Article
Astronomy & Astrophysics
Klaudia Kowalczyk, Ewa L. Lokas
Summary: Dwarf spheroidal galaxies, which are strongly dominated by dark matter, are perfect for studying dark matter distribution and testing theories of structure formation. By using the Schwarzschild orbit superposition method, researchers were able to model these galaxies and obtain tighter confidence regions on density and velocity anisotropy profiles. The study also found that the anisotropy parameters slightly increase with radius and are significantly different for each stellar population.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
J. Roman, P. M. Sanchez-Alarcon, J. H. Knapen, R. Peletier
Summary: We analysed the dwarf galaxy UGC 7346 and found evidence suggesting the formation of a nuclear star cluster (NSC) in its earlier stages. Remnants of a past interaction and concentrated globular cluster (GC) candidates towards the centre of the galaxy support this. The central concentration of GCs is likely produced by the dynamical friction of merger, making UGC 7346 a unique case of NSC formation. These findings provide a natural explanation for the environmental correlations found for the nucleation fraction in early-type dwarf galaxies.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Ciria Lima-Dias, Antonela Monachesi, Sergio Torres-Flores, Arianna Cortesi, Daniel Hernandez-Lang, Carlos Eduardo Barbosa, Claudia Mendes de Oliveira, Daniela Olave-Rojas, Diego Pallero, Laura Sampedro, Alberto Molino, Fabio R. Herpich, Yara L. Jaffe, Ricardo Amorin, Ana L. Chies-Santos, Paola Dimauro, Eduardo Telles, Paulo A. A. Lopes, Alvaro Alvarez-Candal, Fabricio Ferrari, Antonio Kanaan, Tiago Ribeiro, William Schoenell
Summary: The study of Hydra cluster galaxies shows that about 88% of the galaxies are quenched, with possible substructures within the cluster. The Sersic index of galaxies varies with wavelength and galaxy type, but remains constant with respect to clustercentric distance and density.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Yasuhiro Hashimoto, Hans Boehringer, Keiichi Umetsu
Summary: In this study, we investigate the luminosity function of dwarf galaxies in 33 clusters at redshifts ranging from 0.15 to 0.3. We find that the faint end of the cluster luminosity function has a relatively flat slope, comparable to the field luminosity function. Additionally, the faint-end slope becomes steeper at larger cluster-centric distances and for blue dwarf galaxies. The X-ray luminosity of the clusters also affects the slope, although there are significant variations among individual clusters.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
A. E. Watkins, H. Salo, S. Kaviraj, C. A. Collins, J. H. Knapen, A. Venhola, J. Roman
Summary: Dwarf galaxies are important cosmological tools, but key parameters such as the relationship between size and mass are still debated. This study re-examines the dwarf population in the Fornax Cluster and finds a population of structural outliers with lower central mass surface density and larger half-light radii, likely formed through tidal disturbances. Comparing these outliers with ultra-diffuse galaxies (UDGs), it is found that the UDG classification lacks discriminatory power.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Emmanuel Rios-Lopez, Christopher Anorve, Hector J. Ibarra-Medel, Omar Lopez-Cruz, Joaquin Alvira-Enriquez, Gabriela Iacobuta, Mabel Valerdi
Summary: This study conducted a detailed analysis of 101 bright 2MASS galaxies, revealing discrepancies in photometric and structural parameters between early-type and late-type galaxies. By combining structural parameters with scaling relations and kinematic data, the study successfully separated classical bulges from pseudo-bulges, with around 40% of the sample galaxies classified as pseudo-bulges, predominantly found in late-type galaxies. The findings also confirmed trends in the distributions of certain physical parameters, such as Sersic index and B/T and q ratios, in agreement with previous one-dimensional studies.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Jessica M. Hislop, Thorsten Naab, Ulrich P. Steinwandel, Natalia Lahen, Dimitrios Irodotou, Peter H. Johansson, Stefanie Walch
Summary: This article discusses the properties of star clusters in isolated dwarf galaxies based on a series of simulations. The results show that varying the star formation efficiency does not affect the formation and outflow rates of stars. Lower efficiencies result in the formation of larger and more tightly bound star clusters, while higher efficiencies lead to shallower cluster mass functions and a decrease in cluster formation efficiency. However, none of the simulations can produce low mass clusters that match the observed structural properties.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Anna de Graaff, James Trayford, Marijn Franx, Matthieu Schaller, Joop Schaye, Arjen van der Wel
