Plenary Talk - Malta October 2017 #MaltaGiG Joss Bland-Hawthorn - - PowerPoint PPT Presentation

Plenary Talk - Malta

October 2017 #MaltaGiG

Joss Bland-Hawthorn

ASTRO3D Centre of Excellence SIfA, University of Sydney

u Lessons learned in this decade from the near field

u Gas accre:on onto L* galaxies

#MaltaGiG

Stellar Mass & Baryon TF on same scaling rela:on for stars + gas

Kassin+ 2007

SAMI survey: Cortese+ 2014, 1016 – large homogeneous IFS samples

u One or two dominant spirals per group is the norm locally.

There’s nothing unusual about the Local Group, but it is a quiescent region within Lanikea. Kourkchi & Tully 2017 M ≥ 1012 M virial radius decoupling E = 0

Corollary: binarity of L* galaxies (Sharma+ 2005, 2012)

Who needs stellar bulges ?

Don’t we expect merger-built bulges in CDM? They don’t seem important within 8 Mpc of the

• LG. Few classical bulges in L* galaxies, but we’re

in a quiescent region on supergalac^c scales. (2010)

Pichon 2017

We need a more nuanced understanding of environment. Our es^mators are based on sta^s^cal crowding. This may mean matching our best simula^ons with the best near field observa^ons. Going back to Kormendy’s claim, bulges are not essen:al elements of disk forma:on.

But old, red, thick disks appear to be the norm

Yoachim & Dalcanton 2006 The Galaxy Bensby+ 2014 Do thick disks relate to high-z turbulent disks ?

Galaxy gas disks, like many stellar disks, keep on going, and do not always truncate

NGC 3198 Maloney 1993 Kalberla & Dedes 2008

M31-M33 HI bridge

Wolfe+16 Braun & Thilker 2004

NGC 2997

Maloney 1993

“In search of cool flow accre^on onto galaxies – where does the gas disk end?” JBH et al 2017, 1709.08733

High cosmic UV background

Putman+ 98 Besla+ 10

Gas inflows are hard to observe, but unequivocal in the nearest L* galaxies with HVCs, HI streams

Deep observa^ons reveal 4x more cool to warm gas (Putman+ 12, Fox+ 14), s^ll not enough to sustain SFR today. We rarely, if ever, see Dekel-like cold streams that hit the disk. The gas breaks down high in the halo (d’Onghia & Fox 16).

NGC 891: prior inflow that has already cooled ?

HI: <0.3 M yr-1 (Oosterloo+ 2007) X-rays: <0.4 M yr-1 (Hodges-Kluck+ 2016) EUV: <0.1 M yr-1 (Miller+ 2000) Som X-ray emissivity today too low to explain 30 kpc HI feature ~ 2x107 M

Large-scale wind in the Galaxy: “Galaxy scale ouplows (>1056 erg) may be much more

common than inferred so far, just difficult to detect.”

X: JBH & Cohen 2003 γ: Su et al 2010 UV: Fox et al 2015 HI: Lockman & NMG 2016

The biggest surprises are coming from the hot halo ?

Hot halos are now detected in massive spirals

Li et al 2016 Anderson & Bregman 2011, 2015 Gas accre:on rate < 0.4 M¤ yr-1 in most massive systems (Vrot~ 400 km s-1), not enough to supply SFR

The CGM and lower hot halo are complex regions, difficult to observe and to model

EAGLE (Schaye+ 15) Tumlinson, Peeples, Werk (2017) Most of the gas accre:on is sub-virial ? Does not explain OVIII.

Extraordinary claims on hidden baryonic mass

The hot, metal rich halo dominates the baryon mass in the Galaxy. If this is true, accre^on from inefficiently cooling, hot halo may be viable for building disks since plenty of mass over a Hubble ^me. But what about J ?

Bertone+ 2013, same story with cosmic ^me

Extraordinary claims on hidden ang. momentum

Theory: TTT ensures DM and gas have iden^cal AMD in virialized systems (Fall & Efstathiou 1980). Gas conserves j = J/M during cooling (Mestel 1963). CDM simula:ons (above): Self-similar spin distribu^on for DM and cooling hot gas, no feedback (van den Bosch+ 2002). RECAP

Rd α λRvir

Extraordinary claims on hidden ang. momentum

Using different approaches, Pezzulli, Fraternali & Binney (2017), Tepper-Garcia & JBH (2017) find fast, hot, stable halos are very difficult to

• construct. Something has to give.

This unexpected value implies λ ≈ 0.25 Pezzulli+ 2017

Self-similar spin distribu:on broken in presence of feedback – SN in low mass galaxies, AGN in high mass galaxies (Zjupa & Springel 2017). <λ> ~ 0.08 averaged over all baryons for L* galaxies. Zjupa & Springel are unsure how the gas acquires the spin – mergers, gas/DM interac^on? – in the Illustris simula^ons.

