UWCScholar :: Browsing by Author "Dave, Romeel"

Browsing by Author "Dave, Romeel"

Now showing 1 - 20 of 41

Aligned metal absorbers and the ultraviolet background at the end of reionization
(Oxford University Press, 2018) Doughty, Caitlin; Finlator, Kristian; Oppenheimer, Benjamin D.; Dave, Romeel; Zackrisson, Erik
We use observations of spatially-aligned C ii, C iv, Si ii, Si iv, and O i absorbers to probe the slope and intensity of the ultraviolet background (UVB) at z ∼ 6. We accom- plish this by comparing observations with predictions from a cosmological hydrody- namic simulation using three trial UVBs applied in post-processing: a spectrally soft, fluctuating UVB calculated using multi-frequency radiative transfer; a soft, spatially- uniform UVB; and a hard, spatially-uniform “quasars-only” model. When considering our paired high-ionization absorbers (Civ/Siiv), the observed statistics strongly prefer the hard, spatially-uniform UVB. This echoes recent findings that cosmological sim- ulations generically underproduce strong C iv absorbers at z > 5. A single low/high ionization pair (Si ii/Si iv), by contrast, shows a preference for the HM12 UVB, while two more (C ii/C iv and O i/C iv) show no preference for any of the three UVBs. Despite this, future observations of specific absorbers, particularly Si iv/C iv, with next-generation telescopes probing to lower column densities should yield tighter con- ts on the UVB.
Black hole - galaxy correlations without self-regulation
(American Astronomical Society, 2013) Angles-Alcazar, Daniel; Ozel, Feryal; Dave, Romeel
Recent models of black hole growth in a cosmological context have forwarded a paradigm in which the growth is self-regulated by feedback from the black hole itself. Here we use cosmological zoom simulations of galaxy formation down to z =2 to show that such strong self-regulation is required in the popular spherical Bondi accretion model, but that a plausible alternative model in which black hole growth is limited by galaxy-scale torques does not require self-regulation. Instead, this torque-limited accretion model yields black holes and galaxies evolving on average along the observed scaling relations by relying only on a fixed, 5% mass retention rate onto the black hole from the radius at which the accretion flow is fed. Feedback from the black hole may (and likely does) occur, but does not need to couple to galaxy-scale gas in order to regulate black hole growth. We show that this result is insensitive to variations in the initial black hole mass, stellar feedback, or other implementation details. The torque-limited model allows for high accretion rates at very early epochs (unlike the Bondi case), which if viable can help explain the rapid early growth of black holes, while by z ∼ 2 it yields Eddington factors of ∼1%–10%. This model also yields a less direct correspondence between major merger events and rapid phases of black hole growth. Instead, growth is more closely tied to cosmological disk feeding, which may help explain observational studies showing that, at least at z >~ 1, active galaxies do not preferentially show merger signatures.
The CAMELS multifield data set: Learning the universe’s fundamental parameters with artificial intelligence
(IOP, 2022) Shy, Genel; Villaescusa-Navarro, Fransisco; Anglés-Alcázar, Daniel; Dave, Romeel; Hassan, Sultan
We present the Cosmology and Astrophysics with Machine Learning Simulations (CAMELS) Multifield Data set (CMD), a collection of hundreds of thousands of 2D maps and 3D grids containing many different properties of cosmic gas, dark matter, and stars from more than 2000 distinct simulated universes at several cosmic times. The 2D maps and 3D grids represent cosmic regions that span ∼100 million light-years and have been generated from thousands of state-of-the-art hydrodynamic and gravity-only N-body simulations from the CAMELS project. Designed to train machine-learning models, CMD is the largest data set of its kind containing more than 70 TB of data. In this paper we describe CMD in detail and outline a few of its applications. We focus our attention on one such task, parameter inference, formulating the problems we face as a challenge to the community.
The circumgalactic medium from the camels simulations: Forecasting constraints on feedback processes from future Sunyaev–Zeldovich observations
(IOP Publishing, 2022) Moser, Emily; Battaglia, Nicholas; Dave, Romeel
It is important to understand the cycle of baryons through the circumgalactic medium (CGM) in the context of galaxy formation and evolution. In this study, we forecast constraints on the feedback processes heating the CGM with current and future Sunyaev–Zeldovich (SZ) observations. To constrain these processes, we use a suite of cosmological simulations, the Cosmology and Astrophysics with MachinE Learning Simulations (CAMELS). CAMELS varies four different feedback parameters of two previously existing hydrodynamical simulations, IllustrisTNG and SIMBA. We capture the dependences of SZ radial profiles on these feedback parameters with an emulator, calculate their derivatives, and forecast future constraints on these feedback parameters from upcoming experiments.