Summary: In this study, we investigate the differences between the sizes and morphologies inferred from the stellar mass distributions and the optical light distributions of galaxies. Our results show that the sizes derived from the optical light distributions are systematically larger than those derived from the stellar mass distributions. However, using the r-band sizes significantly improves the agreement between the simulated and observed stellar mass-size relation. Furthermore, we find that the morphologies of the simulated galaxies are closer to exponential discs rather than bulge-like structures.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Teymoor Saifollahi, Ignacio Trujillo, Michael A. Beasley, Reynier F. Peletier, Johan H. Knapen
Summary: Studies have found that previous estimates of the number of globular clusters around DF44 in the Coma cluster were higher, while new research indicates a lower actual number, consistent with other dwarf galaxies of similar stellar mass, and the dark matter halo mass also matches expectations.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
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
Katja Fahrion, Teodora-Elena Bulichi, Michael Hilker, Ryan Leaman, Mariya Lyubenova, Oliver Muller, Nadine Neumayer, Francesca Pinna, Marina Rejkuba, Glenn van de Ven
Summary: Nuclear star clusters (NSCs) formation depends on the mass of the galaxies. Low-mass NSCs predominantly form from the merger of globular clusters (GCs) in dwarf galaxies, while high-mass NSCs in massive galaxies assemble through central enriched star formation. Spectral analysis of nine nucleated late-type dwarf galaxies shows that NSCs in low-mass galaxies mainly grow through the inspiral of GCs, while central star formation can contribute to NSC growth in more massive galaxies.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Nelvy Choque-Challapa, J. Alfonso L. Aguerri, Pavel E. Mancera Pina, Reynier Peletier, Aku Venhola, Marc Verheijen
Summary: In this study, 12 galaxy clusters were analyzed to identify dwarf galaxy candidates, revealing that the distribution of dwarfs is influenced by the cluster environment and tends to increase with distance from the cluster center. These results highlight the impact of the cluster environment on the observational properties of low-mass haloes.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
D. O. Cook, J. C. Lee, A. Adamo, D. Calzetti, R. Chandar, B. C. Whitmore, A. Aloisi, M. Cignoni, D. A. Dale, B. G. Elmegreen, M. Fumagalli, K. Grasha, K. E. Johnson, R. C. Kennicutt, H. Kim, S. T. Linden, M. Messa, G. Ostlin, J. E. Ryon, E. Sacchi, D. A. Thilker, M. Tosi, A. Wofford
Summary: We studied the relationship between the properties of young star clusters and their host galaxies in 23 dwarf and irregular galaxies observed by the Hubble Space Telescope (HST) Legacy ExtraGalactic Ultraviolet Survey (LEGUS). We found that there were no significant correlations between the properties of the star clusters and the star formation rate (SFR) density of the host galaxies.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
M. Siudek, M. Mezcua, J. Krywult
Summary: Dwarf galaxies hosting active galactic nuclei (AGNs) are studied to understand their relationship with the environment. Previous studies have focused on low-redshift (z < 0.5) dwarf galaxies. In this study, the environments of dwarf galaxies at 0.5 < z < 0.9 are investigated using the VIPERS survey. It is found that AGN and non-AGN dwarf galaxies prefer low-density environments, and the presence of AGNs does not affect the properties of the host galaxies.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Seyda Sen, Ersin Gogus, Reynier F. Peletier, Nelvy Choque-Challapa, Amirnezam Amiri
Summary: In this study, a deep search and analysis of X-ray sources in dwarf galaxies within twelve galaxy clusters is conducted. The researchers found 20 X-ray emitting dwarf galaxies, indicating their likelihood of being black holes. The study also estimated the mass range of these black holes using a scaling relation and observed a trend between X-ray to optical flux ratio and X-ray flux, emphasizing the importance of X-ray observations in studying dwarf galaxy properties.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Rachana Bhatawdekar, Christopher J. Conselice
Summary: New measurements of UV spectral slope beta for galaxies at z=6-9 in the Frontier Field cluster MACS J0416.1-2403 and its parallel field show a strong correlation between beta and stellar mass at all redshifts, while no significant correlation with redshift M-1500 was found. Additionally, there is a correlation between beta and star formation rate, indicating a relationship between beta values and processes driving overall star formation rate and stellar mass assembly.
