify and analyze the diffuse interstellar bands (DIBs). By studying the absorption features of interstellar medium, we were able to determine the properties and potential carriers of the DIBs. Our findings contribute to a better understanding of the composition of interstellar medium as well as improving observational and modeling techniques related to dust and star formation. The excess equivalent width of certain DIBs compared to reddening suggests a more uniform distribution of DIB clouds compared to clumpy dust clouds.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Zhefu Yu, Paul Martini, A. Penton, T. M. Davis, C. S. Kochanek, G. F. Lewis, C. Lidman, U. Malik, R. Sharp, B. E. Tucker, M. Aguena, J. Annis, E. Bertin, S. Bocquet, D. Brooks, A. Carnero Rosell, D. Carollo, M. Carrasco Kind, J. Carretero, M. Costanzi, L. N. da Costa, M. E. S. Pereira, J. De Vicente, H. T. Diehl, P. Doel, S. Everett, I Ferrero, J. Garcia-Bellido, M. Gatti, D. W. Gerdes, D. Gruen, R. A. Gruendl, J. Gschwend, G. Gutierrez, S. R. Hinton, D. L. Hollowood, K. Honscheid, D. J. James, K. Kuehn, J. Mena-Fernandez, F. Menanteau, R. Miquel, B. Nichol, F. Paz-Chinchon, A. Pieres, A. A. Plazas Malagon, M. Raveri, A. K. Romer, E. Sanchez, V Scarpine, I Sevilla-Noarbe, M. Smith, E. Suchyta, M. E. C. Swanson, G. Tarle, M. Vincenzi, A. R. Walker, N. Weaverdyck
Summary: This study investigates the correlation between the broad line region radius and continuum luminosity (R-L relation) of active galactic nuclei (AGNs), which is critical for single-epoch mass estimates of supermassive black holes (SMBHs). The authors present 25 Mg II lags obtained from the Australian Dark Energy Survey RM project and develop quantitative criteria to select reliable lag measurements. The results significantly increase the number of Mg II lags and extend the R-L relation to higher redshifts and luminosities.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Amandine Doliva-Dolinsky, Nicolas F. Martin, Zhen Yuan, Alessandro Savino, Daniel R. Weisz, Annette M. N. Ferguson, Rodrigo A. Ibata, Stacy Y. Kim, Geraint F. Lewis, Alan W. McConnachie, Guillaume F. Thomas
Summary: We built a statistical framework to infer the global properties of the satellite system of the Andromeda galaxy (M31) using the properties of individual dwarf galaxies in a specific survey. This framework helped us determine the slope of the luminosity function, the spatial density distribution, and the size-luminosity relation of the dwarf galaxies. We found that there are still many faint or distant dwarf galaxies yet to be discovered around Andromeda.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Geraint F. Lewis, Brendon J. Brewer
Summary: A Bayesian-based analysis of 190 cosmologically distant quasars, photometrically observed over two decades, has revealed the long-expected presence of cosmic time dilation owing to the expansion of space imprinted on their variability.