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ZOMG: Does the halo assembly history influence central galaxies and - PowerPoint PPT Presentation

Jun 19, 2023 •441 likes •668 views

ZOMG: Does the halo assembly history influence central galaxies and gas accretion? Emilio Romano-Diaz Enrico Garaldi Mikolaj Borzyszkowski Cristiano Porciani Malta The role of gas in galaxy dynamics October 2 - 6 1 Halo assembly bias 2pt

  1. ZOMG: Does the halo assembly history influence central galaxies and gas accretion? Emilio Romano-Diaz Enrico Garaldi Mikolaj Borzyszkowski Cristiano Porciani Malta The role of gas in galaxy dynamics October 2 - 6 1

  2. Halo assembly bias 2pt correlation function —> halo clustering • Nbody simulations have shown that the clustering of halos of fixed mass varies with halo formation time, concentration and substructure occupation (Sheth & Tormen 04; Gao +05; Gao & White 07; Jing +07; Harker +06; Wechsler +06; Wetzel +07…) • Old haloes reside in dense environments, younger ones in less dense regions. • This e ff ect is stronger at lower masses and absent at high masses (Gao, Springel & White 05)

  3. Does the presence of halo assembly bias implies whether also “ galaxy assembly bias ” exists? In other words, to what extent the assembly history of the host haloes influences galaxy properties and imprints detectable signatures in the galaxy-clustering pattern? (e.g. Jung, Lee & Yi 2014; Hearin, Watson & van den Bosch 2015; Hearin et al. 2016; Lin et al. 2016, Henriques et al. 2015) Does the gas follows the same behaviour as DM during accretion? ZOMG project

  4. 
 ZOMG Project: 
 Z ooming On a Mob of Galaxies 1. Dark Matter Haloes, assembly bias: Borzyszkowski et al. 2017 2. Galaxy formation, gas accretion: Romano-Diaz et al. 2017 3. Substructure evolution: Garaldi et al. 2017 4. …

  5. ZOMG Project: 
 Z ooming On a Mob of Galaxies (Oxford living Dictionary)

  6. ZOMG! Simulations • GADGET3, Zoom-in simulations, Planck Cosmology, • 7 haloes (DM-only) hosting present-day L * galaxies, M h ~5x10 11 M ☉ (Borzyszkowski+17) I. Sampling rate 20Myr => detailed assembly history II. 2 haloes collapsed z ~ 0 (accreting) III. 5 haloes collapsed z ~ 1.5 (stalled)

  7. ZOMG! Simulations • GADGET3, Zoom-in simulations, Planck Cosmology, • 7 haloes (DM-only) hosting present-day L * galaxies, M h ~5x10 11 M ☉ (Borzyszkowski+17) I. Sampling rate 20Myr => detailed assembly history II. 2 haloes collapsed z ~ 0 ( accreting ) III. 5 haloes collapsed z ~ 1.5 ( stalled ) (Borzyszkowski+17)

  8. ZOMG! Simulations • GADGET3, Zoom-in simulations, Planck Cosmology, • 7 haloes (DM-only) hosting present-day L * galaxies, M h ~5x10 11 M ☉ (Borzyszkowski+17) I. Sampling rate 20Myr => detailed assembly history II. 2 haloes collapsed z ~ 0 ( accreting ) III. 5 haloes collapsed z ~ 1.5 ( stalled ) Introduces strong assembly bias! Resolution independent! (Borzyszkowski+17)

  9. ZOMG! Simulations • GADGET3, Zoom-in simulations, Planck Cosmology, Accreting Stalled • 7 haloes (DM-only) hosting present-day L * galaxies, M h ~5x10 11 M ☉ (Borzyszkowski+17) Embedded in filaments! Nodes! I. Sampling rate 20Myr => detailed assembly history II. 2 haloes collapsed z ~ 0 ( accreting ) III. 5 haloes collapsed z ~ 1.5 ( stalled ) Introduces strong assembly bias! Resolution independent! (Borzyszkowski+17)

  10. ZOMG!! Simulations • GADGET3, Zoom-in simulations, Planck Cosmology. I. 4 haloes: 2 stalled + 2 accreting II. DM + Hydro (UV, SNe, Winds, SF , cooling), M * = 10 4 M ☉ ε =200pc III. M star ~ 2-3X10 10 M ☉ , M gas ~ 10 10 M ☉ Moster+13 
 Behroozi+13 (Romano-Diaz+17)

  11. ZOMG!! Simulations • GADGET3, Zoom-in simulations, Planck Stalled Cosmology. ZOh My Gods!! Accreting I. 4 haloes: 2 stalled + 2 accreting II. DM + Hydro (UV, SNe, Winds, SF , cooling), M * = 10 4 M ☉ ε =200pc III. M star ~ 2-3X10 10 M ☉ , M gas ~ 10 10 M ☉ Moster+13 
 Behroozi+13 (Romano-Diaz+17)

