a) summary iso, spitzer & scuba counts are used to constrain models of extragalactic...

Extragalactic Confusion LimitsExtragalactic Confusion Limitsin Herschel Key Programsin Herschel Key Programs

Mattia Vaccari & Alberto Franceschini & Giulia Rodighiero & Stefano Berta Mattia Vaccari & Alberto Franceschini & Giulia Rodighiero & Stefano Berta Department of Astronomy - University of PadovaDepartment of Astronomy - University of Padova

A) SummaryA) Summary ISO, Spitzer & SCUBA counts are used to constrain models of extragalactic populationsISO, Spitzer & SCUBA counts are used to constrain models of extragalactic populations Extragalactic confusion in Herschel bands is estimated using 2 complementary criteriaExtragalactic confusion in Herschel bands is estimated using 2 complementary criteria The two approaches respectively measure cell-to-cell fluctuations due to unresolved The two approaches respectively measure cell-to-cell fluctuations due to unresolved sources and set a maximum number density for resolved sourcessources and set a maximum number density for resolved sources These two methods provide results which are in good agreement for all Herschel bandsThese two methods provide results which are in good agreement for all Herschel bands Currently envisaged sensitivities for Herschel KP surveys are compared with our Currently envisaged sensitivities for Herschel KP surveys are compared with our predictions and opportunities for Herschel OT extragalactic KP surveys are outlinedpredictions and opportunities for Herschel OT extragalactic KP surveys are outlined

Mattia VaccariMattia Vaccarimattia@mattiavaccari.netwww.mattiavaccari.net

E) “Fluctuations” vs. “Counts” Confusion LimitsE) “Fluctuations” vs. “Counts” Confusion Limits 3 3 “Fluctuations” are very close to “Counts” 10 bps for PACS but nearer to 20 “Fluctuations” are very close to “Counts” 10 bps for PACS but nearer to 20 bps for SPIRE, due to different count slopes at and fainter than 10/20 bps levelsbps for SPIRE, due to different count slopes at and fainter than 10/20 bps levels The availability of multi-The availability of multi- data (e.g. MIPS 24 data (e.g. MIPS 24 m for PACS, PACS & SCUBA2 for m for PACS, PACS & SCUBA2 for SPIRE, etc) will be invaluable in linking various wavelength regimes and accurately SPIRE, etc) will be invaluable in linking various wavelength regimes and accurately pin-pointing sources in order to reach down to 10 bps levels in all Herschel bands.pin-pointing sources in order to reach down to 10 bps levels in all Herschel bands.See posters by Franceschini on H-COSMOS and by Dunne & Dunlop on H-SCLS See posters by Franceschini on H-COSMOS and by Dunne & Dunlop on H-SCLS

B) Confusion at Long Wavelengths with HerschelB) Confusion at Long Wavelengths with Herschel Confusion sets a major limit to the sensitivity of long-Confusion sets a major limit to the sensitivity of long- extragalactic surveys extragalactic surveys As IRAS first dramatically showed, the FIR/sub-mm sky is very densely populatedAs IRAS first dramatically showed, the FIR/sub-mm sky is very densely populated ISO & Spitzer & SCUBA confirmed this view providing a wealth of additional dataISO & Spitzer & SCUBA confirmed this view providing a wealth of additional data Great care must be taken in taking stock of current knowledge in order to predict Great care must be taken in taking stock of current knowledge in order to predict Herschel confusion limits and thus allow a timely planning of GT & OT KP observationsHerschel confusion limits and thus allow a timely planning of GT & OT KP observations

D) Measuring Confusion through “Fluctuations” & “Counts”D) Measuring Confusion through “Fluctuations” & “Counts” ““Fluctuations” measure fluctuations in the background due to unresolved sources Fluctuations” measure fluctuations in the background due to unresolved sources [Franceschini et al. 1989 (ApJ, 344) ] and set “confusion” at the [Franceschini et al. 1989 (ApJ, 344) ] and set “confusion” at the 3 3 fluctuation level fluctuation level “ “Counts” measure source counts and set “confusion” where a maximum number of Counts” measure source counts and set “confusion” where a maximum number of sources per beam, or rather a minimum number of beams per source (bps), is reached sources per beam, or rather a minimum number of beams per source (bps), is reached [Franceschini et al. 2001 (A&A, 378)][Franceschini et al. 2001 (A&A, 378)] Roughly speaking, while “Fluctuations” follow the trend of counts fainter than the Roughly speaking, while “Fluctuations” follow the trend of counts fainter than the confusion limit, “Counts” follow the trend at brighter fluxes than that. The degree of confusion limit, “Counts” follow the trend at brighter fluxes than that. The degree of consistency between the two depends on the slope of counts at and near this flux limit.consistency between the two depends on the slope of counts at and near this flux limit.

