scholarly journals NIHAO XXIV: rotation- or pressure-supported systems? Simulated Ultra Diffuse Galaxies show a broad distribution in their stellar kinematics

2020 ◽  
Vol 497 (4) ◽  
pp. 4282-4292
Author(s):  
Salvador Cardona-Barrero ◽  
Arianna Di Cintio ◽  
Christopher B A Brook ◽  
Tomas Ruiz-Lara ◽  
Michael A Beasley ◽  
...  
Keyword(s):  
Galaxy Evolution ◽  
Dark Matter Halo ◽  
Stellar Kinematics ◽  
Broad Distribution ◽  
Hydrodynamical Simulation ◽  
Low Surface Brightness ◽  
Astrophysical Objects ◽  
Comprehensive Survey ◽  
Gas Accretion ◽  
State Pressure

ABSTRACT In recent years, a new window on galaxy evolution opened, thanks to the increasing discovery of galaxies with a low-surface brightness, such as Ultra Diffuse Galaxies (UDGs). The formation mechanism of these systems is still a much debated question and so are their kinematical properties. In this work, we address this topic by analysing the stellar kinematics of isolated UDGs formed in the hydrodynamical simulation suite Numerical Investigation of a Hundred Astrophysical Objects (NIHAO). We construct projected line-of-sight velocity and velocity dispersion maps to compute the projected specific angular momentum, λR, to characterize the kinematical support of the stars in these galaxies. We found that UDGs cover a broad distribution, ranging from dispersion to rotation-supported galaxies, with similar abundances in both regimes. The degree of rotation support of simulated UDGs correlates with several properties such as galaxy morphology, higher H i fractions, and larger effective radii with respect to the dispersion-supported group, while the dark matter halo spin and mass accretion history are similar among the two populations. We demonstrate that the alignment of the infalling baryons into the protogalaxy at early z is the principal driver of the z = 0 stellar kinematic state: pressure-supported isolated UDGs form via misaligned gas accretion while rotation-supported ones build up their baryons in an ordered manner. Accounting for random inclination effects, we predict that a comprehensive survey will find nearly half of field UDGs to have rotationally supported stellar discs, when selecting UDGs with effective radius larger than 1 kpc.

scholarly journals Linking Clustering Properties and the Evolution of Low Surface Brightness Galaxies

2007 ◽  
Vol 3 (S244) ◽  
pp. 274-278
Author(s):  
Dominik J. Bomans ◽  
S. Dominik Rosenbaum
Keyword(s):  
Galaxy Evolution ◽  
Surface Brightness ◽  
Large Scale ◽  
High Surface ◽  
Sloan Digital Sky Survey ◽  
Dark Matter Halo ◽  
Sky Survey ◽  
Low Surface Brightness ◽  
Low Surface Brightness Galaxies ◽  
Lsb Galaxies

AbstractThe reasons for the presence of two branches of galaxy evolution, one producing high surface brightness disks and one creating low surface brightness disks, is still unknown. Possible are the imprint of the properties of the dark matter halo, as well as evolutionary effects. In this paper we present an analysis of the clustering properties of LSB and HSB galaxies using the Sloan Digital Sky Survey. We show that LSB galaxies reside in regions of lower galaxy density than HSB galaxies on all scales between 0.8 and 8 Mpc, from scales of galaxy pairs to filaments of the Large Scale Structure. This implies a probable scenario of LSB galaxies preferentially forming as a result of local peaks in the large-scale valleys of the primordial density distribution.

scholarly journals Galaxy Dynamics: Secular Evolution and Accretion

2010 ◽  
Vol 6 (S271) ◽  
pp. 119-126 ◽  
Author(s):  
Francoise Combes
Keyword(s):  
Angular Momentum ◽  
Galaxy Evolution ◽  
Resonant Scattering ◽  
Relative Role ◽  
Radial Migration ◽  
Galaxy Dynamics ◽  
Secular Evolution ◽  
Minor Mergers ◽  
Gas Accretion

AbstractRecent results are reviewed on galaxy dynamics, bar evolution, destruction and re-formation, cold gas accretion, gas radial flows and AGN fueling, minor mergers. Some problems of galaxy evolution are discussed in particular, exchange of angular momentum, radial migration through resonant scattering, and consequences on abundance gradients, the frequency of bulgeless galaxies, and the relative role of secular evolution and hierarchical formation.

