scholarly journals Structures of Dwarf Satellites of Milky Way-like Galaxies: Morphology, Scaling Relations, and Intrinsic Shapes

2021 ◽  
Vol 922 (2) ◽  
pp. 267
Author(s):  
Scott G. Carlsten ◽  
Jenny E. Greene ◽  
Johnny P. Greco ◽  
Rachael L. Beaton ◽  
Erin Kado-Fong
Keyword(s):  
Galaxy Formation ◽  
Dwarf Galaxy ◽  
Mass Range ◽  
Scaling Relations ◽  
Early Type ◽  
Late Type ◽  
Local Volume ◽  
Stellar Feedback ◽  
Oblate Spheroids ◽  
Tidal Heating

Abstract The structure of a dwarf galaxy is an important probe of the effects of stellar feedback and environment. Using an unprecedented sample of 223 low-mass satellites from the ongoing Exploration of Local Volume Satellites survey, we explore the structures of dwarf satellites in the mass range 105.5 < M ⋆ < 108.5 M ⊙. We survey satellites around 80% of the massive, M K < − 22.4 mag, hosts in the Local Volume (LV). Our sample of dwarf satellites is complete to luminosities of M V <−9 mag and surface brightness μ 0,V < 26.5 mag arcsec−2 within at least ∼200 projected kpc of the hosts. For this sample, we find a median satellite luminosity of M V = −12.4 mag, median size of r e = 560 pc, median ellipticity of ϵ = 0.30, and median Sérsic index of n = 0.72. We separate the satellites into late- and early-type (29.6% and 70.4%, respectively). The mass–size relations are very similar between them within ∼5%, which indicates that the quenching and transformation of a late-type dwarf into an early-type one involves only very mild size evolution. Considering the distribution of apparent ellipticities, we infer the intrinsic shapes of the early- and late-type samples. Combining with literature samples, we find that both types of dwarfs are described roughly as oblate spheroids that get more spherical at fainter luminosities, but early-types are always rounder at fixed luminosity. Finally, we compare the LV satellites with dwarf samples from the cores of the Virgo and Fornax clusters. We find that the cluster satellites show similar scaling relations to the LV early-type dwarfs but are roughly 10% larger at fixed mass, which we interpret as being due to tidal heating in the cluster environments. The dwarf structure results presented here are a useful reference for simulations of dwarf galaxy formation and the transformation of dwarf irregulars into spheroidals.

scholarly journals A Simulation of Galaxy Formation by Radiation-SPH

2003 ◽  
Vol 208 ◽  
pp. 323-330
Author(s):  
Hajime Susa ◽  
Masayuki Umemura
Keyword(s):  
Star Formation ◽  
Radiation Field ◽  
Galaxy Formation ◽  
Background Radiation ◽  
Early Type ◽  
Late Type ◽  
Lower Redshift

We investigate galaxy formation with Radiation-SPH simulations in order to find the effects of ultraviolet background radiation field on the star formation in the forming galaxies. We find the ultraviolet background radiation field can delay the star formation in protogalactic clouds, especially at low redshift (z < 2). This result suggests that galaxies formed at lower redshift tend to be late type galaxies, and early type galaxies tend to be formed at higher redshift.

scholarly journals The dustier early-type galaxies deviate from late-type galaxies’ scaling relations

2016 ◽  
Vol 461 (3) ◽  
pp. 2856-2866 ◽  
Author(s):  
S. Lianou ◽  
E. Xilouris ◽  
S. C. Madden ◽  
P. Barmby
Keyword(s):  
Scaling Relations ◽  
Early Type ◽  
Late Type

scholarly journals Geometrical Parameters of E+S Pairs

1990 ◽  
Vol 124 ◽  
pp. 47-51
Author(s):  
Roberto Rampazzo ◽  
Jack W. Sulentic
Keyword(s):  
Angular Momentum ◽  
Galaxy Formation ◽  
Environmental Conditions ◽  
Geometrical Parameters ◽  
Early Type ◽  
Late Type ◽  
Factors Affecting

• Clues Concerning Galaxy Formation. Local environmental conditions (i.e. density and angular momentum properties of protogalactic clouds) are thought to be factors affecting the ultimate morphology of a galaxy. The existence of significant numbers of mixed morphology (E/SO + S) pairs of galaxies would represent a direct challenge to this idea unless all early-type components are formed by mergers. We wish to isolate candidate E+S pairs for detailed study with several questions in mind:a) Are most of the pairs true E+S systems OR, as the theory would suggest more morphologically concordant pairs involving primarily late-type or disky galaxies alone (i.e. misclassified lenticulars)?b) Assuming that many of the pairs are E+S, do their properties differ in any way from E and S galaxies in the field?c) Is their evidence that E galaxies in mixed pairs are preferentially merger products?

