Spatially  resolved  star-­‐forming  main-­‐sequence  in  local  LIRGs
東京⼤大学

本原研M2 ⼤大橋宗史

Abstract• Luminous  Infrared  Galaxies(LIRGs)   have  spatially  resolved  Star-‑Formation  Main-‑Sequence(SFMS)• locates   above  the  normal  galaxiesʼ’  SFMS
• interacting  LIRGs  have  higher  sSFR(=ΣSFR/ΣM*)  than  isolated  ones
• we  havenʼ’t  reached  conclusion,  so  any  comments  are  welcome!

Outline
1. Introduction• Star-‑Formation  Main-‑Sequence  (SFMS)• Spatially  resolved  SFMS
2. Data  and  Analysis
3. Results
4. Discussion
5. Future  Works

1.  Introduction• The  study  of  galaxies  with  large  samples  results  in  the  derivation  of  statistical   and  systematic  studies

Star-‑Formation  Main-‑Sequence  (SFMS)• the  relation  between  stellar  mass  and  SFR
• studied  with  various  wavelength  and  in  various  redshifts

redshift  evolution

Renzini &  Peng  15

Whitaker+14

Star-‑Formation  Main-‑Sequence  (SFMS)• Whatʼ’s  the  physical  origin  of  SFMS?
• combination  of  various  processes  in  various  scales• pc  scale  :  molecular  cloud,  HII  region,  …
• kpc scale  :  disk,  halo,  …
• Mpc scale  :  outflow,  accretion,   …
• many  teams  are  trying  to  reconcile  SFMS by  cosmological   simulation  • e.g.  Sparre+15(Illustris simulation),  Torrey+14• but  more  sophisticated   treatment  of  feedback  or  resolution  is  necessary

Spatially  Resolved  SFMS
• the  tight  relation  of  Σmass and  ΣSFR also  exists  in  sub-‑kpc scaleMaragkoudakis+17
Σ*← 3.6um
ΣSFR ← 8um

Abdurro'uf+17
Σ* ,ΣSFR ← SED  fitting

Spatially  Resolved  SFMS
• the  tight  relation  of  Σmass and  ΣSFR also  exists  in  sub-‑kpc scale• log 𝑆𝐹𝑅 = 𝛼	  log	  (𝑀∗ ) + 𝛽
resolved SFMS  @z~∼0αβσ

Cano-‑Diaz+160.72-‑7.95

0.23

Maragkoudakis+170.91-‑9.01

0.31

Abdurro'uf+171.00-‑9.58

NA

global SFMS  @z~∼0αβσ

Cano-‑Diaz+160.81-‑8.340.20

Renzini &  Peng  150.76-‑7.64

NAWhitaker+140.70-‑6.97

0.34

IMF,  SFR  tracer,  extinction   curve  etc.  can  explain  the  difference.
(Speagle+14)

Abdurro'uf+17
Σ* ,ΣSFR ← SED  fitting

Spatially  Resolved  SFMS
• the  tight  relation  of  Σmass and  ΣSFR also  exists  in  sub-‑kpc scale• limited  wavelengthØspatial  resolutionØfew  studies

Maragkoudakis+17
Σ*← 3.6um
ΣSFR ← 8um

Abdurro'uf+17
Σ* ,ΣSFR ← SED  fitting

Spatially  Resolved  SFMS  in  LIRG
LIRG  (Luminous  Infrared  Galaxy)• most  of  them  are  merging  or  interacting• actively  star-‑forming  (≧10Msun/year)• high  dust  extinction  (Av~∼4mag)• possible  to  spatially  resolveØPaα(λ=1.875um)  is  a  good  tracer  of  spatially  resolved  SFMS
• Apaα~∼0.6

Outline
1. Introduction
2. Data  and  Analysis• Data• Analysis
3. Results
4. Discussion
5. Future  WorksData• 19  LIRGs  were  observed  by  mini  TAO/ANIR  in  Ks  and  Paα
• no  AGN,  D  ~∼  80Mpc(z~∼0.005)• 7  are  interacting  (merging,  merger  remnant,  etc.)• 3  are  isolated• 9  are  to  be  determined
PaαKs• some  of  them  have  CO(1-‑0)  data  obtained  by  ALMA

• 17  LIRGs  with  AGN
• assume  pixels  @r>1.2”  is  not  affected  by  AGN
• spatial  resolution• 0.6”(=0.24kpc)  ~∼  2.9”(=1.2kpc)

