# Presentation: 724914

## Cosmic infrared background fluctuations from deep Spitzer images and Population III

*A. Kashlinsky, R. Arendt, J. Mather & H. Moseley*
- (Nature, 2005, 438, 45;  ApJL, 2007,654, L1 and 654, L5; 2007,ApJL, in press)

-  Source-subtracted IRAC images contain significant CIB fluctuations.
-  These fluctuations come from populations with significant clustering component but only low levels of the shot-noise component.
-  There are no correlations between source-subtracted IRAC maps and ACS source catalog maps.
-  These imply that the CIB fluctuations originate in populations 1) z>8 (t<0.5 Gyr), 2) S<10 nJy, and 3) M/L << M/L of present day populations.
-  These populations have projected number density of ~5-10 arcsec-2 and are within the confusion noise of the present-day instruments.
-  JWST can resolve them (beam<0.04”).

*First stars, Santa Fe 2007**	**	**	**	**	**	**A.Kashlinsky*

- If massive, each unit of mass emits L/M~105 as normal stars (~L๏/M๏)
- Pop 3 era contains a smaller volume (~k2c Δt), hence larger relative fluctuations
- Pop 3 systems form out of rare peaks on the underlying density field, hence their correlations are amplified

*Pop 3 leave a unique imprint in the CIB structure - measuring it would offer evidence of and a glimpse into the Pop 3 era (Cooray et al 2004, Kashlinsky et al 2004)*

***CIB fluctuations from Population III***

- SED from Santos et al (2002)

- Spitzer IRAC channels probe regions
- of SED with substantial emissions from
- (model) Pop 3 systems – although the
- emissions probed come from reprocessed
- (by IGM etc) stellar emissions.

*First stars, Santa Fe 2007**	**	**	**	**	**	**A.Kashlinsky*

## Datasets in Spitzer CIB fluctuations analysis(Kashlinsky, Arendt, Mather & Moseley 2005, 2007a,b,c)

| Region | lGal | bGal
 | lecl
 | becl
 | <tobs> | PSN
10-11 nW/m2/sr |
| --- | --- | --- | --- | --- | --- | --- |
| QSO 1700
(or IOC) | 94.4 | 36.1 | 194.3 | 83.5 | Ch 1-3: 7.8 hrs
Ch 4:    9.2 hrs | 5.8 (Ch 1)
6.0 (Ch 2)
60. (Ch 3)
44. (Ch 4) |
| HDFN-E1 | 125.9 | 54.8 | 148.4 | 57.3 | ~ 21 hrs | 1.9 (Ch 1)
1.1 (Ch 2)
12. (Ch 3)
10. (Ch. 4) |
| HDFN-E2 |  |  |  |  | ~ 21 hrs | 1.9 (Ch 1)
1.1 (Ch 2)
12. (Ch 3)
10. (Ch. 4) |
| CDFS-E1 | 223.6 | -54.4 | 41.1 | -45.2 | ~ 24 hrs | 2.2 (Ch 1)
0.9 (Ch 2)
15. (Ch 3)
11. (Ch. 4) |
| CDFS-E2 |  |  |  |  | ~ 23 hrs | 2.3 (Ch 1)
1.1 (Ch 2)
15. (Ch 3)
11. (Ch. 4) |

*First stars, Santa Fe 2007**	**	**	**	**	**	**A.Kashlinsky*

## Image processing:

- Data were assembled using a least-squares self-calibration methods from Fixsen, Moseley & Arendt (2000).
- Selected a field of w. homogeneous coverage.
- Individual sources have been clipped out at >Ncutσ w Nmask =3-7
- Residual extended parts were removed by subtracting a “Model” by identifying individual sources w. SExtractor, convolving them with a full array PSF and removing (parts of) sources via CLEAN algorithm.
- Clipped image minus Model had its linear gradient subtracted, FFT’d, muxbleed removed in Fourier space and P(q) computed.
- In order to reliably compute FFT, the clipping fraction was kept at >75% (Ncut=4)
- Noise was evaluated from difference (A-B) maps
- With GOODS data find the same signal at different detector orientations
- Note: for GOODS data E1 and E2 data must be treated separately
-      because of the (very) different zodiacal gradients.