F) Recommendations for Herschel GT & OT KP PlanningF) Recommendations for Herschel GT & OT KP Planning From a confusion point of view, From a confusion point of view, target sensitivities envisaged in Herschel GT target sensitivities envisaged in Herschel GT KP surveys appear to be realistic when modeling ISO & Spitzer & SCUBA results.KP surveys appear to be realistic when modeling ISO & Spitzer & SCUBA results. Opportunities exist to go deeper (see posters by Franceschini on H-COSMOS Opportunities exist to go deeper (see posters by Franceschini on H-COSMOS and by Dunne & Dunlop on H-SCLS) and wider (see posters by De Zotti on SPIRE and by Dunne & Dunlop on H-SCLS) and wider (see posters by De Zotti on SPIRE LAS and by Serjeant on H-SASSy) over medium- and large-size areas.LAS and by Serjeant on H-SASSy) over medium- and large-size areas. In particular, judging from Spitzer results, reaching the 3 In particular, judging from Spitzer results, reaching the 3 ~ 10 bps levels in all ~ 10 bps levels in all PACS & SPIRE bands over larger areas than planned in GT KP surveys appears to PACS & SPIRE bands over larger areas than planned in GT KP surveys appears to be feasible and thus somehow mandatory in order to fulfill Herschel’s potential for be feasible and thus somehow mandatory in order to fulfill Herschel’s potential for extragalactic surveys. Such deep OT KP surveys should be undertaken over sky extragalactic surveys. Such deep OT KP surveys should be undertaken over sky areas where deep Spitzer MIPS 24 areas where deep Spitzer MIPS 24 m and/or SCUBA2 coverage is or will soon be m and/or SCUBA2 coverage is or will soon be available, e.g. within the most popular “Cosmic Windows”.available, e.g. within the most popular “Cosmic Windows”. Survey-like ultra-deep exploratory efforts should be undertaken at a relatively Survey-like ultra-deep exploratory efforts should be undertaken at a relatively early time during Herschel operations in order to determine actual confusion levels early time during Herschel operations in order to determine actual confusion levels and test deconvolution techniques in a timely manner, thus ensuring to make the and test deconvolution techniques in a timely manner, thus ensuring to make the most of Herschel’s 3-year life span.most of Herschel’s 3-year life span.

ChannelChannel PACS1PACS1 PACS2PACS2 PACS3PACS3 SPIRE1SPIRE1 SPIRE2SPIRE2 SPIRE3 SPIRE3 mm 7070 110110 170170 250250 350350 500500

Beam FWHMBeam FWHM 4 .74”4 .74” 6.96”6.96” 10.76”10.76” 17.1”17.1” 24.4”24.4” 34.6”34.6”3 3 [mJy] [mJy] 0.070470.07047 1.0021.002 7.4847.484 18.1218.12 22.5522.55 20.1920.19

10 bps [mJy]10 bps [mJy] 0.11000.1100 1.2631.263 7.0907.090 14.0014.00 15.2315.23 13.2313.2320 bps [mJy]20 bps [mJy] 0.30290.3029 2.7462.746 11.8211.82 20.4920.49 21.6521.65 18.3118.3130 bps [mJy]30 bps [mJy] 0.48870.4887 4.0344.034 15.2315.23 25.4025.40 26.3426.34 21.4921.4940 bps [mJy]40 bps [mJy] 0.66560.6656 5.1105.110 18.1218.12 29.1829.18 29.9329.93 24.0924.0950 bps [mJy]50 bps [mJy] 0.83500.8350 6.1076.107 20.4520.45 32.4732.47 33.0533.05 26.1826.18

C) Modelling ISO, Spitzer & SCUBA ObservationsC) Modelling ISO, Spitzer & SCUBA Observations Models by Franceschini et al. 2001 (A&A, 378) were updated to account for intervened Models by Franceschini et al. 2001 (A&A, 378) were updated to account for intervened reanalyses of ISO 15 reanalyses of ISO 15 m data and results from Spitzer MIPS and SCUBA observationsm data and results from Spitzer MIPS and SCUBA observations Models describe available observables (number counts, z-distributions, L-functions, Models describe available observables (number counts, z-distributions, L-functions, integrated CIRB levels…), in terms of four populationsintegrated CIRB levels…), in terms of four populations

slowly or non-evolving disk galaxies [slowly or non-evolving disk galaxies [blueblue dotted lines] dotted lines] type-1 AGNs evolving as shown by UV and X-ray selected quasars & Seyfertstype-1 AGNs evolving as shown by UV and X-ray selected quasars & Seyferts [[greengreen long-short dashed lines] long-short dashed lines] moderate-luminosity starbursts with peak emission at z ~ 1 [moderate-luminosity starbursts with peak emission at z ~ 1 [cyancyan dot-dashed lines] dot-dashed lines] ultra-luminous starbursts with peak evolution between z = 2 and z = 4 ultra-luminous starbursts with peak evolution between z = 2 and z = 4 [[redred long dashed lines]long dashed lines]