Classifying galaxies according to their H I content
(Oxford University Press, 2020) Andrianomena, Sambatra; Rafieferantsoa, Mika; Dave, Romeel
We use machine learning to classify galaxies according to their H I content, based on both their optical photometry and environmental properties. The data used for our analyses are the outputs in the range z = 0–1 from MUFASA cosmological hydrodynamic simulation. In our previous paper, where we predicted the galaxy H I content using the same input features, H I-rich galaxies were only selected for the training. In order for the predictions on real observation data to be more accurate, the classifiers built in this study will first establish if a galaxy is H I rich (⁠log(MHI/M∗)>−2⁠) before estimating its neutral hydrogen content using the regressors developed in the first paper.
The COS-Halos survey: Rationale, design and a census of circumgalactic neutral hydrogen
(IOP Publishing, 2013) Tumlinson, Jason; Thom, Christopher; Dave, Romeel; Werk, Jessica K.; Prochaska, J. Xavier; Tripp, Todd M.; Katz, Neal; Oppenheimer, Benjamin D.; Meiring, Joseph D.; Ford, Amanda Brady; O'Meara, John M.; Peeples, Molly S.; Sembach, Kenneth R.; Weinberg, David H.
We present the design and methods of the COS-Halos survey, a systematic investigation of the gaseous halos of 44 z = 0.15–0.35 galaxies using background QSOs observed with the Cosmic Origins Spectrograph aboard the Hubble Space Telescope. This survey has yielded 39 spectra of zem 0.5 QSOs with S/N ∼10–15 per resolution element. The QSO sightlines pass within 150 physical kpc of the galaxies, which span early and late types over stellar mass logM∗/M = 9.5–11.5. We find that the circumgalactic medium exhibits strong Hi, averaging 1Å in Lyα equivalent width out to 150 kpc, with 100% covering fraction for star-forming galaxies and 75% covering for passive galaxies. We find good agreement in column densities between this survey and previous studies over similar range of impact parameter. There is weak evidence for a difference between early- and late-type galaxies in the strength and distribution of Hi. Kinematics indicate that the detected material is bound to the host galaxy, such that 90% of the detected column density is confined within ±200 km s−1 of the galaxies. This material generally exists well below the halo virial temperatures at T 105 K. We evaluate a number of possible origin scenarios for the detected material, and in the end favor a simple model in which the bulk of the detected Hi arises in a bound, cool, low-density photoionized diffuse medium that is generic to all L ∗ galaxies and may harbor a total gaseous mass comparable to galactic stellar masses.
The cosmic evolution of the IMF under the Jeans conjecture with implications for massive galaxies
(Oxford University Press, 2013) Narayanan, Desika; Dave, Romeel
We examine the cosmic evolution of a stellar initial mass function (IMF) in galaxies that varies with the Jeans mass in the interstellar medium, paying particular attention to the K-band stellar mass-to-light ratio (M/LK) of present-epoch massive galaxies. We calculate the typical Jeans mass using high-resolution hydrodynamic simulations coupled with a fully radiative model for the interstellar medium (ISM), which yields a parametrization of the IMF characteristic mass as a function of galaxy star formation rate (SFR).We then calculate the star formation histories of galaxies utilizing an equilibrium galaxy growth model coupled with constraints on the star formation histories set by abundance matching models. We find that at early times, energetic coupling between dust and gas drives warm conditions in the ISM, yielding bottom-light/topheavy IMFs associated with large ISM Jeans masses for massive star-forming galaxies. Owing to the remnants of massive stars that formed during the top-heavy phases at early times, the resultant M/LK(σ) in massive galaxies at the present epoch is increased relative to the nonvarying IMF case. At late times, lower cosmic ray fluxes allow for cooler ISM temperatures in massive galaxies, and hence newly formed clusters will exhibit bottom-heavy IMFs, further increasing M/LK(σ). Our central result is hence that a given massive galaxy may go through both top-heavy and bottom-heavy IMF phases during its lifetime, though the bulk of the stars form during a top-heavy phase. Qualitatively, the variations in M/LK(σ) with galaxy mass are in agreement with observations; however, our model may not be able to account for bottom-heavy mass functions as indicated by stellar absorption features.