ASTROPHYSICAL JOURNAL
(2021)
Article
Astronomy & Astrophysics
T. K. Garratt, K. E. K. Coppin, J. E. Geach, O. Almaini, W. G. Hartley, D. T. Maltby, C. J. Simpson, A. Wilkinson, C. J. Conselice, M. Franco, R. J. Ivison, M. P. Koprowski, C. C. Lovell, A. Pope, D. Scott, P. van der Werf
Summary: In this study, new empirical constraints on the evolution of rho(H2), the cosmological mass density of molecular hydrogen, back to z approximate to 2.5 are presented. The research employs a statistical approach measuring the average observed 850 mu m flux density of near-infrared selected galaxies as a function of redshift, resulting in significantly reduced statistical uncertainties on rho(H2) at z approximate to 2.5. The findings suggest that the epoch of molecular gas coincides with the peak epoch of star formation driven by a larger supply of molecular gas in galaxies rather than a significant evolution of the star formation rate (SFR) efficiency within individual galaxies at z approximate to 2.
ASTROPHYSICAL JOURNAL
(2021)
Article
Astronomy & Astrophysics
C. Tohill, L. Ferreira, C. J. Conselice, S. P. Bamford, F. Ferrari
Summary: The study extends the use of CNNs to measure non-parametric galaxy structural quantities, showing high stability and better performance under low signal-to-noise conditions, and significantly faster speed compared to traditional methods. Despite systemic biases with redshift, the method is able to accurately reproduce non-parametric galaxy morphologies, demonstrating the potential of neural networks to provide superior results in substantially less time.
ASTROPHYSICAL JOURNAL
(2021)
Article
Astronomy & Astrophysics
Mikkel Theiss Kristensen, Kevin A. Pimbblet, Brad K. Gibson, Samantha J. Penny, Sophie Koudmani
Summary: Through cosmological simulations, it is found that the activity of active galactic nuclei (AGN) in dwarf galaxies is significantly influenced by their merger histories and environments, indicating that mergers and environments play an important role in AGN activity.
ASTROPHYSICAL JOURNAL
(2021)
Article
Astronomy & Astrophysics
Leonardo Ferreira, Christopher J. Conselice, Ulrike Kuchner, Clar-Brid Tohill
Summary: In this study, a machine-learning framework based on a convolutional neural network is developed to distinguish between star-forming galaxies and post-mergers. The framework successfully separates these galaxies with higher accuracy compared to previous methods, and the new measurements provide insights into the formation and evolution of galaxies.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Leonardo Ferreira, Nathan Adams, Christopher J. Conselice, Elizaveta Sazonova, Duncan Austin, Joseph Caruana, Fabricio Ferrari, Aprajita Verma, James Trussler, Tom Broadhurst, Jose Diego, Brenda L. Frye, Massimo Pascale, Stephen M. Wilkins, Rogier A. Windhorst, Adi Zitrin
Summary: This study presents early results on the morphological and structural properties of galaxies at z > 3 observed with the JWST. The discovery of a higher number of disk galaxies at z > 1.5 compared to the Hubble Space Telescope observations is surprising.
ASTROPHYSICAL JOURNAL LETTERS
(2022)
Article
Astronomy & Astrophysics
Massimo Pascale, Brenda L. Frye, Jose Diego, Lukas J. Furtak, Adi Zitrin, Tom Broadhurst, Christopher J. Conselice, Liang Dai, Leonardo Ferreira, Nathan J. Adams, Patrick Kamieneski, Nicholas Foo, Patrick Kelly, Wenlei Chen, Jeremy Lim, Ashish K. Meena, Stephen M. Wilkins, Rachana Bhatawdekar, Rogier A. Windhorst
Summary: The first deep field images from the James Webb Space Telescope (JWST) reveal new lensed images at uncharted infrared wavelengths, with unprecedented depth and resolution. These images provide opportunities for detailed research on the redshift, chemical abundances, and gas dynamics of distant galaxies. The study also found an Einstein cross candidate and evidence of past dynamical disturbances.