  12. ZOMG!! Simulations Stellar discs ( 𝜏 v ) Gaseous discs (Z) (Romano-Diaz+17)

  13. ZOMG!! Simulations Stellar discs ( 𝜏 v ) ] 8.0 5.0 3.0 2.0 1.0 0.5 0.0 6 SFR peaks close to halo formation time 
 6uSay for S-haloes 6iris 5 Amun Abu 4 6F5 [0 ⊙ yr − 1 ] Gaseous discs (Z) 3 2 1 0 0 2 4 6 8 10 12 SFR Time [Gyr] (Romano-Diaz+17)

  14. Galaxy properties NO correlation with halo formation time! Decent agreement wrt observations, Discs galaxies Vertical profiles S-galaxies have thicker discs! (secular evolution) (Villalobos & Helmi 08, Bournaud+09)

  15. Circularity j z (Abadi+03) ✏ ∗ = j circ • S-galaxies have thicker discs • age disc coincides with SF-peak • Older discs for S-gals. • bulges are older

  16. Accretion halo growth ~ 10-20% 2 decrease 1.5 Substructures Outer regions r 100 Inflows ~ outflows Inner regions: r 20 Analysis being done from formation halo time (S) or time of last major merger (A)

  17. Infall DM Accretion Matter confined (inner) regions, rapid increase 
 S - saturates z~0.6 A - increases z=0. Infall rates A > S Only 50% goes 
 from r 100 -> r 20 Gas Recycled decreases 
 at inner regions (SF) 
 constant at large-r Recycled ~ Newly accreted @ z~0 Accretion at high-z 
 @ high-z new ~ 10X recycled ~10M ☉ /yr -> 2M ☉ /yr 
 A ~ 2xS (z~0)

  18. ZOMG!!! 
 Satellites Satellite dynamics reflect the type of halo they belong to Satellites at accretion: 
 A -accreted on to their hosts in nearly radial orbits, 
 isotropic pattern S -have a more prominent tangential component, first into filament, then onto main halo Garaldi +07

  19. Garaldi +17 Satellites β = 1 − Σ v 2 t 2 Σ v 2 r 10 Classical 
 MW satellites Milky Way satellites show a prominent excess of tangential orbits which is quite unusual within the CDM paradigm (Cautun & Frenk 16) Stalled haloes show consistently - β => MW’s DM halo is stalled (?) Di ff erent selections criteria in ZOMG

  20. Conclusions • Assembly bias originates by the environment of the halo 1. Stalled haloes: embedded in filaments, stop growing z>1, more relaxed 2. Accreting haloes: located at nodes, radial infall/orbits, not fully relaxed • DM is acquired via smooth & satellite accretion, no net mass accretion @r 20 , inflow = outflow @r 300 • Gas mimics the DM accretion patter at the halo outskirts • Clear distinction in central regions (r 20 ), S-haloes consistently acquire less fresh gas than their A-counterparts. [even @ r 100 ] • Due to long cooling times, gas accretion at the centre does not necessarily reflect what happens in the outskirts of the halo • No correlation between assembly halo time and galaxy morphology ( => implications for Halo-matching like models ? ) • Most properties of the main galaxies are insensitive to this bias, with the exception of: ( => implications for Halo abundance- matching like models ? ) A. The median stellar age of the disc component clearly reflects the halo assembly time. In S-galaxies disc started to be assembled by z~2 (older). This process is delayed until z < 1 in the accreting haloes. B. Thickness of the disc shows a clear distinction: S-galaxies are thicker by a factor of two than their A-counterparts. • ShMF , radial distributions, stellar mass fractions & velocity dispersions are insensitive to the halo collapse time. • @z=0 the velocity anisotropy parameter of satellites is >0 for A-haloes and <0 for S-haloes. The tangential excess as measured from classical MW satellites is ~ -2.2

  21. Conclusions • Assembly bias originates by the environment of the halo 1. Stalled haloes: embedded in filaments, stop growing z>1, more relaxed 2. Accreting haloes: located at nodes, radial infall/orbits, not fully relaxed • DM is acquired via smooth & satellite accretion, no net mass accretion @r 20 , inflow = outflow @r 300 • Gas mimics the DM accretion patter at the halo outskirts • Clear distinction in central regions (r 20 ), S-haloes consistently acquire less fresh gas than their A-counterparts. [even @ r 100 ] Considering all these evidence, it is thus tempting to • Due to long cooling times, gas accretion at the centre does not necessarily reflect what happens in the outskirts of the halo tentatively categorise the MW halo as stalled • No correlation between assembly halo time and galaxy morphology ( => implications for Halo-matching like models ? ) • Most properties of the main galaxies are insensitive to this bias, with the exception of: ( => implications for Halo abundance- matching like models ? ) A. The median stellar age of the disc component clearly reflects the halo assembly time. In S-galaxies disc started to be assembled by z~2 (older). This process is delayed until z < 1 in the accreting haloes. B. Thickness of the disc shows a clear distinction: S-galaxies are thicker by a factor of two than their A-counterparts. • ShMF , radial distributions, stellar mass fractions & velocity dispersions are insensitive to the halo collapse time. • @z=0 the velocity anisotropy parameter of satellites is >0 for A-haloes and <0 for S-haloes. The tangential excess as measured from classical MW satellites is ~ -2.2

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