Cosmological baryon transfer in the SIMBA simulations
(Oxford University Press, 2019) Dave, Romeel; Borrow, Josh; Angles-Alcazar, Daniel
We present a framework for characterizing the large-scale movement of baryons relative to dark matter in cosmological simulations, requiring only the initial conditions and final state of the simulation. This is performed using the spread metric that quantifies the distance in the final conditions between initially neighbouring particles, and by analysing the baryonic content of final haloes relative to that of the initial Lagrangian regions (LRs) defined by their dark matter component. Applying this framework to the SIMBA cosmological simulations, we show that 40 per cent (10 per cent) of cosmological baryons have moved >1h−1Mpc (⁠3h−1Mpc⁠) by z = 0, primarily due to entrainment of gas by jets powered by an active galactic nucleus, with baryons moving up to 12h−1Mpc away in extreme cases. Baryons decouple from the dynamics of the dark matter component due to hydrodynamic forces, radiative cooling, and feedback processes.
A deep search for faint galaxies associated with very low-redshift C iv absorbers: A case with cold-accretion characteristics
(The American Astronomical Society, 2013) Burchett, Joseph N.; Tripp, Todd M.; Werk, Jessica K.; Howk, J. Christopher; Dave, Romeel; Prochaska, J. Xavier; Ford, Amanda Brady
Studies of QSO absorber–galaxy connections are often hindered by inadequate information on whether faint/dwarf galaxies are located near the QSO sight lines. To investigate the contribution of faint galaxies to QSO absorber populations, we are conducting a deep galaxy redshift survey near low-z Civ absorbers. Here we report a blindly detected C iv absorption system (zabs = 0.00348) in the spectrum of PG1148+549 that appears to be associated either with an edge-on dwarf galaxy with an obvious disk (UGC 6894, zgal = 0.00283) at an impact parameter of ρ = 190 kpc or with a very faint dwarf irregular galaxy at ρ = 23 kpc, which is closer to the sightline but has a larger redshift difference (zgal = 0.00107, i.e., δv = 724 km s−1). We consider various gas/galaxy associations, including infall and outflows. Based on current theoretical models, we conclude that the absorber is most likely tracing (1) the remnants of an outflow from a previous epoch, a so-called “ancient outflow”, or (2) intergalactic gas accreting onto UGC 6894, “cold mode” accretion. The latter scenario is supported by Hi synthesis imaging data that shows the rotation curve of the disk being codirectional with the velocity offset between UGC 6894 and the absorber, which is located almost directly along the major axis of the edge-on disk.
Dusty starbursts masquerading as ultra-high redshift galaxies in jwst ceers observations
(American Astronomical Society, 2023) Fontana, Adriano; Giavalisco, Mauro; Dave, Romeel
Lyman-break galaxy (LBG) candidates at z  10 are rapidly being identified in James Webb Space Telescope (JWST)/NIRCam observations. Due to the (redshifted) break produced by neutral hydrogen absorption of restframe UV photons, these sources are expected to drop out in the bluer filters while being well detected in redder filters. However, here we show that dust-enshrouded star-forming galaxies at lower redshifts (z  7) may also mimic the near-infrared (near-IR) colors of z > 10 LBGs, representing potential contaminants in LBG candidate samples. First, we analyze CEERS-DSFG-1, a NIRCam dropout undetected in the F115W and F150W filters but detected at longer wavelengths. Combining the JWST data with (sub)millimeter constraints, including deep NOEMA interferometric observations, we show that this source is a dusty star-forming galaxy (DSFG) at z ≈ 5.1. We also present a tentative 2.6σ SCUBA-2 detection at 850 μm around a recently identified z ≈ 16 LBG candidate in the same field and show that, if the emission is real and associated with this candidate, the available photometry is consistent with a z ∼ 5 dusty galaxy with strong nebular emission lines despite its blue near-IR colors.
The frequency of very young galaxies in the local Universe – II. The view from SDSS spectra
(Oxford University Press, 2019) Dave, Romeel; Mamon, Gary A.; Trevisan, Marina
Only a handful of galaxies in the local Universe appear to be very young. We estimate the fraction of very young galaxies (VYGs), defined as those with more than half their stellar masses formed within the last Gyr. We fit non-parametric star formation histories (SFHs) to ∼280 000 galaxy spectra from a flux- and volume-limited subsample of the Main Galaxy Sample (MGS) of the SDSS, which is also complete in mass-to-light ratio, thus properly accounting for passive galaxies of a given mass. The VYG fractions decrease with increasing galaxy stellar mass, from ∼50 per cent at m=108M⊙ to ∼0.1 per cent at m=1011.5M⊙⁠, with differences of up to 1 dex between the different spectral models used to estimate the SFH and on how we treat aperture effects.
