Circum-galactic Medium Around Local Spiral
Galaxies – A New Window to Understand
Galaxy Evolution
Li Jiang-Tao
1. Service d’Astrophysique, CEA, Saclay, France
2. Department of Astronomy, University of Michigan, Ann Arbor, USA
Outline
•1. Introduction
•2. Diffuse X-ray observations of the hot CGM
•2.1. The sample
•2.2. X-ray scaling relations
•2.3. Compare to cosmological simulations
•2.4. Massive spiral galaxies
•3. UV absorption line observations of the cool CGM
•4. Radio observations
•5. Summary and Prospect
1. Introduction
AGN
What do we study of galaxy formation and evolution?
Stellar component (bulge+disk)
Star formation (SF)
Dark matter halo
A typical spiral galaxy
What we still don’t The gaseous halo or the circumgalactic medium (CGM),
know well?
compared to intergalactic or intracluster medium (IGM or ICM).
• Why it is important to study the CGM?
•
•
Role of CGM in galaxy evolution: Gas reservoir to continue SF and depository of chemical
and mechanical feedback .
Studying CGM help us to understand the environment of galaxies, or the galactic ecosystem.
Some big puzzles of galaxy evolution:
•
•
•
•
•
•
•
•
•
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Missing satellite problem
Why the number of dwarf galaxies is much
less than predicted?
Overcooling problem
Why the gas cooling rate is much less than
predicted?
How feedback works?
What are the temperature, metallcity, mass,
ionization state, and velocity of the
outflows?
Where they interact with the accreted gas?
Could feedback efficiently stop accretion and
quench SF?
Missing baryon problem
…
• Why it is difficult to study the CGM?
• Theoretically, adding hydrodynamics over large range of physical scale
(from single SN to at least cluster of galaxies) is very time consuming.
• Observationally, the multi-phase CGM is always too faint to detect.
• Could we study the CGM now?
• Yes!
What is the CGM gas comprised of?
Metal line radiative cooling curve
Sutherland & Dopita 1993, ApJS, 88, 253
Warm; 104-5K;
Hot; >106K or
UV emitting
0.1keV; X-ray
Cold; <104K;
emitting
HI or CO
What kind of observations do we need?
1. X-ray observations of the hot CGM.
2. UV absorption line studies of background AGNs to study warm-hot intergalactic medium
(WHIM) and cold gas around foreground galaxies.
3. Radio observations of the cold molecular and atomic gases.
2. Diffuse X-ray observation of the hot CGM
2.1. The sample
Li & Wang 2013a,b, MNRAS, 428, 2085; 435, 3071
Chandra sample of 53:
Subsample definition:
Nearby : distance<30Mpc
Edge-on : inclination>60◦
Disk galaxy: S0/spiral (-3<TC<9)
Moderate size : 1’<D25<16’
Low Extinction : NH<8e20cm^-2
No X-ray bright AGN
Starburst (f60/f100>0.4 and LIR>3e43erg/s) vs
non-starburst
Clustered (ρ>0.6) vs field
Early-type (TC<1.5) vs late-type
2.2. X-ray scaling relations
NGC4438: 87ks XMM-Newton Cycle 13
observation (PI: Jiang-Tao Li, but as
Priority C) plus many multi-wavelength
observations.
NGC660: 50ks Suzaku Cycle 9 observation
(PI: Jiang-Tao Li, but as Priority C).
Not the end!
LX has a linear correlation with ĖSN. The Xray radiation efficiency η≡LX/ĖSN~0.4%.
2.3. Compare with
cosmological simulations
Observations of massive spiral galaxies from the literature (blue).
Galaxies-Intergalactic Medium Interaction Calculation (GIMIC) (green;
Crain et al. 2009, MNRAS, 399, 1773 ; 2010, MNRAS, 407, 1403).
Li, Crain, & Wang, 2014,
MNRAS, 440, 859
GIMIC well reproduce
both the range and
scatter of the corona
luminosity for L* galaxies.