scholarly journals The formation of ultradiffuse galaxies in clusters

2020 ◽  
Vol 494 (2) ◽  
pp. 1848-1858 ◽  
Author(s):  
Laura V Sales ◽  
Julio F Navarro ◽  
Louis Peñafiel ◽  
Eric W Peng ◽  
Sungsoon Lim ◽  
...  
Keyword(s):  
Surface Brightness ◽  
Velocity Dispersion ◽  
Stellar Mass ◽  
Matter Content ◽  
Lower Velocity ◽  
Large Size ◽  
Hydrodynamical Simulation ◽  
Low Surface Brightness ◽  
Mass Size ◽  
Low Surface Brightness Galaxies

ABSTRACT We use the IllustrisTNG cosmological hydrodynamical simulation to study the formation of ultradiffuse galaxies (UDGs) in galaxy clusters. We supplement the simulations with a realistic mass–size relation for galaxies at the time of infall into the cluster, as well as an analytical model to describe the tidally induced evolution of their stellar mass, velocity dispersion, and size. The model assumes ‘cuspy’ NFW haloes and, contrary to recent claims, has no difficulty reproducing the observed number of UDGs in clusters. Our results further suggest that the UDG population consists of a mixture of ‘normal’ low surface brightness galaxies such as those found in the field (‘born’ UDGs, or B-UDGs), as well as a distinct population that owe their large size and low surface brightness to the effects of cluster tides (‘tidal’, or T-UDGs). The simulations indicate that T-UDGs entered the cluster earlier and should be more prevalent than B-UDGs near the cluster centres. T-UDGs should also have, at given stellar mass, lower velocity dispersion, higher metallicities, and lower dark matter content than B-UDGs. Our results suggest that systems like DF-44 are consistent with having been born as UDGs, while others such as DF2, DF4, and VLSB-D are possibly extreme T-UDG examples.

scholarly journals Milky Way analogues in MaNGA: multiparameter homogeneity and comparison to the Milky Way

2019 ◽  
Vol 491 (3) ◽  
pp. 3672-3701 ◽  
Author(s):  
N Boardman ◽  
G Zasowski ◽  
A Seth ◽  
J Newman ◽  
B Andrews ◽  
...  
Keyword(s):  
Galaxy Evolution ◽  
Milky Way ◽  
Central Star ◽  
Stellar Kinematics ◽  
Star Forming ◽  
Wide Range ◽  
The Galaxy ◽  
Central Regions ◽  
Galaxy Population ◽  
Stellar Masses

ABSTRACT The Milky Way provides an ideal laboratory to test our understanding of galaxy evolution, owing to our ability to observe our Galaxy over fine scales. However, connecting the Galaxy to the wider galaxy population remains difficult, due to the challenges posed by our internal perspective and to the different observational techniques employed. Here, we present a sample of galaxies identified as Milky Way analogues on the basis of their stellar masses and bulge-to-total ratios, observed as part of the Mapping Nearby Galaxies at Apache Point Observatory survey. We analyse the galaxies in terms of their stellar kinematics and populations as well as their ionized gas contents. We find our sample to contain generally young stellar populations in their outskirts. However, we find a wide range of stellar ages in their central regions, and we detect central active galactic nucleus-like or composite-like activity in roughly half of the sample galaxies, with the other half consisting of galaxies with central star-forming emission or emission consistent with old stars. We measure gradients in gas metallicity and stellar metallicity that are generally flatter in physical units than those measured for the Milky Way; however, we find far better agreement with the Milky Way when scaling gradients by galaxies’ disc scale lengths. From this, we argue much of the discrepancy in metallicity gradients to be due to the relative compactness of the Milky Way, with differences in observing perspective also likely to be a factor.

scholarly journals LOFAR view of NGC 3998, a sputtering AGN

2020 ◽  
Vol 634 ◽  
pp. A108 ◽  
Author(s):  
Sarrvesh S. Sridhar ◽  
Raffaella Morganti ◽  
Kristina Nyland ◽  
Bradley S. Frank ◽  
Jeremy Harwood ◽  
...  
Keyword(s):  
Low Power ◽  
Galaxy Evolution ◽  
Spectral Index ◽  
Surface Brightness ◽  
Large Scale ◽  
Radio Sources ◽  
The Core ◽  
Low Surface Brightness ◽  
High Turbulence ◽  
The Rich