The high-ion content and kinematics of low-redshift lyman limit systems
(The American Astronomical Society, 2013) Fox, Andrew J.; Lehner, Nicholas; Dave, Romeel; Tumlinson, Jason; Howk, J. Christopher; Tripp, Todd M.; Prochaska, J. Xavier; O'Meara, John M.; Werk, Jessica K.; Bordoloi, Rongmon; Katz, Neal; Oppenheimer, Benjamin D.
We study the high-ion content and kinematics of the circumgalactic medium around low-redshift galaxies using a sample of 23 Lyman limit systems (LLSs) at 0.08 < z < 0.93 observed with the Cosmic Origins Spectrograph on board the Hubble Space Telescope. In Lehner et al., we recently showed that low-z LLSs have a bimodal metallicity distribution. Here we extend that analysis to search for differences between the high-ion and kinematic properties of the metal-poor and metal-rich branches. We find that metal-rich LLSs tend to show higher O VI columns and broader O VI profiles than metal-poor LLSs. The total H I line width (Δv 90 statistic) in LLSs is not correlated with metallicity, indicating that the H I kinematics alone cannot be used to distinguish inflow from outflow and gas recycling. Among the 17 LLSs with O VI detections, all but two show evidence of kinematic sub-structure, in the form of O VI-H I centroid offsets, multiple components, or both. Using various scenarios for how the metallicities in the high-ion and low-ion phases of each LLS compare, we constrain the ionized hydrogen column in the O VI phase to lie in the range log N(H II) ~ 17.6-20. The O VI phase of LLSs is a substantial baryon reservoir, with M(high-ion) ~ 108.5-10.9 (r/150 kpc)2 M ☉, similar to the mass in the low-ion phase. Accounting for the O VI phase approximately doubles the contribution of low-z LLSs to the cosmic baryon budget.
The host haloes of O I absorbers in the reionization epoch
(Oxford University Press, 2013) Finlator, Kristian; Muñoz, Joseph A.; Dave, Romeel; Oppenheimer, B. D.; Peng Oh, S.; Özel, Feryal
We use a radiation hydrodynamic simulation of the hydrogen reionization epoch to study OI absorbers at z ∼ 6. The intergalactic medium (IGM) is reionized before it is enriched; hence, OI absorption originates within dark matter haloes. The predicted abundance of OI absorbers is in reasonable agreement with observations. At z = 10, ≈70 per cent of sightlines through atomically cooled haloes encounter a visible (NOI > 1014cm−2) column. Reionization ionizes and removes gas from haloes less massive than 108.4M , but 20 per cent of sightlines through more massive haloes encounter visible columns even at z = 5. The mass scale of absorber host haloes is 10–100 times smaller than the haloes of Lyman-break galaxies and Lyman α emitters, hence absorption probes the dominant ionizing sources more directly. OI absorbers have neutral hydrogen columns of 1019–1021 cm−2, suggesting a close resemblance between objects selected in OI and HI absorption. Finally, the absorption in the foreground of the z = 7.085 quasar ULAS J1120+0641 cannot originate in a dark matter halo because halo gas at the observed HI column density is enriched enough to violate the upper limits on the OI column. By contrast, gas at less than one-third the cosmic mean density satisfies the constraints. Hence, the foreground absorption likely originates in the IGM.
