scholarly journals Abundance matching with the mean star formation rate: there is no missing satellites problem in the Milky Way above M200 ∼ 109 M⊙

2019 ◽  
Vol 487 (4) ◽  
pp. 5799-5812 ◽  
Author(s):  
J I Read ◽  
D Erkal
Keyword(s):  
Star Formation ◽  
Cold Dark Matter ◽  
Milky Way ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Mass Function ◽  
Accurate Estimate ◽  
Empirical Method ◽  
Galactic Centre ◽  
The Mean

ABSTRACT We introduce a novel abundance matching technique that produces a more accurate estimate of the pre-infall halo mass, M200, for satellite galaxies. To achieve this, we abundance match with the mean star formation rate, averaged over the time when a galaxy was forming stars, 〈SFR〉, instead of the stellar mass, M∗. Using data from the Sloan Digital Sky Survey, the GAMA survey and the Bolshoi simulation, we obtain a statistical 〈SFR〉−M200 relation in Λ cold dark matter. We then compare the pre-infall halo mass, $M^{\rm abund}_{200}$, derived from this relation with the pre-infall dynamical mass, $M^{\rm dyn}_{200}$, for 21 nearby dSph and dIrr galaxies, finding a good agreement between the two. As a first application, we use our new 〈SFR〉−M200 relation to empirically measure the cumulative mass function of a volume-complete sample of bright Milky Way satellites within 280 kpc of the Galactic centre. Comparing this with a suite of cosmological ‘zoom’ simulations of Milky Way-mass haloes that account for subhalo depletion by the Milky Way disc, we find no missing satellites problem above M200 ∼ 109 M⊙ in the Milky Way. We discuss how this empirical method can be applied to a larger sample of nearby spiral galaxies.

scholarly journals The link between solenoidal turbulence and slow star formation in G0.253+0.016

2016 ◽  
Vol 11 (S322) ◽  
pp. 123-128 ◽  
Author(s):  
C. Federrath ◽  
J. M. Rathborne ◽  
S. N. Longmore ◽  
J. M. D. Kruijssen ◽  
J. Bally ◽  
...  
Keyword(s):  
Star Formation ◽  
Mach Number ◽  
Milky Way ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Dust Emission ◽  
Volume Density ◽  
Galactic Centre ◽  
Galactic Disc ◽  
Density Variance

AbstractStar formation in the Galactic disc is primarily controlled by gravity, turbulence, and magnetic fields. It is not clear that this also applies to star formation near the Galactic Centre. Here we determine the turbulence and star formation in the CMZ cloud G0.253+0.016. Using maps of 3 mm dust emission and HNCO intensity-weighted velocity obtained with ALMA, we measure the volume-density variance σρ /ρ 0=1.3±0.5 and turbulent Mach number $\mathcal{M}$ = 11±3. Combining these with turbulence simulations to constrain the plasma β = 0.34±0.35, we reconstruct the turbulence driving parameter b=0.22±0.12 in G0.253+0.016. This low value of b indicates solenoidal (divergence-free) driving of the turbulence in G0.253+0.016. By contrast, typical clouds in the Milky Way disc and spiral arms have a significant compressive (curl-free) driving component (b > 0.4). We speculate that shear causes the solenoidal driving in G0.253+0.016 and show that this may reduce the star formation rate by a factor of 7 compared to nearby clouds.

scholarly journals From the outside looking in: what can Milky Way analogues tell us about the star formation rate of our own galaxy?

2019 ◽  
Vol 489 (4) ◽  
pp. 5030-5036 ◽  
Author(s):  
Amelia Fraser-McKelvie ◽  
Michael Merrifield ◽  
Alfonso Aragón-Salamanca
Keyword(s):  
Star Formation ◽  
Standard Deviation ◽  
Milky Way ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Structural Features ◽  
Mid Infrared ◽  
Recent Estimate ◽  
The Mean

ABSTRACT The Milky Way has been described as an anaemic spiral, but is its star formation rate (SFR) unusually low when compared to its peers? To answer this question, we define a sample of Milky Way analogues (MWAs) based on stringent cuts on the best literature estimates of non-transient structural features for the Milky Way. This selection yields only 176 galaxies from the whole of the SDSS DR7 spectroscopic sample which have morphological classifications in Galaxy Zoo 2, from which we infer SFRs from two separate indicators. The mean SFRs found are $\log (\rm {SFR}_{SED}/\rm {M}_{\odot }~\rm {yr}^{-1})=0.53$ with a standard deviation of 0.23 dex from SED fits, and $\log (\rm {SFR}_{W4}/\rm {M}_{\odot }~\rm {yr}^{-1})=0.68$ with a standard deviation of 0.41 dex from a mid-infrared calibration. The most recent estimate for the Milky Way’s SFR of $\log (\rm {SFR}_{MW}/\rm {M}_{\odot }~\rm {yr}^{-1})=0.22$ fits well within 2$\sigma$ of these values, where $\sigma$ is the standard deviation of each of the SFR indicator distributions. We infer that the Milky Way, while being a galaxy with a somewhat low SFR, is not unusual when compared to similar galaxies.

scholarly journals One Hundred 30 Dors?