Low-power radio sources dominate the radio sky. They tend to be small in size and dominated by their cores, but the origin of their properties and the evolution of their radio plasma are not well constrained. Interestingly, there is mounting evidence that low-power radio sources can significantly affect their surrounding gaseous medium and may therefore be more relevant for galaxy evolution than previously thought. In this paper, we present low radio frequency observations obtained with LOFAR at 147 MHz of the radio source hosted by NGC 3998. This is a rare example of a low-power source that is extremely dominated by its core, but that has two large-scale lobes of low surface brightness. We combine the new 147 MHz image with available 1400 MHz data to derive the spectral index over the source. Despite the low surface brightness, reminiscent of remnant structures, the lobes show an optically thin synchrotron spectral index (∼0.6). We interpret this as being due to rapid decollimation of the jets close to the core, to high turbulence of the plasma flow, and to entrainment of thermal gas. This could be the result of intermittent activity of the central active galactic nucleus, or, more likely, temporary disruption of the jet due to the interaction of the jet with the rich circumnuclear interstellar matter. Both would result in sputtering energy injection from the core, which would keep the lobes fed, albeit at a low rate. We discuss these results in connection with the properties of low-power radio sources in general. Our findings show that amorphous low surface brightness lobes should not be interpreted by default as remnant structures. Large deep surveys (in particular the LOFAR 150 MHz LoTSS and the recently started 1400 MHz Apertif survey) will identify a growing number of objects similar to NGC 3998 where these ideas can be further tested.

scholarly journals The shape of the dark matter halo revealed from a hypervelocity star

2019 ◽  
Vol 14 (S353) ◽  
pp. 96-100
Author(s):  
Kohei Hattori ◽  
Monica Valluri
Keyword(s):  
Dark Matter ◽  
Posterior Distribution ◽  
Galactic Center ◽  
Dark Matter Halo ◽  
Velocity Data ◽  
Broad Distribution ◽  
Giant Star ◽  
Circular Velocity ◽  
Galactic Dark Matter ◽  
Radial Orbit

AbstractA recently discovered young, high-velocity giant star J01020100-7122208 is a good candidate of hypervelocity star ejected from the Galactic center, although it has a bound orbit. If we assume that this star was ejected from the Galactic center, it can be used to constrain the Galactic potential, because the deviation of its orbit from a purely radial orbit informs us of the torque that this star has received. Based on this assumption, we estimate the flattening of the Galactic dark matter halo by using the Gaia DR2 data and the circular velocity data. Our Bayesian analysis shows that the orbit of J01020100-7122208 favors a prolate halo within ~ 10 kpc from the Galactic center. The posterior distribution of the density flattening q shows a broad distribution at q ≳ 1 and peaks at q ≃ 1.5. Also, 98.5% of the posterior distribution is located at q > 1, highly disfavoring an oblate halo.

scholarly journals Near-infrared observations of star formation and gas flows in the NUGA galaxy NGC 1365

2019 ◽  
Vol 622 ◽  
pp. A128 ◽  
Author(s):  
Nastaran Fazeli ◽  
Gerold Busch ◽  
Mónica Valencia-S. ◽  
Andreas Eckart ◽  
Michal Zajaček ◽  
...  
Keyword(s):  
Star Formation ◽  
Emission Line ◽  
Galaxy Evolution ◽  
Large Scale ◽  
Near Infrared ◽  
Molecular Gas ◽  
Nuclear Region ◽  
Stellar Kinematics ◽  
Hydrogen Recombination ◽  
Ngc 1365

In the framework of understanding the gas and stellar kinematics and their relations to AGNs and galaxy evolution scenarios, we present spatially resolved distributions and kinematics of the stars and gas in the central ∼800 pc radius of the nearby Seyfert galaxy NGC 1365. We obtained H + K- and K-band near-infrared (NIR) integral-field observations from VLT/SINFONI. Our results reveal strong broad and narrow emission-line components of ionized gas (hydrogen recombination lines Paα and Brγ) in the nuclear region, as well as hot dust with a temperature of ∼1300 K, both typical for type-1 AGNs. From MBH − σ* and the broad components of hydrogen recombination lines, we find a black-hole mass of (5 − 10)×106 M⊙. In the central ∼800 pc, we find a hot molecular gas mass of ∼615 M⊙, which corresponds to a cold molecular gas reservoir of (2 − 8)×108 M⊙. However, there is a molecular gas deficiency in the nuclear region. The gas and stellar-velocity maps both show rotation patterns consistent with the large-scale rotation of the galaxy. However, the gaseous and stellar kinematics show deviations from pure disk rotation, which suggest streaming motions in the central < 200 pc and a velocity twist at the location of the ring which indicates deviations in disk and ring rotation velocities in accordance with published CO kinematics. We detect a blueshifted emission line split in Paα, associated with the nuclear region only. We investigate the star-formation properties of the hot spots in the circumnuclear ring which have starburst ages of ≲10 Myr and find indications for an age gradient on the western side of the ring. In addition, our high-resolution data reveal further substructure within this ring which also shows enhanced star forming activity close to the nucleus.

