scholarly journals Determining the full satellite population of a Milky Way-mass halo in a highly resolved cosmological hydrodynamic simulation

2021 ◽  
Author(s):  
Robert J J Grand ◽  
Federico Marinacci ◽  
Rüdiger Pakmor ◽  
Christine M Simpson ◽  
Ashley J Kelly ◽  
...  
Keyword(s):  
High Resolution ◽  
Galaxy Formation ◽  
Milky Way ◽  
Central Star ◽  
Mass Resolution ◽  
Star Formation History ◽  
Star Forming ◽  
V Band ◽  
Standard Resolution ◽  
Galaxy Population

Abstract We investigate the formation of the satellite galaxy population of a Milky Way-mass halo in a very highly resolved magneto-hydrodynamic cosmological zoom-in simulation (baryonic mass resolution mb = 800 $\rm M_{\odot }$). We show that the properties of the central star-forming galaxy, such as the radial stellar surface density profile and star formation history, are: i) robust to stochastic variations associated with the so-called ‘Butterfly Effect’; and ii) well converged over 3.5 orders of magnitude in mass resolution. We find that there are approximately five times as many satellite galaxies at this high resolution compared to a standard ($m_b\sim 10^{4-5}\, \rm M_{\odot }$) resolution simulation of the same system. This is primarily because 2/3rds of the high resolution satellites do not form at standard resolution. A smaller fraction (1/6th) of the satellites present at high resolution form and disrupt at standard resolution; these objects are preferentially low-mass satellites on intermediate- to low-eccentricity orbits with impact parameters ≲ 30 kpc. As a result, the radial distribution of satellites becomes substantially more centrally concentrated at higher resolution, in better agreement with recent observations of satellites around Milky Way-mass haloes. Finally, we show that our galaxy formation model successfully forms ultra-faint galaxies and reproduces the stellar velocity dispersion, half-light radii, and V-band luminosities of observed Milky Way and Local Group dwarf galaxies across 6 orders of magnitude in luminosity (103-$10^{9}\, \rm L_{\odot }$).

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 The Bimodality of Galaxy Populations Revisited Through Spectral Synthesis

2006 ◽  
Vol 2 (S235) ◽  
pp. 139-139
Author(s):  
L. Sodré ◽  
A. Mateus ◽  
R. Cid Fernandes ◽  
G. Stasińska ◽  
W. Schoenell ◽  
...  
Keyword(s):  
Galaxy Formation ◽  
Spectral Synthesis ◽  
Synthesis Method ◽  
Local Universe ◽  
Massive Galaxies ◽  
Star Forming ◽  
The Galaxy ◽  
Galaxy Populations ◽  
Galaxy Population ◽  
Stellar Masses

AbstractWe revisit the bimodality of the galaxy population seen in the local universe. We address this issue in terms of physical properties of galaxies, such as mean stellar ages and stellar masses, derived from the application of a spectral synthesis method to galaxy spectra from the SDSS. We show that the mean light-weighted stellar age of galaxies presents the best description of the bimodality seen in the galaxy population. The stellar mass has an additional role since most of the star-forming galaxies present in the local universe are low-mass galaxies. Our results give support to the existence of a ‘downsizing’ in galaxy formation, where nowadays massive galaxies tend to have stellar populations older than those found in less massive objects.

scholarly journals The relationship between black hole mass and galaxy properties: examining the black hole feedback model in IllustrisTNG

2020 ◽  
Vol 493 (2) ◽  
pp. 1888-1906 ◽  
Author(s):  
Bryan A Terrazas ◽  
Eric F Bell ◽  
Annalisa Pillepich ◽  
Dylan Nelson ◽  
Rachel S Somerville ◽  
...  
Keyword(s):  
Black Hole ◽  
Star Formation ◽  
Galaxy Formation ◽  
Formation Rate ◽  
Black Hole Mass ◽  
Star Forming ◽  
Stellar Radius ◽  
Accretion Rates ◽  
Hole Model ◽  
Galaxy Population

ABSTRACT Supermassive black hole feedback is thought to be responsible for the lack of star formation, or quiescence, in a significant fraction of galaxies. We explore how observable correlations between the specific star formation rate (sSFR), stellar mass (Mstar), and black hole mass (MBH) are sensitive to the physics of black hole feedback in a galaxy formation model. We use the IllustrisTNG simulation suite, specifically the TNG100 simulation and 10 model variations that alter the parameters of the black hole model. Focusing on central galaxies at z = 0 with Mstar > 1010 M⊙, we find that the sSFR of galaxies in IllustrisTNG decreases once the energy from black hole kinetic winds at low accretion rates becomes larger than the gravitational binding energy of gas within the galaxy stellar radius. This occurs at a particular MBH threshold above which galaxies are found to sharply transition from being mostly star forming to mostly quiescent. As a result of this behaviour, the fraction of quiescent galaxies as a function of Mstar is sensitive to both the normalization of the MBH–Mstar relation and the MBH threshold for quiescence in IllustrisTNG. Finally, we compare these model results to observations of 91 central galaxies with dynamical MBH measurements with the caveat that this sample is not representative of the whole galaxy population. While IllustrisTNG reproduces the observed trend that quiescent galaxies host more massive black holes, the observations exhibit a broader scatter in MBH at a given Mstar and show a smoother decline in sSFR with MBH.