ASTROPHYSICAL JOURNAL LETTERS
(2022)
Article
Astronomy & Astrophysics
Rogier A. Windhorst, Seth H. Cohen, Rolf A. Jansen, Jake Summers, Scott Tompkins, Christopher J. Conselice, Simon P. Driver, Haojing Yan, Dan Coe, Brenda Frye, Norman Grogin, Anton Koekemoer, Madeline A. Marshall, Rosalia O'Brien, Nor Pirzkal, Aaron Robotham, Russell E. Ryan, Christopher N. A. Willmer, Timothy Carleton, Jose M. Diego, William C. Keel, Paolo Porto, Caleb Redshaw, Sydney Scheller, Stephen M. Wilkins, S. P. Willner, Adi Zitrin, Nathan J. Adams, Duncan Austin, Richard G. Arendt, John F. Beacom, Rachana A. Bhatawdekar, Larry D. Bradley, Tom Broadhurst, Cheng Cheng, Francesca Civano, Liang Dai, Herve Dole, Jordan C. J. D'Silva, Kenneth J. Duncan, Giovanni G. Fazio, Giovanni Ferrami, Leonardo Ferreira, Steven L. Finkelstein, Lukas J. Furtak, Hansung B. Gim, Alex Griffiths, Heidi B. Hammel, Kevin C. Harrington, Nimish P. Hathi, Benne W. Holwerda, Rachel Honor, Jia-Sheng Huang, Minhee Hyun, Myungshin Im, Bhavin A. Joshi, Patrick S. Kamieneski, Patrick Kelly, Rebecca L. Larson, Juno Li, Jeremy Lim, Zhiyuan Ma, Peter Maksym, Giorgio Manzoni, Ashish Kumar Meena, Stefanie N. Milam, Mario Nonino, Massimo Pascale, Andreea Petric, Justin D. R. Pierel, Maria del Carmen Polletta, Huub J. A. Roettgering, Michael J. Rutkowski, Ian Smail, Amber N. Straughn, Louis-Gregory Strolger, Andi Swirbul, James A. A. Trussler, Lifan Wang, Brian Welch, J. Stuart B. Wyithe, Min Yun, Erik Zackrisson, Jiashuo Zhang, Xiurui Zhao
Summary: This paper provides an overview and details the rationale, methods, and initial findings of the PEARLS project, which utilizes NIRCam images to survey extragalactic areas. The project aims to study galaxy assembly, AGN growth, and First Light, and is expected to contribute significant insights to the field of astronomy.
ASTRONOMICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Ekta A. Shah, Jeyhan S. Kartaltepe, Christina T. Magagnoli, Isabella G. Cox, Caleb T. Wetherell, Brittany N. Vanderhoof, Kevin C. Cooke, Antonello Calabro, Nima Chartab, Christopher J. Conselice, Darren J. Croton, Alexander de la Vega, Nimish P. Hathi, Olivier Ilbert, Hanae Inami, Dale D. Kocevski, Anton M. Koekemoer, Brian C. Lemaux, Lori Lubin, Kameswara Bharadwaj Mantha, Stefano Marchesi, Marie Martig, Jorge Moreno, Belen Alcalde Pampliega, David R. Patton, Mara Salvato, Ezequiel Treister
Summary: Observations and simulations of interacting galaxies and mergers have shown that interactions can significantly enhance star formation rates and fueling of active galactic nuclei. However, at higher redshift, the level of star formation enhancement induced by interactions is lower.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Alex Griffiths, Christopher J. Conselice, Leonardo Ferreira, Daniel Ceverino, Pablo G. Perez-Gonzalez, Olga Vega, Daniel Rosa-Gonzalez, Anton M. Koekemoer, Danilo Marchesini, Jose Miguel Rodriguez Espinosa, Lucia Rodriguez-Munoz, Belen Alcalde Pampliega, Elena Terlevich
Summary: We conducted a study on the escape fractions of UV photons from a sample of lensed low-mass emission line-selected galaxies. Our findings suggest that these low-mass galaxies may not be significant sources of reionization, based on the relatively low Lyman-continuum escape fraction limits.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Christopher J. Conselice, Carl J. Mundy, Leonardo Ferreira, Kenneth Duncan