The impact of environment and mergers on the H I content of galaxies in hydrodynamic simulations
(University of the Western Cape, 2015) Rafieferantsoa, Mika Harisetry; Dave, Romeel
We quantitatively examine the effects of merger and environment within a cosmological hydrodynamic simulation. We show that our simulation model broadly reproduces the observed scatter in H I at a given stellar mass as quantified by the HI mass function in bins of stellar mass, as well as the H I richness versus local galaxy density. The predicted H I fluctuations and environmental effects are roughly consistent with data, though some discrepancies are present at group scales. For satellite galaxies in & 1012Mhalos, the H I richness distribution is bimodal and drops towards the largest halo masses. The depletion rate of H I once a galaxy enters a more massive halo is more rapid at higher halo mass, in contrast to the specific star formation rate which shows much less variation in the attenuation rate versus halo mass. This suggests that, up to halo mass scales probed here (. 1014M), star formation is mainly attenuated by starvation, but H I is additionally removed by stripping once a hot gaseous halo is present. In low mass halos, the H I richness of satellites is independent of radius, while in high mass halos they become gas-poor towards the center, confirming the increasing strength of the stripping with halo mass. By tracking the progenitors of galaxies, we show that the gas fraction of satellite and central galaxiesdecreases from z =5 ! 0, tracking each other until z⇠1 after which the satellites’ H I content drops much more quickly, particularly for the highest halo masses. Mergers somewhat increase the H I richness and its scatter about the mean relation, but these variations are consistent with arising form inflow fluctuations, unlike in the case of star formation where mergers boost it above that expected from inflow fluctuations. In short, our simulations suggest that the H I content in galaxies is determined by their ability to accrete gas from their surroundings, with stripping effects playing a driving role once a hot gaseous halo is present.
The impact of quenching on galaxy profiles in the SIMBA simulation
(Oxford University Press, 2020) Dave, Romeel; Appleby, Sarah; Kraljic, Katarina
We study specific star formation rate (sSFR) and gas profiles of star-forming (SF) and green valley (GV) galaxies in the SIMBA cosmological hydrodynamic simulation. SF galaxy half-light radii (Rhalf) at z = 0 and their evolution (∝(1 + z)−0.78) agree with observations. Passive galaxy Rhalf agree with observations at high redshift, but by z = 0 are too large, owing to numerical heating. We compare SIMBAz = 0 sSFR radial profiles for SF and GV galaxies to observations. SIMBA shows strong central depressions in star formation rate (SFR), sSFR, and gas fraction in GV galaxies and massive SF systems, qualitatively as observed, owing to black hole X-ray feedback, which pushes central gas outwards.
The impact of the connectivity of the cosmic web on the physical properties of galaxies at its nodes
(Oxford University Press, 2019) Dave, Romeel; Kraljic, Katarina; Pichon, Christophe
We investigate the impact of the number of filaments connected to the nodes of the cosmic web on the physical properties of their galaxies using the Sloan Digital Sky Survey. We compare these measurements to the cosmological hydrodynamical simulations H ORIZON-(NO)AGN and SIMBA. We find that more massive galaxies are more connected, in qualitative agreement with theoretical predictions and measurements in dark-matter-only simulations. The star formation activity and morphology of observed galaxies both display some dependence on the connectivity of the cosmic web at a fixed stellar mass: Less star forming and less rotation supported galaxies also tend to have higher connectivity.
Inferring halo masses with graph neural networks
(Institute of Physics, 2022) Villanueva-Domingo, Pablo; Villaescusa-Navarro, Francisco; Dave, Romeel
Understanding the halo–galaxy connection is fundamental in order to improve our knowledge on the nature and properties of dark matter. In this work, we build a model that infers the mass of a halo given the positions, velocities, stellar masses, and radii of the galaxies it hosts. In order to capture information from correlations among galaxy properties and their phase space, we use Graph Neural Networks (GNNs), which are designed to work with irregular and sparse data. We train our models on galaxies from more than 2000 state-of-the-art simulations from the Cosmology and Astrophysics with MachinE Learning Simulations project. Our model, which accounts for cosmological and astrophysical uncertainties, is able to constrain the masses of the halos with a ∼0.2 dex accuracy. Furthermore, a GNN trained on a suite of simulations is able to preserve part of its accuracy when tested on simulations run with a different code that utilizes a distinct subgrid physics model, showing the robustness of our method.