scholarly journals High-Resolution B-Photometry of the Milky Way and Results on Galactic Structure

1990 ◽  
Vol 139 ◽  
pp. 205-206
Author(s):  
S. Kimeswenger ◽  
W. Schlosser ◽  
K. J. Seidensticker ◽  
B. Hoffmann ◽  
Th. Schmidt-Kaler
Keyword(s):  
High Resolution ◽  
Milky Way ◽  
Galactic Structure ◽  
Surface Photometry ◽  
High Resolution Data ◽  
V Band ◽  
The Galaxy ◽  
Global Parameters ◽  
Pioneer 10 ◽  
Resolution Data

During the last two decades, many attempts were made to determine the global parameters of the Galaxy and to compare the Galaxy to other galaxies (Schmidt-Kaler and Schlosser 1973; de Vaucouleurs and Pence 1978; Gilmore 1984; van der Kruit 1986). While most of these investigations are based on star counts, a detailed overall study by surface photometry, because of the lack of homogeneous high-resolution data, is rare. The last attempt by van der Kruit (1986), based on Pioneer 10 data, suffered from low resolution. The great number of individual structures at low and even intermediate latitudes could not be recognized. Our work (B-band, Hoffmann et al. 1989, this volume; V-band, Schlosser, Schmidt-Kaler, and Schneider 1989; U-Band and R-band photometry, in preparation) provides this homogeneous high-resolution data.

scholarly journals The artemis simulations: stellar haloes of Milky Way-mass galaxies

2020 ◽  
Vol 498 (2) ◽  
pp. 1765-1785 ◽  
Author(s):  
Andreea S Font ◽  
Ian G McCarthy ◽  
Robert Poole-Mckenzie ◽  
Sam G Stafford ◽  
Shaun T Brown ◽  
...  
Keyword(s):  
High Resolution ◽  
Galaxy Formation ◽  
Large Scale ◽  
Milky Way ◽  
Mass Density ◽  
Power Laws ◽  
Stellar Feedback ◽  
Radial Profiles ◽  
Hydrodynamical Simulations

ABSTRACT We introduce the Assembly of high-ResoluTion Eagle-simulations of MIlky Way-type galaxieS (artemis) simulations, a new set of 42 zoomed-in, high-resolution (baryon particle mass of $\approx 2\times 10^4 \, {\rm M}_{\odot }\, h^{-1}$), hydrodynamical simulations of galaxies residing in haloes of Milky Way mass, simulated with the eagle galaxy formation code with re-calibrated stellar feedback. In this study, we analyse the structure of stellar haloes, specifically the mass density, surface brightness, metallicity, colour, and age radial profiles, finding generally very good agreement with recent observations of local galaxies. The stellar density profiles are well fitted by broken power laws, with inner slopes of ≈−3, outer slopes of ≈−4, and break radii that are typically ≈20–40 kpc. The break radii generally mark the transition between in situ formation and accretion-driven formation of the halo. The metallicity, colour, and age profiles show mild large-scale gradients, particularly when spherically averaged or viewed along the major axes. Along the minor axes, however, the profiles are nearly flat, in agreement with observations. Overall, the structural properties can be understood by two factors: that in situ stars dominate the inner regions and that they reside in a spatially flattened distribution that is aligned with the disc. Observations targeting both the major and minor axes of galaxies are thus required to obtain a complete picture of stellar haloes.

scholarly journals Chandra and ALMA observations of the nuclear activity in two strongly lensed star-forming galaxies

2018 ◽  
Vol 610 ◽  
pp. A53 ◽  
Author(s):  
M. Massardi ◽  
A. F. M. Enia ◽  
M. Negrello ◽  
C. Mancuso ◽  
A. Lapi ◽  
...  
Keyword(s):  
Star Formation ◽  
High Resolution ◽  
Galaxy Formation ◽  
High Redshift ◽  
Energy Budgets ◽  
Spectral Energy ◽  
Nuclear Activity ◽  
X Ray ◽  
Star Forming ◽  
Early Stages