*First stars, Santa Fe 2007**	**	**	**	**	**	**A.Kashlinsky*

## GOODS – results (color symbols)(black symbols show the QSO1700 field results)

- Fluctuations are made up of two components:
- Remaining shot noise (scales < 20 arcsec)
- Fluctuations arising from clustering (>0.5 arcmin)
- Remaining shot noise is :   PSN = ∫ S2(m) dN/dm dm
- Different datasets must be compared at the same PSN.

- Shot noise reached in QSO1700
- PSN (3.6μm) ≈ 6 x 10-11 nW2/m4/sr
- Shot noise reached in GOODS:
- HDFN-E1, HDFN-E2
- CDFS-E1, CFDS-E2
- PSN (3.6μm) ≈ 2 x 10-11 nW2/m4/sr

*First stars, Santa Fe 2007**	**	**	**	**	**	**A.Kashlinsky*

## Spitzer GOODS vs ACS GOODS(Kashlinsky, Arendt, Mather & Moseley 2007, Ap.J.Letters, in press)

- GOODS fields were observed by ACS/*HST* at B,V,i,z (0.4 to 0.9 micron)
- We selected four regions (HDFN-E1,2; CDFS-E1,2) of 972 0.6” pixels on side (10’)
- Used ACS source catalog (Giavilsco et al 2004) to produce ACS maps for the fields
- Convolved ACS source maps with IRAC 3.6 and 4.5 beams
- Processed IRAC maps as in KAMM and computed fluctuations and cross-correlation
***Results***
- Source-subtracted IRAC maps have very different power spectra than those in ACS
- The amplitude of CIB fluctuations than can be contributed by ACS sources is small
- There are very good correlations between ACS sources and the sources removed by KAMM, but
- Completely negligible correlations between ACS and source-subtracted IRAC maps
***Conclusions***
- ACS sources cannot contribute significantly to KAMM IRAC fluctuations

*First stars, Santa Fe 2007**	**	**	**	**	**	**A.Kashlinsky*

## IRAC/GOODS

- source-subtracted
- CIB fluctuations.
- ACS source maps.
- •    mAB>22
- ♦   mAB> 24
- ▲  mAB > 26
- ■   mAB > 28
- ◊   mAB > 24, no mask
- ACS vs KAMM sources
- (open symbols).
- ACS source maps
- vs source subtracted
- IRAC data (filled).
- Solid lines: ACS B,V,I,z,
- Dotted line: IRAC Ch 1

*First stars, Santa Fe 2007**	**	**	**	**	**	**A.Kashlinsky*

## Extragalactic component of the CIB fluctuations

- Fluctuations arise from mAB > 25.5-26
- Sources of these fluctuations are not in ACS source catalogue
- The measured clustering component at *both* 3.5 and 4.5 μm
- 		δF ~ 0.1 nW/m2/sr at θ > 1 arcmin
- The shot-noise component of fluctuations
- 		PSN < ~ (1-2)x10-11 nW2/m4/sr

- 	Take 3.6 and 4.5 micron data as an example.
***	******Any model must explain the following***:

*First stars, Santa Fe 2007**	**	**	**	**	**	**A.Kashlinsky*

## 1. Magnitude and ACS constraints:

- Shot-noise vs counts:  KAMM remove mAB > 26 at 3.6, 4.5 mic or sources with flux < 150 nJy
- Even at z =5 these sources would have 6x108 h-2LSun emitted at 6000 A, so the sources contributing to the fluctuations are likely at z>5