LX
LX
However, GIMIC has:
vrot
(1) No AGN feedback
(2) Constant SNe feedback
parameters (wind
velocity and mass
loading factor).
(3) Single phase ISM, so no
cool-hot gas interaction
below the numerical
resolution.
LX
M200
M200
Abundance matching
(Leauthaud et al. 2012, ApJ, 744, 159).
SFR
M
OWLS & GIMIC projects taught us much about physical modeling,
so major physical improvements by Eagle:
and collaborators
from many other
institutes.
Looking
forward to
the results
from new
simulations.
The first
EAGLE paper
is already on
astro-ph!
(1) Non-constant wind velocity, wind remain hydrodynamically coupled.
(2) Switching to thermal SNII feedback, parametrized by heating
temperature and energy fraction.
(3) AGN feedback, seed black holes of mass (105 Msun) are injected into
FOF haloes of a threshold mass.
Tuning the EAGLE Universe to match the galaxy stellar mass function
(GSMF) and further perform comparisons with:
(1) X-ray scaling relations and abundances
(2) Local Tully-Fisher relation
(3) Cosmic SNIa rate
(4) Local specific star formation rates
(5) Local gas phase and stellar metallicities
(6) Local alpha/Fe abundance
2.4. Massive spiral galaxies
Most of the X-ray emission is produced by the high-density, high-metallicity gas directly
related to stellar feedback. It is more important to search for X-ray emission from externally
accreted gas, which is expected to be strong in isolated SF-inactive massive spiral galaxies.
Why massive galaxies above a transition mass of ~2X1011Mʘ are X-ray brighter (higher LX/M*)?
(a) Stronger thermal/ram-pressure
confinement (Dalla Vecchia & Schaye 2008,
MNRAS, 387, 1431; Lu & Wang 2011,
MNRAS, 413, 347).
(b) Major accretion mode changing from
cold-mode to hot-mode (e.g., Keres et
al. 2005, MNRAS, 363, 2).
(c) Steeper density profile due to
hydrostatic or inflow state (Ciotti et al.
1991, ApJ, 376, 380; O’Sullivan et al.
2003, MNRAS, 340, 1375).
We need more deep X-ray observations of
massive galaxies around or above the
transition mass to confirm the existence
of such a LX-M* slope change.
XMM-Newton Cycle 13 Large program
(490ks of 5 galaxies; PI: Jiang-Tao Li)
NASA ADAP 3 year funding; Science PI: Jiang-Tao
Li (UMich), Program PI: Joel N. Bregman (UMich);
Co-I: Q. Daniel Wang (UMASS)
Selection criteria:
(1) Massive: vmaxg≳300km/s and M∗≳2×1011 M⊙.
(2) Quiescent: SFR/M∗<0.05 Gyr−1.
(3) Isolated: no bright companion within 30' (600 kpc at a distance of 70 Mpc).
(4) Optimized for X-ray observation: NH<1021cm−2; distance<100Mpc.
(5) Add archival data: 4 galaxies in the table, and another two (NGC6011, 45ks and NGC7490,
41ks by Akos Bogdan also in this cycle)?
Major scientific goals:
(1) Better constrain the metallicity.
(2) Radial distribution to larger radii (plus (1) to measure the baryon content).
(3) X-ray scaling relations with more galaxies around/above the transition mass.
3. UV absorption line observations of the cool CGM
AGN UV absorption line
observations is one of the
primary scientific objective
of HST.
(Bahcall & Spitzer 1969, ApJ,
156, 63)
AGN UV absorption line is
the best way to study the
warm-hot intergalactic
medium (WHIM).
1. Strong extinction and
usually too faint for UV
imaging (Hodges-Kluck &
Bregman 2014, ApJ, 789,
131).
Bregman 2007, ARA&A, 45, 221
2. Correct temperature
range and lower column
density (than X-ray).
