1. No category

　NRO UM 2014/7/23-­‐24 Extended Study of Faint Submillimeter Galaxies with Mul9field Deep ALMA Data Seiji Fujimoto, Masami Ouchi, Yoshiaki Ono (University of Tokyo) Abstract： Since SMGs are generally known for having much higher a star formaJon rate (SFR; ~100-­‐1000M⊙/yr ) than local galaxies with plenty of dust, SMGs play a very important role in studying star formaJon acJvity in the early universe. So far bright SMGs are the main target in such studies. This is just because the poor ability of the observaJons. Thus, “faint” SMGs which have lower SFR (< 100 M⊙/yr ) haven’t yet been studied much; the number density; the properJes; and the contribuJon to the large scale like extragalacJc background light (EBL). To deal with this, we use the archive data of ALMA. From 27 deep fields’ data at band6, we detect 26 faint SMGs whose flux < 1.0mJy. By using these SMGs and bright ones which are reported in previous works, we gain a reliable Number Count at 1.2mm. In this poster, based on the Number Count, we would introduce staJsJcal property and the contribuJon of faint SMGs to EBL. Moreover, we would like to show some insights to galaxy evoluJon with faint SMGs from esJmaJng the cosmic dust abundance. 1. Number Count of Faint SMGs:
2. Discussion:
Sample SelecJon: ALMA archive -­‐ band6, 7 2.1 ContribuJon to extragalacJc background light (EBL).
Detect image
PB cr = 0.25 PB limit n(S) = Σ ξ(S)
Result.
S/N
EffecJve area
1
1
Bright SMG ~ 2 % ~0.06 mJy
0.1
Faint End of SMG ??
1
10
Slimit(mJy)
IntegraJon of the Number Count and the contribuJon to EBL.
completeness
contaminaJon rate
ξ(S): effecJve number count fc(S): contaminaJon rate C(S): completeness Aeff(S): effecJve area 10
10
0.1
0.01
fc(S/N)とC(S/N)例
(binned)
Fiant SMG ~ 50 % 0.1
−> 26 faint SMGs are detected in 27 fields. Fc(S/N) C(S/N)
EBL (Fixsen+98)
Ono+14
Integrated S (Jy deg-2)
Resolved Fraction(%)
•  Integrated Jme > 100 s •  Within PB correcJon > 25 % area •  No QSO or AGN in map •  Source S/N > 3.6σ 100
Integrates the number count down to the observed flux (~0.1 mJy) •  The contribuJon of bright SMG to EBL is small. •  ~50% of EBL is resolved as Faint SMGs. •  The reaching point of the integral line to 100% of resolved fracJon -­‐> Faint End of SMG~0.06mJy??
2.2 Compare to PACS sample.
With assumpJon, two ranges of redshir Luminosity FuncJon from data of PACS (100μm) is converted into Number Count at 1.2mm. This work (Schechter)
LF: z~1.8-­‐2.3 LF: z~0.4-­‐0.7 Observed in PACS (100μm) -­‐> It clearly shows the trend that higher redshir sources dominates more in 1.2mm Number Count. The contribuJon of luminosity funcJons (z=0.4-­‐0.7, AssumpJon •  SED is based on graybody •  β=1.8 •  Td – IR relaJon (Symeonidis+13) •  <z> = 0.55, 2.05 1.8-­‐2.3) to the Number count at 1.2mm
2.3 Cosmic Dust abundance of SMG.
AssumpJon: •  Number count -­‐> Schechter FuncJon (My work + H13, K13) •  Flux range of SMGs -­‐> 0.1 – 10.0 mJy •  Red shir range of SMGs -­‐> 1.0 – 5.0, <z> = 2.6 (Yun+11) •  M_dust: Sν = κνBν(T) Mdust DL-­‐2 ConverJng the Number Count (1.2mm) to dust mass funcJon, integrates..
Menard et al. 2012
All dust produced
Number count @ 1.2mm with previous studies.
Since we use more sample fields (factor ~3 than Ono+14), we can gain a reliable Number count.
Cosmic abundance of dust locked in SMGs: ~ 5.5×10-­‐6 -­‐> ~57% of all dust (Fukugita
+11) Cosmic dust abundance
Dunne+11 Fukugita+11 Menard+12
This work