Kinematics of Circumgalactic Gas: Quasars Probing the Inner CGM of - - PowerPoint PPT Presentation

Kinematics of Circumgalactic Gas:

Quasars Probing the Inner CGM of z=0.2 Galaxies

Crystal Martin & Stephanie Ho (UC Santa Barbara) Glenn Kacprzak (Swinburne) Chris Churchill (NMSU) What Matters Around Galaxies?

Consider the Cool Gas

Illustration of the Milky Way Halo (Putman, Peek & Joung 2012 ARA&A

Strength of Mg II Absorption Depends on Azimuthal Angle

Above: Bordoloi+2011 (zCOSMOS Stacks) See Also: Bouché+2012 (10 galaxies at low redshift; bimodal) Lan+2014 (2000 SDSS pairs at z≈0.5) Does the CGM spin like the disk? e.g., Steidel+2002 (z≈0.6)

Minor Axis Major Axis

ß 200 kpc à Brook+2011 Accretion Outflow

New Observations

• 50 star-forming galaxies redshift at z ≈ 0.2 (from SDSS)
• All have background quasar with b = 90 kpc (inner CGM)
• Keck/LRIS spectroscopy of MgII absorption (quasar sightline)
• Measurements of galactic rotation curve (APO and Keck)
• High-resolution infrared imaging with Keck/NIRC2

Star-forming Galaxies

Mg II Doublet -- Quasar Sightline Galaxy Spectrum

Quasars Probing Galaxies: Outflow Example

Fitted Model: V = 40-80 km/s; SFR = 5-15 Msun/yr; h= 0.1-0.9

Kacprzak, CLM, Bouche + 2014

Viewed at Disk Inclinations > 45°

CLM+2017

Geometrical Considerations:

• 1. Azimuthal Angle

Disk Major Axis Disk Minor Axis Disk Major Axis Disk Minor Axis DATA PARADIGM

20 40 60 80 100 Major Axis (kpc) 20 40 60 80 100 Minor Axis (kpc) α b

Mg II detection No Mg II detection Less certain

Which Sightlines Show Mg II Absorption?

20 40 60 80 100 Major Axis (kpc) 20 40 60 80 100 Minor Axis (kpc) α b

LRIS Sightline

Same Distribution?

• No. P ≈ 10%

CLM+2017

20 40 60 80 100 Major Axis (kpc) 20 40 60 80 100 Minor Axis (kpc) α b

Mg II detection No Mg II detection Less certain

20 40 60 80 100 Major Axis (kpc) 20 40 60 80 100 Minor Axis (kpc) α b

Mg II detection No Mg II detection Less certain

Absorption Strength Depends on Azimuthal Angle

Absorption is weaker at intermediate azimuthal angles.

Equivalent Width Dependence of Mg II Absorption

20 40 60 80 100 Major Axis (kpc) 20 40 60 80 100 Minor Axis (kpc) α b

Mg II detection

20 40 60 80 100 Major Axis (kpc) 20 40 60 80 100 Minor Axis (kpc) α b

Mg II detection Less certain

20 40 60 80 100 Major Axis (kpc) 20 40 60 80 100 Minor Axis (kpc) α b

Mg II detection

W2796 > 1000 mA 300 mA < W2796 < 1000 mA 100 mA < W2796 < 300 mA Optical Depth (t >> 1): Largest velocity spread at small a and small b Optical Depth (t ≈ 1-10): Large velocity spread at large a and all b

• Opt. Depth (t < 1):

Similar Mg+ column density at all (a,b)

Interpretation of Spatial Variation in W2796

20 40 60 80 100 Major Axis (kpc) 20 40 60 80 100 Minor Axis (kpc) α b

Mg II detection

20 40 60 80 100 Major Axis (kpc) 20 40 60 80 100 Minor Axis (kpc) α b

Mg II detection Less certain

20 40 60 80 100 Major Axis (kpc) 20 40 60 80 100 Minor Axis (kpc) α b

Mg II detection

Optical Depth (t >> 1): Largest velocity spread at small a and small b Optical Depth (t ≈ 1-10): Large velocity spread at large a and all b

• Opt. Depth (t < 1):

Similar Mg+ column density at all (a,b) Selects Gas Rotating with Disk Gas Disturbed by Galactic Wind (q=30o-40o) Small differences in metal column

Major Axis Sightlines

Kinematics of Gas Near the Disk Plane

• 1. Halo gas rotates in same direction as galactic disk.
• 2. Circular orbits would produce a larger Doppler shift.
• 3. Inflow in the disk plane can explain observed kinematics.

Ho, CLM, et al 2017, ApJ, 835, 267

Mg II Doppler Shifts & Galactic Rotation

Ho, CLM, et al 2017, ApJ, 835, 267

Mg II in Quasar Sightlines Galaxy Rotation Curves

Doppler shifts in quasar sightlines correlated with disk rotation

• .

Ho, CLM, et al 2017, ApJ, 835, 267

Mg II in Quasar Sightlines Galaxy Rotation Curves

Some of the absorption components are not on circular orbits

• .

Ho, CLM, et al 2017, ApJ, 835, 267

Models for Individual Sightlines

• Disks cannot produce absorption on both sides of Vsys.
• Thin disks produce a narrow profile.
• Fitting disks models has awkward implications (Heff ≈ rvir).

Ho, CLM, et al 2017, ApJ, 835, 267

Inflow Model Predicts Sign of Disk Inclination

Ho, CLM, et al 2017, ApJ, 835, 267

Where is the Mg II Doppler Shift Correlated with the Direction of the Disk Rotation?

O: Aligned X : Not Aligned : Systemic Major Axis Sample At low impact parameter, alignment persists to larger azimuthal angles.

Geometrical Considerations:

• 2. Disk Inclination

X : Not rotating in direction of galactic disk At each position, we compare Mg II Doppler shift to projected disk

• rotation. Find

V (MgII) < V (disk)

Detecting Kinematic Signatures of Disk Accretion

b < 75 kpc ≈ 0.5 RVIR v

Stewart et al. (2013)

Take Away Points: Kinematics of the z≈0.2 CGM

• Small impact parameter

sightlines find large, R ≈ 80 +/- 10 kpc, disks of cool gas.

• The gas is not primordial

because it’s detected in Mg II.

• Requires a substantial inflow

velocity.

• Inflows contribute to prolonging

disk star formation.

• Angular momentum matters in

the CGM, and observations can measure it.

20 40 60 80 100 Major Axis (kpc) 20 40 60 80 100 Minor Axis (kpc) α b

Mg II detection No Mg II detection Less certain

Borthakur+2015, COS-GASS

Looking Forward:

• 1. Comparison to Gas Disks in EAGLE

Disk at z=0.271; disk radius ≈ 50 kpc

20 40 60 80 100

rshell (kpc)

5 10 15 20 25

|jparticle| (×10−3 pkpc * km/s) r = 50 kpc

Stephanie Ho, Monica Turner, Joop Schaye, CLM

Looking Forward:

• 2. How is the Minor Axis Gas Disturbed?
• Typical z≈0..4-0.9 galaxies have
• utflows with h ≈ few. Gas
• bserved down the barrel is near

the galaxy (1-10kpc). Gravity pulls much of it back.

• At z≈0.2, we are looking at the

CGM a few Gyr later. Winds have disturbed the CGM above the disk plane.

• 100 kpc @1000 km/s in 108 yr
• 100 kpc @100 km/s in 109 yr

CLM+2012; Kornei+2012