Some HST large projects studying AGN absorption lines since COS (the Cosmic Origins
Spectrograph) was installed in May 2009:
Probing Warm-Hot Intergalactic Gas at 0.5 < z < 1.3 with a Blind Survey for O VI, Ne VIII, Mg X, and Si XII
Absorption Systems Cycle 17 ; PI : Todd Tripp ; 137 orbits
How Galaxies Acquire their Gas: A Map of Multiphase Accretion and Feedback in Gaseous Galaxy Halos
Cycle 17 ; PI : Jason Tumlinson ; 134 orbits ; COS-Halos
A COS Snapshot Survey for z < 1.25 Lyman Limit Systems
Cycle 18 ; PI : J. Howk ; 140 orbits
How Dwarf Galaxies Got That Way: Mapping Multiphase Gaseous Halos and Galactic Winds Below L*
Cycle 18 ; PI : Jason Tumlinson ; 129 orbits ; COS-Dwarfs
Understanding the Gas Cycle in Galaxies: Probing the Circumgalactic Medium
Cycle 19 ; PI : Timothy Heckman ; 119 orbits
A Breakaway from Incremental Science: Full Characterization of the z<1 CGM and Testing Galaxy Evolution
Theory
Cycle 21 ; PI : Christopher Churchill ; 110 orbits
The COS Absorption Survey of Baryon Harbors (CASBaH): Probing the Circumgalactic Media of Galaxies from
z = 0 to z = 1.5 Cycle 22 ; PI : Todd Tripp ; 99 orbits
Limitation: Most of the absorbers are at z>0.1, in order to include the important OVI
λλ1032,1037 lines in the COS range (e.g., Tumlinson et al. 2011, Science, 334, 948).
Bregman et al. 2013, ApJ, 766, 57
What is difficult to do with the current data?
1. Associate the absorber to the host galaxies.
2. Detail host galaxy properties (e.g.,
distribution of SF in the galactic disk)
3. The cold and hot CGM.
We are focusing on local galaxies already
have or potentially easy to propose high
quality multi-wavelength observations!
Sightline map of COS-Halos
4. Radio observations
CHANG-ES: Continuum HAlos in Nearby Galaxies
— an EVLA Survey (PI: Judith A. Irwin).
405 hours of EVLA observations of 35 nearby
edge-on galaxies over two wide bandwidths
centered at 1.5 and 6 GHz and in three (B, C and
D) array configurations.
L-band (1.5GHz) contour overlaid on X-ray
image (Irwin et al. 2012, AJ, 144, 44)
NGC 4631
Evidence for magnetic confinement
(Wang et al. 2001, ApJL, 555, 99)?
The relation between X-ray and radio halo
remains to be investigated!
>20 CHANG-ES galaxies have high quality X-ray
data, and we are working to obtain more (e.g.,
XMM-Newton AO-10 program; 56ks taken, 37ks
Priority C; PI: Jiang-Tao Li).
CHANG-ES Paper IV (van Vliet Wiegert et al. 2015) on D-array observations of extended radio
halo is coming!
5. Summary and Prospect
1. In addition to the stellar
component (through optical
or IR observations), we are
now ready to study the multiphase gaseous CGM around
local galaxies (through X-ray,
UV, and radio observations),
which finally close the box of
the baryon budget and greatly
help to constrain the galaxy
evolution models.
Baryon budget of a fiducial COS-Halos galaxy;
Werk et al. 2014, ApJ, 792, 8
2. Theoretical works are also
accurate enough to
quantitative compare with
observations.
3. It is even possible to study other phases of the CGM (in addition to the stars, gases, and
dark matter), such as the magnetic field and cosmic ray. It is also time to consider their roles
in galaxy evolution (e.g., Pakmor et al. 2014, ApJ, 783, 20).
We are on the way to fully understand the
whole baryonic Universe……………………
Thank you very much!