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Constraining*the*MW's*CGM*with*the*LMC*
Gur4na*Besla,*Munier*Salem*
Greg*Bryan,*Mary*Putman,*Roeland*van*der*Marel*


The Magellanic System*
Gas*exchange*&*removal*by*dwarfUdwarf*interac4ons* DLA's/Bimodality*"**1021*­*1019*/*cm2**over*200o*x*10o* Survivability*of*Cold*Streams?* Leading Arm

Putman+*2003**

Bridge
Kerr 1954

Magellanic Stream
Mathewson + 1974, 1977 Dieter 1965; van Kuilenberg 1972 Wannier & Wrixon 1972

SMC

LMC
Nidever+ 2010

MGas

*outside*~*

2"x109"M!(d/55*kpc)2*>*2*x*MGas

*LMC+SMC

***Fox+"2014"


Rtrunc*

(BRIDGE,*SMC)*

Salem,*Besla*et*al.*in*prep*


~*1011*M!

*

7.2*x*108*M!

*

2.7*x*109*M!

*

Ram*Pressure**"***gas*density**x*velocity2*


The*Recent*Pericentric*Passage*of*the* LMC*about*the*MW*is*Model*Independent*
Gomez,*Besla*et*al.*2015*;**

Kallivayalil,*van*der*Marel,*Besla*et*al.*2013**


Following*Miller*&*Bregman*2015,*2013*

MW gas halo density

hi core

mid core

lo core

nperi rperi
galactocentric radius


Resolu4on:** 30*pc** * No*cooling* * *

Salem,*Besla*et*al.*in*prep* Enzo*AMR*Simula4ons*


0.13*x*10U4**/cm3*

1.2*x*10U4**/cm3*

7.44*x*10U4**/cm3*

Salem,*Besla*et*al.*in*prep*


Calibra4ng*the*GunnUGod*Rela4on*

Salem,*Besla*et*al.*in*prep*


Constraints*on*CGM*density*at*~*48*kpc*

Salem,*Besla*et*al.*in*prep*

Es4mates*from*stripping*simula4ons*of*other*MW*Satellites:** *Gado,*Fraternali*et*al.*(2013) *Grcevich*&*Putman*(2009)***

****(1.3*­*3.6)*x*10U4**/cm3* (0.1U10)*x*10U4*/cm3*


Constraints*on*CGM*Density*Profile*
Black*Curves:**Constraints*from*Miller*&*Bregman*2015*

Salem,*Besla*et*al.*in*prep*


Constraints*on*CGM*of*the*Milky*Way*
1012
LMC Peri

10-2

10-3

Mass Enclosed [ Msun ]

1011

density [ cm-3 ]

1010

10-4

10

9

10-5 10
0

10

1

10

2

10

8

101 radius [ kpc ]

LMC Peri

10

2

radius [ kpc ]

Mgas

*smooth

*(R*<*300*kpc)*=*2.6*(+/U*1.4)*x*1010*M!
Salem,*Besla*et*al.*in*prep*

(~12U40%*of*Missing*Baryons*in*1e12*halo)*


Conclusions*
· The*LMC*HI*disk*shows*evidence*of*trunca4on* by*ram*pressure*stripping*in*the*direc4on*of* mo4on*(rtrunc=*6.2*+/U*0.25*kpc)* · Maximal*trunca4on*occurs*at*pericenter,* where*LMC*orbital*proper4es*are*well*known.* · This*provides*a*direct*constraint*on*the*gas* density*of*the*MW's*CGM*at*~*48*kpc* *