Jet feedback and the photon underproduction crisis in SIMBA
(Oxford University Press, 2020-10-01) Dave, Romeel; Christiansen, Jacob; Sorini, Daniele; Angles-Alc ´ azar, Daniel
We examine the impact of black hole jet feedback on the properties of the low-redshift intergalactic medium (IGM) in the SIMBA simulation, with a focus on the Lyα forest mean flux decrement DA. Without jet feedback, we confirm the photon underproduction crisis (PUC) in which H I at z = 0 must be increased by 6 times over the Haardt & Madau value in order to match the observed DA. Turning on jet feedback lowers this discrepancy to ∼2.5 times, and additionally using the recent Faucher–Giguere background ` mostly resolves the PUC, along with producing a flux probability distribution function in accord with observations. The PUC becomes apparent at late epochs (z 1) where the jet and no-jet simulations diverge; at higher redshifts SIMBA reproduces the observed DA with no adjustment, with or without jets. The main impact of jet feedback is to lower the cosmic baryon fraction in the diffuse IGM from 39 per cent to 16 per cent at z = 0, while increasing the warm-hot intergalactic medium (WHIM) baryon fraction from 30 per cent to 70 per cent; the lowering of the diffuse IGM content directly translates into a lowering of DA by a similar factor. Comparing to the older MUFASA simulation that employs different quenching feedback but is otherwise similar to SIMBA, MUFASA matches DA less well than SIMBA, suggesting that low-redshift measurements of DA and H I could provide constraints on feedback mechanisms. Our results suggest that widespread IGM heating at late times is a plausible solution to the PUC, and that SIMBA’s jet active galactic nucleus feedback model, included to quench massive galaxies, approximately yields this required heating.
Mergers, starbursts, and quenching in the SIMBA simulation
(MNRAS, 2019-07-29) Montero, Francisco Rodr´ıguez; Wild, Vivienne; Dave, Romeel
We use the SIMBAcosmological galaxy formation simulation to investigate the relationship between major mergers ( 4:1), starbursts, and galaxy quenching. Mergers are identified via sudden jumps in stellar mass M∗ well above that expected from in situ star formation, while quenching is defined as going from specific star formation rate (sSFR) > t −1 H to < 0.2t −1 H , where tH is the Hubble time. At z ≈ 0–3, mergers show ∼2–3× higher SFR than a massmatched sample of star-forming galaxies, but globally represent 1 per cent of the cosmic SF budget. At low masses, the increase in SFR in mergers is mostly attributed to an increase in the H2 content, but for M∗ 1010.5M mergers also show an elevated star formation efficiency suggesting denser gas within merging galaxies. The merger rate for star-forming galaxies shows a rapid increase with redshift, ∝(1 + z)3.5, but the quenching rate evolves much more slowly, ∝(1 + z)0.9; there are insufficient mergers to explain the quenching rate at z 1.5. SIMBA first quenches galaxies at z 3, with a number density in good agreement with observations. The quenching time-scales τ q are strongly bimodal, with ‘slow’ quenchings (τ q ∼ 0.1tH) dominating overall, but ‘fast’ quenchings (τ q ∼ 0.01tH) dominating in M∗ ∼ 1010– 1010.5M galaxies, likely induced by SIMBA’s jet-mode black hole feedback. The delay time distribution between mergers and quenching events suggests no physical connection to either fast or slow quenching. Hence, SIMBA predicts that major mergers induce starbursts, but are unrelated to quenching in either fast or slow mode.
Mufasa: The assembly of the red sequence
(Oxford University Press, 2017) Dave, Romeel; Rafieferantso, Mika H.; Thompson, Robert J.
We examine the growth and evolution of quenched galaxies in the Mufasa cosmo- logical hydrodynamic simulations that include an evolving halo mass-based quench- ing prescription, with galaxy colours computed accounting for line-of-sight extinc- tion to individual star particles. Mufasa reproduces the observed present-day red sequence quite well, including its slope, amplitude, and scatter. In Mufasa, the red sequence slope is driven entirely by the steep stellar mass{stellar metallicity relation, which independently agrees with observations. High-mass star-forming galaxies blend smoothly onto the red sequence, indicating the lack of a well-de ned green valley at M & 1010:5M . The most massive galaxies quench the earliest and then grow very little in mass via dry merging; they attain their high masses at earlier epochs when cold in ows more e ectively penetrate hot halos. To higher redshifts, the red sequence becomes increasingly contaminated with massive dusty star-forming galaxies; UVJ selection subtly but e ectively separates these populations. We then examine the evo- lution of the mass functions of central and satellite galaxies split into passive and star-forming via UVJ. Massive quenched systems show good agreement with obser- vations out to z 2, despite not including a rapid early quenching mode associated with mergers. However, low-mass quenched galaxies are far too numerous at z . 1 in Mufasa, indicating that Mufasa strongly over-quenches satellites. A challenge for hydrodynamic simulations is to devise a quenching model that produces enough early massive quenched galaxies and keeps them quenched to z = 0, while not being so strong as to over-quench satellites; Mufasa only succeeds at the former.

Browsing by Author "Dave, Romeel"

Results Per Page

Sort Options