- Absence of correlations between ACS source catalog maps and source-subtracted IRAC
- maps leads to stronger conclusions. Either
- z>8 (so that Lyman break shifts passed ACS z-band at ~0.85=0.9 micron), or
- KAMM signal is produced by extremely low-L galaxies at lower z which escaped
- 	ACS source catalogue, so mAB >27-28 or in band L<~107LSun

*The likeliest option is KAMM fluctuations originate from sources at z>8 or t<0.5 Gyr*

*First stars, Santa Fe 2007**	**	**	**	**	**	**A.Kashlinsky*

## 2. Clustering component

- At 3.6 mic the fluctuation is δF~ 0.1 nW/m2/sr at θ≥ 1 arcmin
-  At 20>z>5 angle θ=1` subtends between 2.2 and 3 Mpc
-  Limber equation requires:

- w.

- 4. Concordance CDM cosmology with reasonable biasing then requires
- 	Δ of at most 5-10 % on arcmin scales
- 5. ***Hence, the sources producing these CIB fluctuations should have F******CIB****** >1-2 nW/m******2******/sr***

*First stars, Santa Fe 2007**	**	**	**	**	**	**A.Kashlinsky*

## PSN= ∫ S(m) dFCIB(m) = S(<m>) FCIB(m>mlim)

- PSN= ∫ S(m) dFCIB(m) = S(<m>) FCIB(m>mlim)
- 		   where S(m)=f010-0.4m and dF=S(m)dN(m).
- At 3.6,4.5 mic PSN<(1,2)x10-11 nW2/m4/sr and the level of clustered component of fluctuations indicates F> 1 nW/m2/sr. The fluctuations arise from population with relatively strong clustering component, which has only a weak shot-noise level.

*For F**CIB**~1-2 nW/m**2**/sr, the SN levels indicates the sources *
*contributing to fluctuation must have m**AB**>28-29.*

*First stars, Santa Fe 2007**	**	**	**	**	**	**A.Kashlinsky*

## What is the nature of populations producing the CIB fluctuations?

- t(z=8)=0.6 Gyr; t(z=20)=0.2 Gyr, so Δt< 1Gyr

- This corresponds to (Γ is M/L):

- This requires comoving luminosity density at ~0.6-0.8[(1+z)/6]μm:

- For comparison at z=0:
- L(0.4-0.8μm)~0.1L*
- Ωstars(z=0) ~2x10-3

*First stars, Santa Fe 2007**	**	**	**	**	**	**A.Kashlinsky*

## Resolving sources of CIB

- For the parameters above one expects the sources to have abundance of
- <n> ~ F2CIB/Psn > 8 arcsec-2
- Confusion allows for individual detection when < 1/40-1/25 sources per beam , so these populations are within the confusion of any of the current instruments. (They would be removed if maps are constructed using median filtering).
- To beat the confusion at 5-σ level at 3.6 micron one needs beam of
- ωbeam < 1/25 <n> ~ 5x10-3 (FCIB/2 nw/m2/sr)-2 arcsec-2
- or radius
- Θbeam < 0.02 (FCIB/2 nW/m2/sr) arcsec
***This is (just about) reachable with JWST***

*First stars, Santa Fe 2007**	**	**	**	**	**	**A.Kashlinsky*

## Conclusions

-  Source-subtracted IRAC images contain significant CIB fluctuations.
-  These fluctuations come from populations with significant clustering component but only low levels of the shot-noise component.
-  There are no correlations between source-subtracted IRAC maps and ACS source catalog maps.
-  These imply that the CIB fluctuations originate in populations 1) z>8 (t<0.5 Gyr), 2) S<10 nJy, and 3) M/L << M/L of present day populations.
-  These populations have projected number density of ~5-10 arcsec-2 and are within the confusion noise of the present-day instruments.
-  JWST can resolve them (beam<0.04”).

*First stars, Santa Fe 2007**	**	**	**	**	**	**A.Kashlinsky*