NameName AreaArea FieldField PACS PACS TimeTime

SPIRE SPIRE TimeTime 7070 110110 170170 250250 350350 500500

-- deg^2deg^2 -- hrhr hrhr mJymJy mJymJy mJymJy mJymJy mJymJy mJymJy

ClustersClusters -- -- 8080 100100 -- -- -- -- -- --

Level 1Level 1 0.040.04 GOODS-SGOODS-S 230230 1010++3030 1.01.0 1.01.0 1.01.0 3.33.3 4.04.0 4.64.6

Level 2Level 2 0.040.04 GOODS-NGOODS-N 2727 1010 2.02.0 2.82.8 3.03.0 6.76.7 8.18.1 9.29.2

Level 3Level 3 0.250.25 GOODS-SGOODS-S 3434 2525 2.22.2 6.26.2 6.76.7 10.510.5 12.712.7 14.514.5

0.250.25 Groth StripGroth Strip 3434 2525 2.22.2 6.26.2 6.76.7 10.510.5 12.712.7 14.514.5

0.250.25 LockmanLockman 3434 2525 2.22.2 6.26.2 6.76.7 10.510.5 12.712.7 14.514.5

Level 4Level 4 22 COSMOSCOSMOS 110110 5050 6.06.0 9.89.8 10.510.5 21.121.1 25.525.5 29.129.1

22 XMM-LSSXMM-LSS 110110 5050 1818 9.89.8 10.510.5 21.121.1 25.525.5 29.129.1

Level 5Level 5 1010 SpitzerSpitzer 185185 200200 1818 16.916.9 18.018.0 23.623.6 28.528.5 32.532.5

Level 6Level 6 5050 SpitzerSpitzer -- 150150 1818 -- 120120 6161 7474 8484

Time (hr) : Time (hr) : PACS (659)PACS (659) SPIRE (850) SPIRE (850) Harwit (10)Harwit (10) (Spitzer Depths)(Spitzer Depths)

Herschel Extragalactic GT Survey Wedding CakeHerschel Extragalactic GT Survey Wedding Cake

Confusion sets in at a flux determined Confusion sets in at a flux determined by the Beam FWHM line (right)by the Beam FWHM line (right)

and the 10 bps line (below)and the 10 bps line (below)

SPIRE 350SPIRE 350PACS 170PACS 170PACS 70PACS 70

(See C) for Legenda)(See C) for Legenda)

Integral CountsIntegral Counts

Rodighiero et al. 2006 (MNRAS, 371) Rodighiero et al. 2006 (MNRAS, 371) showed that using conventional showed that using conventional

deconvolution techniques one can deconvolution techniques one can use IRAC 3.6 use IRAC 3.6 m positions to detect m positions to detect MIPS 24 MIPS 24 m sources down to 3 m sources down to 3 ~ ~ 10 bps levels, thus “extrapolating” 10 bps levels, thus “extrapolating” by nearly a decade in by nearly a decade in , as in e.g., as in e.g.

MIPS 24 MIPS 24 m vs SPIRE 250 m vs SPIRE 250 mm

MIPS 24 MIPS 24 mm MIPS 70 MIPS 70 mm MIPS 160 MIPS 160 mm

SCUBA 850 SCUBA 850 mm

z-distributionz-distribution

MIPS 24 MIPS 24 mm

(See C) for Legenda)(See C) for Legenda)

……fitting additional fitting additional observables into observables into modeling picture modeling picture

and applying and applying techniques to other techniques to other

instruments, e.g. instruments, e.g. Akari & Planck & Akari & Planck & SPICA & FIRM.SPICA & FIRM.

Public web page is Public web page is also in the works!also in the works!

An Herschel Survey of Surveys (SOS)An Herschel Survey of Surveys (SOS)www.mattiavaccari.net/herschel/sos

3 3 ~ 10 bps ~ 10 bps

3 3 ~ 20 bps ~ 20 bps 10 bps10 bps

20 bps 20 bps

From a confusion From a confusion point of view, rich point of view, rich opportunities exist opportunities exist

to extend GT KP to extend GT KP mid- & large-area mid- & large-area planned surveysplanned surveys

(~ 1 deg(~ 1 deg2 2 or larger) or larger) to deeper levels, to deeper levels,

and particularly so and particularly so on the PACS sideon the PACS side

Opp. AreaOpp. Area

Opp. AreaOpp. Area

What extragalactic OT KP surveys can we ask of Herschel?What extragalactic OT KP surveys can we ask of Herschel?