scholarly journals Numerical simulations of galaxy evolution in cosmological context

2008 ◽  
Vol 4 (S254) ◽  
pp. 429-434
Author(s):  
Marie Martig ◽  
Frédéric Bournaud ◽  
Romain Teyssier
Keyword(s):  
Galaxy Evolution ◽  
Large Scale ◽  
Physical Processes ◽  
Cosmological Simulations ◽  
Cosmological Context ◽  
First Results ◽  
Gas Accretion ◽  
The Universe ◽  
Very High ◽  
Internal Evolution

AbstractLarge volume cosmological simulations succeed in reproducing the large-scale structure of the Universe. However, they lack resolution and may not take into account all relevant physical processes to test if the detail properties of galaxies can be explained by the CDM paradigm. On the other hand, galaxy-scale simulations could resolve this in a robust way but do not usually include a realistic cosmological context.To study galaxy evolution in cosmological context, we use a new method that consists in coupling cosmological simulations and galactic scale simulations. For this, we record merger and gas accretion histories from cosmological simulations and re-simulate at very high resolution the evolution of baryons and dark matter within the virial radius of a target galaxy. This allows us for example to better take into account gas evolution and associated star formation, to finely study the internal evolution of galaxies and their disks in a realistic cosmological context.We aim at obtaining a statistical view on galaxy evolution from z ≃ 2 to 0, and we present here the first results of the study: we mainly stress the importance of taking into account gas accretion along filaments to understand galaxy evolution.

scholarly journals Probing the QSO host galaxy evolution through the gas metallicity

2012 ◽  
Vol 8 (S295) ◽  
pp. 269-269
Author(s):  
B. Husemann ◽  
L. Wisotzki ◽  
K. Jahnke ◽  
S. F. Sánchez ◽  
D. Nugroho
Keyword(s):  
Gas Phase ◽  
Galaxy Evolution ◽  
Host Galaxy ◽  
Host Galaxies ◽  
Spatially Resolved ◽  
Gas Accretion

AbstractWe use the spatially resolved gas-phase metallicity as a new diagnostic for tagging recent interactions in QSO host galaxies. With this technique we also identified a QSO with extremely low gas-phase metallicity as likely evidence for gas accretion from the environment.

scholarly journals Mass and kinematics of late-type galaxies (1.3 < z < 3.3) from the VVDS

2007 ◽  
Vol 3 (S245) ◽  
pp. 467-468
Author(s):  
M. Lemoine-Busserolle ◽  
T. Contini ◽  
O. Le Fèvre ◽  
M. Kissler-Patig ◽  
Keyword(s):  
Galaxy Evolution ◽  
High Redshift ◽  
Formation Rate ◽  
Nir Spectroscopy ◽  
Optical Emission ◽  
Spectroscopic Studies ◽  
Dark Matter Halo ◽  
Late Type ◽  
Galaxy Dynamics ◽  
Galaxy Kinematics

AbstractGalaxy kinematics at early epochs give a key insight into the assembly of mass. Redshifts z ~ 1 − 3 appear to be the peak of the star formation rate of the Universe, possibly corresponding to the maximal merger activity. 2D velocity fields of late-type galaxies can be used to put important constraints on its total mass and hence on its dark matter halo. As dark halos are thought to govern the rate of galaxy evolution, securing reliable mass measurements for early systems at high redshift is a fundamental observational goal. In addition, accurate inner shape rotation curves, only drawed by 3D spectroscopic studies, should allow to disentangle cosmological scenarii. In the purpose of probing the evolution in masses and mass-to-light ratios of the galaxies during an epoch of expected strong evolution, and setting constrains on their formation and evolution, we present preliminary results obtained from Integral Field NIR Spectroscopy with SINFONI/VLT of a first sample of ten high-z (1.3 < z < 3.3) late-type galaxies selected in the VIMOS/VLT Deep Survey (VVDS). The SINFONI NIR-IFU mode allow to spatially resolve galaxy dynamics using bright rest-frame optical emission lines, in order to perform statistical studies of dynamical masses at this early epochs.

Sign in / Sign up

Export Citation Format

Share Document