2007 ◽  
Vol 3 (S250) ◽  
pp. 307-312 ◽  
Author(s):  
M. M. Hanson ◽  
B. Popescu
Keyword(s):  
Star Formation ◽  
Milky Way ◽  
Star Formation Rate ◽  
Open Cluster ◽  
Formation Rate ◽  
Mass Function ◽  
Open Clusters ◽  
The Galaxy ◽  
Massive Clusters ◽  
Image Simulations

AbstractThere are a few ways to estimate the number of massive open clusters expected in the disk of the Milky Way, such as the total star formation rate of the Galaxy, or the open cluster mass function extrapolated to include the entire Galaxy. Surprisingly, they give similar predictions: the Milky Way should contain about 100 clusters as massive as 30 Doradus. Are we seeing them? We look closely at these predictions and compare them to what has been found so far in our Galaxy. We present sophisticated image simulations our group is developing to estimate the selection biases faced by current infrared searches for these massive clusters.

scholarly journals Legacy of star formation in the pre-reionization universe

2019 ◽  
Vol 488 (2) ◽  
pp. 2202-2221 ◽  
Author(s):  
Jason Jaacks ◽  
Steven L Finkelstein ◽  
Volker Bromm
Keyword(s):  
Star Formation ◽  
Luminosity Function ◽  
Star Formation Rate ◽  
Direct Detection ◽  
Formation Rate ◽  
Mass Function ◽  
James Webb Space Telescope ◽  
Current Limiting ◽  
Molecular Cooling ◽  
Low Mass

ABSTRACT We utilize gizmo, coupled with newly developed sub-grid models for Population III (Pop III) and Population II (Pop II), to study the legacy of star formation in the pre-reionization Universe. We find that the Pop II star formation rate density (SFRD), produced in our simulation (${\sim } 10^{-2}\ \mathrm{M}_\odot \, {\rm yr^{-1}\, Mpc^{-3}}$ at z ≃ 10), matches the total SFRD inferred from observations within a factor of <2 at 7 ≲ z ≲ 10. The Pop III SFRD, however, reaches a plateau at ${\sim }10^{-3}\ \mathrm{M}_\odot \, {\rm yr^{-1}\, Mpc^{-3}}$ by z ≈ 10, remaining largely unaffected by the presence of Pop II feedback. At z  = 7.5, ${\sim } 20{{\ \rm per\ cent}}$ of Pop III star formation occurs in isolated haloes that have never experienced any Pop II star formation (i.e. primordial haloes). We predict that Pop III-only galaxies exist at magnitudes MUV ≳ −11, beyond the limits for direct detection with the James Webb Space Telescope. We assess that our stellar mass function (SMF) and UV luminosity function (UVLF) agree well with the observed low mass/faint-end behaviour at z = 8 and 10. However, beyond the current limiting magnitudes, we find that both our SMF and UVLF demonstrate a deviation/turnover from the expected power-law slope (MUV,turn = −13.4 ± 1.1 at z  = 10). This could impact observational estimates of the true SFRD by a factor of 2(10) when integrating to MUV = −12 (−8) at z ∼ 10, depending on integration limits. Our turnover correlates well with the transition from dark matter haloes dominated by molecular cooling to those dominated by atomic cooling, for a mass Mhalo ≈ 108 M⊙ at z ≃ 10.

scholarly journals THE ADF AND THE t2 FORMALISM IN H II REGIONS BASED ON THE UPPER MASS LIMIT OF THE IMF FOR THE MW

2020 ◽  
Vol 56 (2) ◽  
pp. 235-244
Author(s):  
L. Carigi ◽  
A. Peimbert ◽  
M. Peimbert ◽  
G. Delgado-Inglada
Keyword(s):  
Milky Way ◽  
Spiral Galaxies ◽  
Star Formation Rate ◽  
Direct Method ◽  
Formation Rate ◽  
Mass Function ◽  
Initial Mass Function ◽  
H Ii Regions ◽  
Mass Limit ◽  
Better Than

We study in depth the abundance discrepancy problem in H II regions, this time from a different perspective than the usual one: by studying the effect of the upper mass limit (Mup) of the initial mass function (IMF) on the O, C, and He predicted by chemical evolution models for the Milky Way. We use abundances determined with the direct method (DM) and with the temperature independent method (TIM). We compare the predicted abundances at the present time with observations of Orion, M17, and M8 to determine the Mup value of the galactic IMF. From the DM abundances, the models predict an Mup = 25 − 45 M⨀, while from the TIM, CEMs derive an Mup = 70 − 110 M⨀. Spiral galaxies with the stellar mass and star formation rate of the MW are predicted to have an Mup ≈ 100 M⨀. These results support that abundances derived from the TIM are better than those derived from the DM.

scholarly journals Star Formation of Star Clusters in the SMC and their Adjoining Fields

1986 ◽  
Vol 116 ◽  
pp. 101-102
Author(s):  
M. Kontizas ◽  
E. Kontizas
Keyword(s):  
Star Formation ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Star Clusters ◽  
Mass Function ◽  
Spectroscopic Studies ◽  
Initial Mass Function ◽  
The West ◽  
West Side ◽  
Halo Population

Photometric and recent spectroscopic studies of the SMC have shown that the differences observed in the SMC clusters and those of our Galaxy could be attibuted to differences in metallicity, star formation rate and/or the Initial Mass Function (IMF) (Humphries, 1983). The studied clusters NGC152 and KRON3 are located at the west side of the bar of the SMC and their adjoining fields represent the halo population of this galaxy.

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