Results 81 to 90 of about 346,903 (248)

Principal Component‐Based Classification of Blazar Candidates of Uncertain Type in the 4FGL/LAT

Astronomische Nachrichten, EarlyView.
ABSTRACT We adopted principal component analysis (PCA), linear discriminant analysis (LDA), and support vector machines (SVM), to study classification for a sample of 2708 Fermi blazars: 1142 BL Lac objects (BLLs), 759 flat spectrum radio quasars (FSRQs), and 807 blazar candidates of uncertain type (BCUs).
Wen‐Xin Yang, Guo‐Hai Chen, Jing‐Tian Zhu, Hong‐Guang Wang, Denis Bastieri, Xu‐Hong Ye, Jing‐Chao Liang, De‐Xiang Wu, Jiang‐He Yang, Anton A. Strigachev, Rumen S. Bachev, Jun‐Jie Feng, Yi Liu, Jun‐Hui Fan   +13 more
wiley   +1 more source

The Dual Origin of Stellar Halos [PDF]

, 2009
We investigate the formation of the stellar halos of four simulated disk galaxies using high-resolution, cosmological SPH + N-body simulations. These simulations include a self-consistent treatment of all the major physical processes involved in galaxy ...
Governato, Fabio, Willman, Beth, Zolotov, Adi, Brooks, Alyson M., Stinson, Greg, Quinn, Tom, Hogg, David W., Brook, Chris B.   +7 more
core   +1 more source

Stellar Halos of Nearby Edge-on Spiral Galaxies with the Dragonfly Telephoto Array

, 2022
Stellar halos are built up from stars stripped during past merger events, and therefore can inform us about a galaxy's accretion history. However, they are challenging to observe due to their faint and very extended nature. Most of the stellar halos
Gilhuly, Colleen Frances
core   +1 more source

Environmental Dependence of the Mass–Metallicity Relation in Cosmological Hydrodynamical Simulations

The Astrophysical Journal, 2023
We investigate the environmental dependence of the gas-phase metallicity for galaxies at z = 0 to z ≳ 2 and the underlying physical mechanisms driving this dependence using state-of-the-art cosmological hydrodynamical simulations.
Kai Wang, Xin Wang, Yangyao Chen
doaj   +1 more source

Direct SMBH Formation Driven by Runaway Stellar Collisions in Globally Unstable Stellar Systems

Astronomische Nachrichten, EarlyView.
ABSTRACT The fueling problem addresses the ultimate fate of the reservoirs of gas and stars driven into the deepest gravitational potential wells of galaxies, thus it may contain the Universe's densest concentrations of gas and stars. This raises a key question: does the infalling material collapse directly into a supermassive black hole, or can it ...
Marcelo C. Vergara, Andrés Escala
wiley   +1 more source

Early assembly of the most massive galaxies [PDF]

, 2009
The current consensus is that galaxies begin as small density fluctuations in the early Universe and grow by in situ star formation and hierarchical merging(1).
Chris A. Collins, Scott T Kay (16045382), Nicola Mehrtens (16047884), Ed Lloyd-Davies, Hoyle, Ben, Hosmer, Mark, Christopher J. Miller, Ben Hoyle, Mehrtens, Nicola, Robert G. Mann, Pedro T. P. Viana, Martin Sahlén (267044), S Adam Stanford (16061237), Mark Hosmer (16070585), Robert C Nichol (16067396), John P Stott (16070582), Martin Sahlén, Sahlen, Martin, John P. Stott, Kathy Romer (4460893), Matt Hilton (6956609), Viana, Pedro T. P., Mann, Robert G., Ben Hoyle (6914513), Stott, John P., Matt Hilton, Robert G Mann (7965452), Andrew Liddle, Stanford, S. Adam, Christopher J Miller (16070591), A. Kathy Romer, Davidson, Michael, Ed Lloyd-Davies (16075100), Romer, A. Kathy, Robert C. Nichol, Andrew Liddle (16042793), Pedro T P Viana (16045379), Nichol, Robert C., Kay, Scott T., Michael J. West, Chris A Collins (16061234), Scott T. Kay, Collins, Chris A., Michael Davidson, Mark Hosmer, West, Michael J., Michael Davidson (699678), S. Adam Stanford, Michael J West (5524436), Liddle, Andrew, Nicola Mehrtens, Miller, Christopher J., Hilton, Matt, Lloyd-Davies, Ed   +53 more
core   +1 more source

The connection between galaxy formation and the assembly of stellar halos in the Local Group

, 2015
I will review our current understanding of the assembly of stellar halos from a theoretical perspective. I will place particular emphasis on how observations of Local Group galaxies can be used to constrain the assembly history of both their stellar and ...
Helmi, Amina
core   +1 more source

Truncations in the X-Ray Halos of Early-type Galaxies as a Tracer of Feedback and Mergers

The Astrophysical Journal
The morphology of X-ray halos in early-type galaxies depends on key structure assembly processes, such as feedback and mergers. However, the signatures of these processes are difficult to characterize due to their faint and amorphous nature.
Nushkia Chamba, Pamela M. Marcum, Alejandro S. Borlaff, Pasquale Temi, Aneta Siemiginowska   +4 more
doaj   +1 more source

The Bochum Survey of the Southern Galactic Disk: IV. Multi‐Band Photometry

Astronomische Nachrichten, EarlyView.
ABSTRACT The Southern Galactic Disk Survey (GDS) monitored a mosaic of 268 fields along a 6°‐wide stripe in the southern galactic disk from September 2010 to September 2019. These fields were observed between 21 and 407 times sim r′$$ {r}^{\prime } $$ultaneously in (8mag≲r′≲18mag$$ 8\kern0.6em \mathrm{mag}\lesssim {r}^{\prime}\lesssim 18\kern0.6em ...
Julia Blex, Dominik J. Bomans, Kerstin Weis, Markus Demleitner, Moritz Hackstein, Anna Franckowiak, Michael Ramolla, Christian Westhues, Christofer Fein, Rolf Chini   +9 more
wiley   +1 more source

The Impact of Assembly Bias on the Galaxy Content of Dark Matter Halos [PDF]

, 2018
We study the dependence of the galaxy content of dark matter halos on large-scale environment and halo formation time using semi-analytic galaxy models applied to the Millennium simulation.
Sergio Contreras, Smith, Nicholas J., Norberg, Peder, Contreras, Sergio, Zehavi, Idit, Baugh, Carlton M., Nelson Padilla, Nicholas J. Smith, Idit Zehavi, Carlton M. Baugh, Peder Norberg, Padilla, Nelson   +11 more
core   +1 more source