<1011 M¤ >1012 M¤ 1011-12 M¤

How to build an arbitrarily high resolu^on, mul^-phase Galaxy

CDM simula^ons are properly mo^vated but far too grainy. The constructed Galaxy can be used to study how gas breaks down in a fully MHD environment with a Galac^c magne^c field (A. Grønnow, PhD)

λ=0.08 RAMSES (Tepper-Garcia) Galactic parameters (ARAA 54) Zhot= 0.3 Z Static or live halo, constant mass Note hot halo non-spherical

13.0 14.0 15.0 16.0 17.0 18.0 19.0 20.0 21.0 22.0 23.0 10 20 30 40 50 60 70 80 surface density [cm-2] R (kpc) AMR true (exp[-R/Rd]; Rd = 7 kpc) Kalberla & Dedes (2008)

RAMSES Milky Way model. Consider a DM halo filled with Tvir~106 K gas with prescribed amount of J. Allow gas to cool and conserve J/M over Hubble time. Rotationally supported disk with correct mass forms inside-out, scalelength set by spin. We never observe the correct EUVX emissivity to explain baryon disk.

Tepper-Garcia & JBH 2017

λ=0.08

did not evolve long enough

Standard λ=0.04 in CDM halos, i.e. 30 km s-1 hot halo gas. λ=0.08 is consistent with Galactic HI, both Rd and total extent. By construction, impose hot halo spin at start, no SF/AGN feedback

λ=0.08 seems ~consistent with the Galaxy’s disk baryon content

Tepper-Garcia & JBH 2017 λ > 0.12 starts to break down

10% too low Faerman needs to raise curve by 0.6 dex

Coherent accre^on paradigm

Wher Where does a galaxy’ e does a galaxy’s spin come fr s spin come from ?

• m ?

Spin-up fr Spin-up from local tidal tor

• m local tidal torques

ques ≤1 Mpc scale

Grey shows domain of Q

Tidal torque theory (Hoyle 1953)

Spin-up fr Spin-up from long-range tidal for

• m long-range tidal forces in filaments

ces in filaments

Local Group lives along one such filament extending to Virgo

This filament extending to a rich This filament extending to a rich gr group is clear

• up is clearer in velocity space

er in velocity space

Euler (fixed) vs Lagrange (co-moving) frame Three flow axes can project to rotation in the co-moving frame, an effect which is amplified by gravity. Thus, the size of the (low order) vorticity is roughly the Hubble Flow

• parameter. The effect increases with cosmic time.

But vorticity is carried down to smaller scales…

Codis+12,15; Dubois+14; Laigle+15; Chisari+16

Critical mass where it switches over decreases with redshift (~1012 M today) More gas supply at higher z, but more vortex action today, delayed accretion.

LSS connection goes back to: Katz+03; Birnboim & Dekel 03; Keres+05; Ocvirk+08

1003 Mpc3 includes gas, AGN etc. (RAMSES: Teyssier et al)

ω = x v Δ Vort

• rticity

icity ω ~ 100 km s-1 Mpc-1

Codis+12: motion down filament in co- moving frame generates spin. Local vorticity sets up in plane __ to filament.

|

cold flow down the filament

We use the SAMI mass distribution to simulate the expected signal for the Hector survey:

SAMI: 3600 gals in 0.6 x 1003 Mpc3 (1dF: 2015-18) Hector-1: 20000 gals in 2 x 1003 Mpc3 (2dF: 2019-23) Hector-2: 60000 gals in 6 x 1003 Mpc3 (3dF: unfunded)

Bryant+15

New work from Sandrine Codis

(see also Codis+15) Signatures at z~1, want to extend to z~0.

A: galaxy spin aligns with tidal tensor (e1 points down filament) for low mass galaxies, opposite for high mass. B: blue galaxies align, red galaxies not so much. C: tensor contribution mostly < 3 Mpc but detectable to 10 Mpc.

A B C

Same volume as SAMI Same volume as SAMI but 20x mor but 20x more galaxies; e galaxies; some cosmic variance. some cosmic variance. If true, some galaxy If true, some galaxy pr propert

• perties ar

ies are af e affected fected by lar by largest scales. gest scales.

Align Perp.

Integral field spectroscopy Integral field spectroscopy is giving us a new angle on environmental effects. But we need “cosmological” “cosmological” samples across large-scale structure at high density, cf. Stripe 82.

STRIP IPE 82: 82: 16000 galaxies to rp ~ 17.7 (3o thick)

Planned IFS surveys will get us to ~105 galaxies within a decade. The biggest omission is the lack of HI

• bserva:ons for similar or larger

samples…

Gas supply – missing ingredient in all surveys:

Deep 21cm (≤1019 cm-2) maps of nearby galaxies & groups only exist for small samples ~ 1000 galaxies. Austral Australian surveys wil ian surveys will del l deliver ~10 iver ~105 galaxies galaxies wit within 3 yr hin 3 yr, ~10 , ~106 galaxies wit galaxies within 7 yr hin 7 yr. . ASKAP 36 dishes Wallaby, Dingo surveys Deepest to date: Deepest to date: M31-M33 map reaches ~1017 cm-2 (Wolfe+16).