Aim. According to coevolutionary scenarios, nuclear activity and star formation play relevant roles in the early stages of galaxy formation. We aim at identifying them in high-redshift galaxies by exploiting high-resolution and high-sensitivity X-ray and millimeter-wavelength data to confirm the presence or absence of star formation and nuclear activity and describe their relative roles in shaping the spectral energy distributions and in contributing to the energy budgets of the galaxies. Methods. We present the data, model, and analysis in the X-ray and millimeter (mm) bands for two strongly lensed galaxies, SDP.9 (HATLAS J090740.0-004200) and SDP.11 (HATLAS J091043.1-000322), which we selected in the Herschel-ATLAS catalogs for their excess emission in the mid-IR regime at redshift ≳1.5. This emission suggests nuclear activity in the early stages of galaxy formation. We observed both of them with Chandra ACIS-S in the X-ray regime and analyzed the high-resolution mm data that are available in the ALMA Science Archive for SDP.9. By combining the information available in mm, optical, and X-ray bands, we reconstructed the source morphology. Results. Both targets were detected in the X-ray, which strongly indicates highly obscured nuclear activity. ALMA observations for SDP.9 for the continuum and CO(6-5) spectral line with high resolution (0.02 arcsec corresponding to ~65 pc at the distance of the galaxy) allowed us to estimate the lensed galaxy redshift to a better accuracy than pre-ALMA estimates (1.5753 ± 0.0003) and to model the emission of the optical, millimetric, and X-ray band for this galaxy. We demonstrate that the X-ray emission is generated in the nuclear environment, which strongly supports that this object has nuclear activity. On the basis of the X-ray data, we attempt an estimate of the black hole properties in these galaxies. Conclusions. By taking advantage of the lensing magnification, we identify weak nuclear activity associated with high-z galaxies with high star formation rates. This is useful to extend the investigation of the relationship between star formation and nuclear activity to two intrinsically less luminous high-z star-forming galaxies than was possible so far. Given our results for only two objects, they alone cannot constrain the evolutionary models, but provide us with interesting hints and set an observational path toward addressing the role of star formation and nuclear activity in forming galaxies.

scholarly journals Extensive Lensing Survey of Optical and Near-infrared Dark Objects (El Sonido): HST H-faint Galaxies behind 101 Lensing Clusters

2021 ◽  
Vol 922 (2) ◽  
pp. 114
Author(s):  
Fengwu Sun ◽  
Eiichi Egami ◽  
Pablo G. Pérez-González ◽  
Ian Smail ◽  
Karina I. Caputi ◽  
...  
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
Near Infrared ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Mass Range ◽  
Star Forming ◽  
Photometric Redshift ◽  
Galaxy Population ◽  
Massive Galaxy

Abstract We present a Spitzer/IRAC survey of H-faint (H 160 ≳ 26.4, < 5σ) sources in 101 lensing cluster fields. Across a CANDELS/Wide-like survey area of ∼648 arcmin2 (effectively ∼221 arcmin2 in the source plane), we have securely discovered 53 sources in the IRAC Channel-2 band (CH2, 4.5 μm; median CH2 = 22.46 ± 0.11 AB mag) that lack robust HST/WFC3-IR F160W counterparts. The most remarkable source in our sample, namely ES-009 in the field of Abell 2813, is the brightest H-faint galaxy at 4.5 μm known so far (CH2 = 20.48 ± 0.03 AB mag). We show that the H-faint sources in our sample are massive (median M star = 1010.3±0.3 M ⊙), star-forming (median star formation rate = 100 − 40 + 60 M ⊙ yr−1), and dust-obscured (A V = 2.6 ± 0.3) galaxies around a median photometric redshift of z = 3.9 ± 0.4. The stellar continua of 14 H-faint galaxies can be resolved in the CH2 band, suggesting a median circularized effective radius (R e,circ; lensing corrected) of 1.9 ± 0.2 kpc and <1.5 kpc for the resolved and whole samples, respectively. This is consistent with the sizes of massive unobscured galaxies at z ∼ 4, indicating that H-faint galaxies represent the dusty tail of the distribution of a wider galaxy population. Comparing with the ALMA dust continuum sizes of similar galaxies reported previously, we conclude that the heavy dust obscuration in H-faint galaxies is related to the compactness of both stellar and dust continua (R e,circ ∼ 1 kpc). These H-faint galaxies make up 16 − 7 + 13 % of the galaxies in the stellar-mass range of 1010 − 1011.2 M ⊙ at z = 3 ∼ 5, contributing to 8 − 4 + 8 % of the cosmic star formation rate density in this epoch and likely tracing the early phase of massive galaxy formation.

scholarly journals The Controversial Star-Formation History and Helium Enrichment of the Milky Way Bulge

2016 ◽  
Vol 33 ◽  
Author(s):  
David M. Nataf
Keyword(s):  
Star Formation ◽  
Main Sequence ◽  
Milky Way ◽  
Central Star ◽  
Asymptotic Giant Branch ◽  
Star Formation History ◽  
Asymptotic Giant Branch Stars ◽  
Rr Lyrae ◽  
Formation History ◽  
Solar Metallicity

