dusty star-forming galaxies at z > 4 with ska2 (& ska1)
Post on 22-Mar-2022
1 Views
Preview:
TRANSCRIPT
‘SKA1 Continuum Science Assessment Workshop’ | Sep 10, 2013
Dusty star-forming galaxies at z > 4 with SKA2 (& SKA1)
M. Sargent (U. of Sussex)
with E. Daddi (CEA), M. Béthermin (ESO/CEA)
The 2-SFM decomposition…
Sargent+ ’12 Distribution of (massive) star-forming galaxies at 1.5 < z < 2.5 w.r.t (s)SFR & M✭ (Rodighiero+ ’11):
Mass-invariant decomposition into 2 log-normal distributions (‘normal’ & starbursting galaxies, resp.).
M. Sargent
z = 2: starburst contribution to SFRD [M⦿/yr Mpc-3]: ~14% (cf. Kaviraj+ ’12)
(If description is extendable to unsampled mass range.)
2 Sep. 6, 2013
Cause(s) & effect: Interpreting the decomposition…
➽ main-sequence activity? ➽ starbursts?
A snapshop at z ~ 2, prior to measuring (s)SFR distributions… Dark matter accretion spec-trum in cosmological simu-lations (Dekel+ ’09; Goerdt+, in prep.): § smooth accretion
§ clumpy accretion with major mergers in high-MDM tail
.
3 M. Sargent Sep. 6, 2013
Sep. 6, 2013 4
Stellar MF of star-forming galaxies, z < 4: (also: Muzzin+ ‘13, Santini+ ‘12, Ilbert+ ’10, Marche-sini+ ’10, Pérez-González+ ‘08, Fontana+ ’06, …)
Stellar mass function evolution
Ilbert+ ‘13
Evolution of M*& Φ*:
Sep. 6, 2013 5
1) stellar mass fct. of star-forming galaxies
e.g.: Pozzetti+ ‘09
2) SB+MS decompo-sition at fixed M★
Sargent+ ’12
3) redshift-evolution of sSFR of main seq.
e.g.: Reddy+ ’12
IR LFs: pre-Herschel (Sargent+ ‘12)… … & using Herschel (Gruppioni+ ’13)
Jan. 17, 2013
SFR distribution functions…
6
… or equivalently: radio luminosity functions (based on the observed evolution of normal and starburst galaxies; has no ad-hoc tuning or free parameters.)
similar to local 1.4 GHz “monster” and “normal” galaxy split of luminosity fct.
SFR [Msun/yr]
IR number counts (Béthermin+ ‘12):
Sep. 6, 2013 7
1) stellar mass fct. of star-forming galaxies
e.g.: Pozzetti+ ‘09
2) SB+MS decompo-sition at fixed M★
Sargent+ ’12
3) redshift-evolution of sSFR of main seq.
e.g.: Reddy+ ’12
IR SEDs for MS & SBs (e.g. Elbaz+ ‘11)
CIB cross power spectra (Béthermin+ ‘13):
Sep. 6, 2013 8
DM simulations (Pichon, Teyssier)
1) stellar mass fct. of star-forming galaxies
e.g.: Pozzetti+ ‘09
2) SB+MS decompo-sition at fixed M★
Sargent+ ’12
3) redshift-evolution of sSFR of main seq.
e.g.: Reddy+ ’12
Galaxies distributed throughout cosmic web w/ abundance matching
Sep. 6, 2013 9
Predictive power of the empirical 2-SFM approach for high-z star-forming galaxies:
Redshift-distribution of SPT sources (Weiss+ 13)
Redshift-distribution of SCUBA-2 450 um sources (Roseboom+ 13)
Sep. 6, 2013 10
Condon+ ‘12 Béthermin+ ‘12
Source counts…
10 n
Jy
1 uJ
y
flux distribution for star- forming galaxies only
Sep. 6, 2013 11
At what redshifts are these sources?
The higher the flux limit, the harder it gets to any detect high-redshift sources that are not lensed.
Increasing sensitivity does not strongly alter the redshift distribution beyond 10 uJy.
flux cut # z>4 [deg2] # z>6 [deg2] # z>8 [deg2] 100 nJy ~11000 ~610 ~12 10 uJy ~25 ~0.04 ~0.0001
Sep. 6, 2013 12
(Additional advantage of high-freq. coverage up to 14 GHz: detectability of CO at z>9.)
Radio-only, high-z source selection
Mannucci+ ‘10
But…! What if dust emission is essentially absent?
dust-to-radio slope as stand-alone SKA redshift indicator
M. Sargent
Star formation efficiency…
13 Sep. 6, 2013
Karim+ ‘11 Since z = 2.5, main contri- bution to SFRD has come from M★/M ☉≈ 2×1010 ga- laxies… (Consequence of 1. const. Schechter M* of stellar mass fct. of SF galaxies 2. const. slope of main seq.)
Integrated Schmidt-Kennicutt law for main seq. galaxies - tight and slightly non-linear:
Sargent+ ’13a
SFE~5-10
SFE~15-30
What causes the increasing SFE of those galaxies that contribute most to the SFR over the last 11 Gyr?
Sep. 6, 2013 14
… and its link to ISM state (e.g. GMC/clump magnetic struct.)
courtesy of A. Cibinel, W. Rujopakarn, M. Pannella
Cases for high-resolution ü resolved SFR-studies ü morphological AGN/SF separation
M33: “… galactic fields are dynamically important in the cloud formation process (e.g. Li & Henning ‘11)
top related