scholarly journals Stellar Feedback in Dwarf Galaxy Formation

Science ◽  
2008 ◽  
Vol 319 (5860) ◽  
pp. 174-177 ◽  
Author(s):  
S. Mashchenko ◽  
J. Wadsley ◽  
H. M. P. Couchman
Keyword(s):  
Galaxy Formation ◽  
Dwarf Galaxy ◽  
Stellar Feedback

scholarly journals Baryon-induced dark matter cores in the eagle simulations

2019 ◽  
Vol 488 (2) ◽  
pp. 2387-2404 ◽  
Author(s):  
Alejandro Benítez-Llambay ◽  
Carlos S Frenk ◽  
Aaron D Ludlow ◽  
Julio F Navarro
Keyword(s):  
Dark Matter ◽  
Gravitational Potential ◽  
Galaxy Formation ◽  
Dwarf Galaxy ◽  
Critical Role ◽  
Substantial Reduction ◽  
Extended Period ◽  
Mass Range ◽  
Core Formation ◽  
Gas Removal

ABSTRACT We examine the formation of dark matter (DM) cores in dwarf galaxies simulated with the eagle model of galaxy formation. As in earlier work, we find that the star formation (SF) gas density threshold (ρth) plays a critical role. At low thresholds (LT), gas is unable to reach densities high enough to dominate the gravitational potential before being dispersed by feedback from supernovae. LT runs show little effect on the inner DM profile, even in systems with extended and bursty SF, two ingredients often cited as critical for core formation. For higher thresholds, gas is able to dominate the gravitational potential before being ejected by feedback. This can lead to a substantial reduction in the inner DM content, but only if the gas is gravitationally important over an extended period of time, allowing the halo to contract before gas removal. Rapid assembly and removal of gas in short SF bursts is less effective at altering the inner DM content. Subsequent gas accretion may draw DM back in and reform a cusp, unless SF is bursty enough to prevent it, preserving the core. Thus, for the eagle SF + feedback model, there is no simple relation between core formation and SF history, contrary to recent claims. The dependence of the inner DM content of dwarfs on ρth hinders robust predictions and the interpretation of observations. A simulation of a $(12 \rm \ Mpc)^3$ volume with high ρth results in dwarfs with sizeable cores over a limited halo mass range, but with insufficient variety in mass profiles to explain the observed diversity of dwarf galaxy rotation curves.

scholarly journals Active galactic nucleus and dwarf galaxy gas kinematics

2020 ◽  
Vol 498 (3) ◽  
pp. 4562-4576 ◽  
Author(s):  
Christina M Manzano-King ◽  
Gabriela Canalizo
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
Dwarf Galaxies ◽  
Dwarf Galaxy ◽  
Strong Association ◽  
Mass Range ◽  
Mass Relation ◽  
Ionized Gas ◽  
Gas Kinematics ◽  
Counter Rotation

ABSTRACT We present spatially resolved kinematic measurements of stellar and ionized gas components of dwarf galaxies in the stellar mass range $10^{8.5}\!-\!10^{10} \, \mathrm{M}_{\odot }$, selected from Sloan Digital Sky Survey DR7 and DR8 and followed up with Keck/Low-Resolution Imaging Spectrometer spectroscopy. We study the potential effects of active galactic nuclei (AGNs) on Galaxy-wide gas kinematics by comparing rotation curves of 26 Galaxies containing AGNs, and 19 control Galaxies with no optical or infrared signs of AGNs. We find a strong association between AGN activity and disturbed gas kinematics in the host Galaxies. While star-forming Galaxies in this sample tend to have orderly gas discs that co-rotate with the stars, 73 per cent of the AGNs have disturbed gas. We find that 5 out of 45 Galaxies have gaseous components in counter-rotation with their stars, and all Galaxies exhibiting counter-rotation contain AGNs. Six out of seven isolated Galaxies with disturbed ionized gas host AGNs. At least three AGNs fall clearly below the stellar–halo mass relation, which could be interpreted as evidence for ongoing star formation suppression. Taken together, these results provide new evidence supporting the ability of AGN to influence gas kinematics and suppress star formation in dwarf galaxies. This further demonstrates the importance of including AGN as a feedback mechanism in galaxy formation models in the low-mass regime.

scholarly journals Associations of dwarf galaxies in a ΛCDM Universe

2020 ◽  
Vol 499 (4) ◽  
pp. 5932-5940
Author(s):  
C Yamila Yaryura ◽  
Mario G Abadi ◽  
Stefan Gottlöber ◽  
Noam I Libeskind ◽  
Sofía A Cora ◽  
...  
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Cold Dark Matter ◽  
Velocity Dispersion ◽  
Dwarf Galaxies ◽  
Dwarf Galaxy ◽  
Local Volume ◽  
Λcdm Model ◽  
First Time ◽  
Maximum Threshold