AbstractThe stellar population of the Milky Way bulge is thoroughly studied, with a plethora of measurements from virtually the full suite of instruments available to astronomers. It is thus perhaps surprising that alongside well-established results lies some substantial uncertainty in its star-formation history. Cosmological models predict the bulge to host the Galaxy's oldest stars for [Fe/H] ≲ −1, and this is demonstrated by RR Lyrae stars and globular cluster observations. There is consensus that bulge stars with [Fe/H] ≲ 0 are older than t ≈ 10 Gyr. However, at super-solar metallicity, there is a substantial unresolved discrepancy. Data from spectroscopic measurements of the main-sequence turnoff and subgiant branch, the abundances of asymptotic giant branch stars, the period distribution of Mira variables, the chemistry and central-star masses of planetary nebulae, all suggest a substantial intermediate-age population (t ≈ 3 Gyr). This is in conflict with predictions from cosmologically motivated chemical evolution models and photometric studies of the main-sequence turnoff region, which both suggest virtually no stars younger than t ≈ 8 Gyr. A possible resolution to this conflict is enhanced helium-enrichment, as this would shift nearly all of the age estimates in the direction of decreasing discrepancy.

scholarly journals High–Resolution V–Band Photometry of the Milky Way

1990 ◽  
Vol 139 ◽  
pp. 203-204
Author(s):  
B. Hoffmann ◽  
S. Kimeswenger ◽  
W. Schlosser ◽  
Th. Schmidt-Kaler ◽  
K. J. Seidensticker
Keyword(s):  
High Resolution ◽  
Milky Way ◽  
Brightness Distribution ◽  
Mean Deviation ◽  
Spherical Mirror ◽  
Image Size ◽  
V Band ◽  
Scan Time ◽  
The Mean ◽  
Wide Angle Camera

High resolution (0.°25 × 0.°25) surface brightness distribution in V of the southern Milky Way over an area of 200° ≤ l ≤ 60° and of −30° ≤ b ≤ +30° was obtained by photographic plates, taken at La Silla, Chile, with the super-wide-angle camera with spherical mirror of the Astronomisches Institut der Ruhr-Universität Bochum (Schmidt-Kaler et al. 1983). Schmidt-Kaler et al. (1983) and Seidensticker, Schmidt-Kaler, and Schlosser (1982) carried out an analysis of these plates. However, these studies used only a fraction of the whole plate; interesting parts of the sky were chosen near the plate centers, thus minimizing various errors. The plates are now all scanned over the whole field of view with a PDS with a diaphragm of 50 × 50 μm = 0.°12 × 0.° 12 on the sky. The image size is 1201 × 1201 pixels per plate. The mean deviation during the scan time was less than 0.1%. Through the identification of about 50 stars and by using their l, b and x, y coordinates, the equations of the plates were solved with eight geometric parameters. The standard deviation of all parameters was less than 0.3 pixels on all plates.

scholarly journals Cosmological simulations of the same spiral galaxy: the impact of baryonic physics

2020 ◽  
Vol 501 (1) ◽  
pp. 62-77
Author(s):  
A Nuñez-Castiñeyra ◽  
E Nezri ◽  
J Devriendt ◽  
R Teyssier
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Galaxy Formation ◽  
Spiral Galaxy ◽  
Milky Way ◽  
Spiral Galaxies ◽  
Cosmological Simulations ◽  
Star Forming ◽  
Small Scales ◽  
The Impact

ABSTRACT The interplay of star formation (SF) and supernova (SN) feedback in galaxy formation is a key element for understanding galaxy evolution. Since these processes occur at small scales, it is necessary to have sub-grid models that recover their evolution and environmental effects at the scales reached by cosmological simulations. In this work, we present the results of the Mochima simulation, where we simulate the same spiral galaxy inhabiting a Milky Way (MW) size halo in a cosmological environment changing the sub-grid models for SN feedback and SF. We test combinations of the Schmidt law and a multifreefall based SF with delayed cooling feedback or mechanical feedback. We reach a resolution of 35 pc in a zoom-in box of 36 Mpc. For this, we use the code $\rm{\small RAMSES}$ with the implementation of gas turbulence in time and trace the local hydrodynamical features of the star-forming gas. Finally, we compare the galaxies at redshift 0 with global and interstellar medium observations in the MW and local spiral galaxies. The simulations show successful comparisons with observations. Nevertheless, diverse galactic morphologies are obtained from different numerical implementations. We highlight the importance of detailed modelling of the SF and feedback processes, especially for simulations with a resolution that start to reach scales relevant for molecular cloud physics. Future improvements could alleviate the degeneracies exhibited in our simulated galaxies under different sub-grid models.

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