5 kpc
NGC5257; Tateuchi+15, interacting LIRG

Analysis• mass  surface  densityØΣ𝑀 /Σ2 = 	  0.8	   Σ9∗ ,; /Σ9345 	  (Bell+03)
345∗• SFR  surface  densityØΣ<=> = 6.4 ∗ 10BCD	  ΣEFGH [Msun/yr/kpc2]  (Rieke+09)
extinction  is  not  corrected• not  follow  uniform  dust  screen  model  (Kobayakawa+16)• extinction  map  is  necessary

Outline
1. Introduction
2. Data  and  Analysis
3. Results• global  SFMS
• spatially  resolved  SFMS
4. Discussion
5. Future  Works

Results  1.  global  SFMS
• LIRGs  lie  above  the  local  SFMS

Renzini &  Peng  15• LIRGs  are  heavy  and  starburst

Results  2.  Spatially  Resolved  SFMS
• LIRGs  also  lie  above  the  local  SFMS
resolution  ~∼  0.24  kpc

resolution  ~∼  1.2  kpc

Results  3.  SFMS  in  each  galaxy

clumpic1623,  merging

ugc02982,  isolated  galaxy

Results  4.  SFMS  of  normal  pixels  in  AGN
• HII  pixel  in  HII  galaxies• HII  pixel  in  AGN  :  r>1.2”  (~∼FWHM  of  PSF  x2)
• AGN  pixel  :  r<1.2”• there  is  no  big  difference• no    AGN  feedback?
• stellar  feedback  dominates?

IC1623
NGC1614

Discussionüinteracting  LIRGs  have  high  sSFR
• 0.3dex  above  isolated  LIRGs
1. locally  have  more  molecular  gas?  (=high  fgas)
2. high  SFE?
ügravitational   tidal  torque  (Hopkins+09)
üshock-‑induced  gas  compression  (Saitoh+09)
3. miss  align  with  gas  and  stellar?

Tacconi+13
local  normal

resolution  ~∼  0.24  kpc

Discussion

resolution  ~∼  0.24  kpc

resolution  ~∼  1.2  kpc

相関係数

spatial  resolution  can  change  the  Main  Sequenceücorrelation  between  ΣSFR  and  ΣM*  fades  in  high  resolution  (<0.6kpc)
Øneed  to  check  this  in  normal  galaxies
1. break  of  KS  law?
2. variety  of  fgas
3. unique  scale  of  SF  that  M* contributes?

highresolution

lowBigiel+08

Discussion
1.  local  KS  law
• does  not  change  with  resolution  in  R=300pc~∼1000pc   (Bigiel+08)• breaks  in  local  LIRG,  IC4687  @250pc  resolution  (Pereira-‑Santaella+16)
the  distribution  of  CO  and  ionized  gas  is  different  <75pc  resolution  (Schruba+10)

Pereira-‑Santaella+16

one  galaxy  have  various  local  fgas=Σgas/(Σgas+ΣM*)• Σgas =  ΣCO(1-‑0)major  merger  w/  multiple  nuclei

minor  merger

2.  local  gas  fraction

single  galaxy

Discussion

Larson+16
ic1623

ic1623  @0.8kpc  resolution

3.  unique  scale  that  M*  contributes  to  SF• gravitational   instability  is  driven  mainly  by  Stars  (Romeo+17)• the  scale  of  instability  ≧ 1kpc
Øwe  could  not  have  enough  data  points  at  this  resolution• at  ≦ 1kpc,  molecular  gas  drives  instabilityØwe  need  more  molecular  gas  data  of  LIRG= 2𝜋	  𝜎/𝜅Discussion

Romeo+17

Conclusion• LIRGs lie  above  the  local  SFMS
• LIRGs  also  have  spatially  resolved  SFMS
• the  MS  locates  0.3  dex above  the  local  normal  one• interacting  LIRGs  locate  above  isolated  LIRGs
Øextinction  correction  can  stands  out  the  difference• spatial  resolution  can  change  the  main-‑sequenceFuture  Works• extinction  correction
ümake  extinction  mapüBalmer decrement  with  Paα and  Paβ  or  Hα• cf.  densest  region  of  LIRG  have  AK~∼3  (Pereira-‑Santaella+16)• study  the  local  KS  law  in  LIRG
ühigh  SFE/fgas?
üαCO problem