ABSTRACT Associations of dwarf galaxies are loose systems composed exclusively of dwarf galaxies. These systems were identified in the Local Volume for the first time more than 30 yr ago. We study these systems in the cosmological framework of the Λ cold dark matter (ΛCDM) model. We consider the Small MultiDark Planck simulation and populate its dark matter haloes by applying the semi-analytic model of galaxy formation SAG. We identify galaxy systems using a friends-of-friends algorithm with a linking length equal to $b=0.4 \, {\rm Mpc}\, h^{-1}$ to reproduce the size of dwarf galaxy associations detected in the Local Volume. Our samples of dwarf systems are built up removing those systems that have one or more galaxies with stellar mass larger than a maximum threshold Mmax. We analyse three different samples defined by ${\rm log}_{10}(M_{\rm max}[{\rm M}_{\odot }\, h^{-1}]) = 8.5, 9.0$, and 9.5. On average, our systems have typical sizes of $\sim 0.2\, {\rm Mpc}\, h^{-1}$, velocity dispersion of $\sim 30 {\rm km\, s^{-1}}$, and estimated total mass of $\sim 10^{11} {\rm M}_{\odot }\, h^{-1}$. Such large typical sizes suggest that individual members of a given dwarf association reside in different dark matter haloes and are generally not substructures of any other halo. Indeed, in more than 90 per cent of our dwarf systems their individual members inhabit different dark matter haloes, while only in the remaining 10 per cent members do reside in the same halo. Our results indicate that the ΛCDM model can naturally reproduce the existence and properties of dwarf galaxies’ associations without much difficulty.

scholarly journals A tidal tale: detection of several stellar streams in the environment of NGC 1052

2019 ◽  
Vol 624 ◽  
pp. L6 ◽  
Author(s):  
Oliver Müller ◽  
R. Michael Rich ◽  
Javier Román ◽  
Mustafa K. Yıldız ◽  
Michal Bílek ◽  
...  
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Surface Brightness ◽  
Dwarf Galaxy ◽  
Early Type ◽  
Tidal Interaction ◽  
Low Surface Brightness ◽  
Stellar Streams ◽  
Early Type Galaxy ◽  
Band Image

The possible existence of two dark-matter-free galaxies (NGC 1052-DF2 and NGC 1052-DF4) in the field of the early-type galaxy NGC 1052 presents a challenge to theories of dwarf galaxy formation according to the current cosmological paradigm. We carried out a search for signatures of past interactions connected to the putative hosts of NGC 1052-DF2 and NGC 1052-DF4 using a very deep L-band image obtained with the 0.7 m Jeanne Rich telescope that reach a surface brightness limit of 28.5 mag arcsec−2 in the r band. We found several low-surface brightness features, possibly consistent with an ongoing merger history in this group. We find a tidal interaction between NGC 1052 and NGC 1047, confirming a physical association. Furthermore, we find a stellar loop around NGC 1052 in the direction of NGC 1042 and a stellar stream pointing in the direction of NGC 1052-DF2, but they are not directly connected. We find no evidence for a recent tidal interaction for NGC 1052-DF2 and NGC 1052-DF4. No LSB features have been uncovered around the spiral galaxy NGC 1042, which leaves the association (physical or projected) between NGC 1052 and NGC 1042 ambiguous, although they have similar radial velocities. Their association will only be established when accurate distances to both objects have been measured.

scholarly journals SDSS-IV MaNGA: radial gradients in stellar population properties of early-type and late-type galaxies

2021 ◽  
Vol 502 (4) ◽  
pp. 5508-5527
Author(s):  
Taniya Parikh ◽  
Daniel Thomas ◽  
Claudia Maraston ◽  
Kyle B Westfall ◽  
Brett H Andrews ◽  
...  
Keyword(s):  
Stellar Population ◽  
Mass Range ◽  
Mass Relation ◽  
Individual Element ◽  
Late Type ◽  
Element Abundances ◽  
Entire Mass Range ◽  
Strong Gradient ◽  
Star Formation Histories ◽  
Absorption Features

ABSTRACT We derive ages, metallicities, and individual element abundances of early- and late-type galaxies (ETGs and LTGs) out to 1.5 Re. We study a large sample of 1900 galaxies spanning 8.6–11.3 log M/M⊙ in stellar mass, through key absorption features in stacked spectra from the SDSS-IV/MaNGA survey. We use mock galaxy spectra with extended star formation histories to validate our method for LTGs and use corrections to convert the derived ages into luminosity- and mass-weighted quantities. We find flat age and negative metallicity gradients for ETGs and negative age and negative metallicity gradients for LTGs. Age gradients in LTGs steepen with increasing galaxy mass, from −0.05 ± 0.11 log Gyr/Re for the lowest mass galaxies to −0.82 ± 0.08 log Gyr/Re for the highest mass ones. This strong gradient–mass relation has a slope of −0.70 ± 0.18. Comparing local age and metallicity gradients with the velocity dispersion σ within galaxies against the global relation with σ shows that internal processes regulate metallicity in ETGs but not age, and vice versa for LTGs. We further find that metallicity gradients with respect to local σ show a much stronger dependence on galaxy mass than radial metallicity gradients. Both galaxy types display flat [C/Fe] and [Mg/Fe], and negative [Na/Fe] gradients, whereas only LTGs display gradients in [Ca/Fe] and [Ti/Fe]. ETGs have increasingly steep [Na/Fe] gradients with local σ reaching 6.50 ± 0.78 dex/log km s−1 for the highest masses. [Na/Fe] ratios are correlated with metallicity for both galaxy types across the entire mass range in our sample, providing support for metallicity-dependent supernova yields.

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