Summary: In this study, we measure the impact of major and minor mergers on the formation of stellar masses in galaxies over the redshift range 0 < z < 3. By analyzing a combination of the latest ground-based near-infrared imaging data, we find that major mergers contribute more to the growth of stellar mass in galaxies compared to minor mergers during this epoch. Overall, merging events will more than double the mass of massive galaxies over this period.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Timothy Carleton, Seth H. Cohen, Brenda L. Frye, Alex Pigarelli, Jiashuo Zhang, Rogier A. Windhorst, Jose M. Diego, Christopher J. Conselice, Cheng Cheng, Simon P. Driver, Nicholas Foo, Rachana A. Bhatawdekar, Patrick Kamieneski, Rolf A. Jansen, Haojing Yan, Jake Summers, Aaron S. G. Robotham, Christopher N. A. Willmer, Anton M. Koekemoer, Scott Tompkins, Dan Coe, Norman A. Grogin, Madeline A. Marshall, Mario Nonino, Nor Pirzkal, Russell E. Ryan Jr
Summary: Despite the large number of locally identified ultradiffuse galaxies (UDGs), we still lack a full understanding of how they fit into the conventional theory of galaxy formation. Analyzing low surface brightness galaxies at high redshift has been challenging due to systematic effects and cosmological surface brightness dimming. In this study, we used deep near-IR observations from JWST to identify low stellar surface density galaxies (LDGs) at moderate redshift, which are likely the progenitors of local UDGs. Our analysis reveals significant differences between these LDGs and locally observed UDGs, indicating that the UDG progenitors at high z are bluer and more extended. We also find a slight overabundance of LDGs in the El Gordo cluster, and no deficit of LDGs in the center, suggesting that tidal destruction of LDGs is significant between z = 0.87 and z = 0.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Leonardo Ferreira, Christopher J. Conselice, Elizaveta Sazonova, Fabricio Ferrari, Joseph Caruana, Clar-Brid Tohill, Geferson Lucatelli, Nathan Adams, Dimitrios Irodotou, Madeline A. Marshall, Will J. Roper, Christopher C. Lovell, Aprajita Verma, Duncan Austin, James Trussler, Stephen M. Wilkins
Summary: This study presents the morphological and structural evolution of 3956 galaxies observed with JWST at 1.5 < z < 6.5. The results show that disk galaxies dominate in the mass range M-* > 10(9)M⊙ up to z = 6, contrary to previous beliefs.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Duncan Austin, Nathan Adams, Christopher J. Conselice, Thomas Harvey, Katherine Ormerod, James Trussler, Qiong Li, Leonardo Ferreira, Pratika Dayal, Ignas Juodzbalis
Summary: This study presents an early analysis of the search for high-redshift galaxies using deep JWST imaging in the NGDEEP field. The data reaches unprecedented depths, allowing for the identification of 16 new galaxies with redshifts greater than 8.5. Additionally, a series of faint, low-mass dwarf galaxies with blue colors and small sizes were discovered.
ASTROPHYSICAL JOURNAL LETTERS
(2023)
Article
Astronomy & Astrophysics
Mikkel Stockmann, Inger Jorgensen, Sune Toft, Christopher J. Conselice, Andreas Faisst, Berta Margalef-Bentabol, Anna Gallazzi, Stefano Zibetti, Gabriel B. Brammer, Carlos Gomez-Guijarro, Michaela Hirschmann, Claudia D. Lagos, Francesco M. Valentino, Johannes Zabl
Summary: The study reveals that very massive quiescent galaxies at z > 2 cannot passively evolve to the local Coma cluster relation alone, but must undergo significant structural evolution to mimic the sizes of local massive galaxies. The evolution of the FP and M/L scaling relations from z = 2 to present day is consistent with passive aging of the stellar population and minor merger structural evolution.
ASTROPHYSICAL JOURNAL
(2021)