2004A&A...414....7G


Query : 2004A&A...414....7G

2004A&A...414....7G - Astronomy and Astrophysics, volume 414, 7-16 (2004/1-4)

Evidence for a significant Blazar contamination in CMB anisotropy maps.

GIOMMI P. and COLAFRANCESCO S.

Abstract (from CDS):

The analysis of the recent WMAP source catalog shows that the vast majority of bright foreground extragalactic sources detected in CMB maps are Blazars. In this paper we calculate the contamination of CMB anisotropy maps by this type of flat-spectrum, strongly variable and polarized extragalactic radio sources using up-to-date results from recent deep multi-frequency surveys. From a careful archive search and from multi-frequency catalog cross-correlations we found that more than 50 known Blazars (or Blazar candidates) expected to be above the sensitivity limit of the BOOMERANG experiment are included in the 90/150GHz BOOMERANG anisotropy maps, a factor >15 larger than previously reported. Using a recent derivation of the Blazar radio logN-logS we show that Blazars, whose counts continue to grow steeply down to faint fluxes, can sensitively affect CMB fluctuation maps with even moderate resolution and sensitivity. We calculate specifically that these sources induce an average sky brightness of 0.4Jy/deg2, corresponding to an average temperature of ≃4-8µK. Moreover, we find that the associated level of fluctuations is of the order of Cl,Blazar=2x10–2µK2 sr at 41 GHz and Cl,Blazar=1x10–3µK2 sr at 94GHz. Taking into account both Blazar variability, causing the detection of a number of weak sources that rise above the detector sensitivity during flares in long-exposure satellite experiments, and the many steep-spectrum radio sources that flatten at high frequencies, as well as the contribution of radio-galaxies, we find that the level of residual fluctuation due to discrete extragalactic foreground sources could be factor of ∼2-3 higher than the above estimate. We show that the Blazar induced fluctuations contaminate the CMB spectrum at the level of ≃30-90% at l=500 and 80-100% at l=800, and thus they cannot be neglected in the derivation of the primordial CMB fluctuation spectrum. Since Blazars are bright sources because they point their jets towards the observer, at faint fluxes a more abundant population of less-aligned sources is likely to increase the contamination of future high-resolution high-sensitivity CMB maps. Careful cleaning for Blazar contamination of CMB maps is therefore necessary before firm conclusions about weak features, like secondary high-l peaks of the CMB power spectrum or very weak signals like CMB polarization measurements, can be achieved.

Abstract Copyright:

Journal keyword(s): cosmology: observations - cosmic microwave background - galaxies: active

Simbad objects: 53

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Number of rows : 53
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024
#notes
1 QSO B0252-549 QSO 02 53 29.1803201880 -54 41 51.437517216   17.65 19.3 16.79   ~ 128 1
2 QSO B0257-510 QSO 02 58 38.74798 -50 52 04.3848     20.0 21.8   ~ 22 1
3 QSO B0308-611 QSO 03 09 56.09914475 -60 58 39.0564095   19.00 18.5 18.18   ~ 136 1
4 ACT-S J031206-554135 QSO 03 12 07.2134820720 -55 41 34.821112632       17.99   ~ 18 0
5 PKS 0317-570 Rad 03 18 58.6 -56 50 35           ~ 1 0
6 PMN J0321-3711 Rad 03 21 23.30 -37 11 34.0           ~ 4 0
7 6dFGS gJ034205.4-370322 SyG 03 42 05.3 -37 03 21   18.84 18.6 17.65   ~ 44 1
8 QSO J0403-3605 Bla 04 03 53.74990003 -36 05 01.9131880   17.04 17.17 16.67   ~ 283 1
9 QSO B0405-385 QSO 04 06 59.03533781 -38 26 28.0423651   19.55 18.0     ~ 232 2
10 QSO B0410-519 QSO 04 11 37.1499317880 -51 49 23.348533512     18.0     ~ 21 0
11 IVS B0417-302 QSO 04 19 47.2049500608 -30 10 23.852974800   17.7   17.3   ~ 16 0
12 QSO J0422-3844 BLL 04 22 14.7829521792 -38 44 52.826059032   17.70 16.92 16.3   ~ 201 1
13 1WGA J0424.6-3849 QSO 04 24.6 -38 49           ~ 2 0
14 QSO B0422-380 QSO 04 24 42.24370316 -37 56 20.7843026   17.96 18.08 18.03   ~ 100 1
15 2MASX J04285086-3805503 BLL 04 28 50.8440888600 -38 05 50.439578784     18.90 15.6   ~ 13 0
16 1RXS J043208.7-350651 X 04 32 08.7 -35 06 51           ~ 3 0
17 QSO B0432-606 QSO 04 33 34.1084892864 -60 30 13.769648496     18.0     ~ 51 1
18 QSO B0435-300 BLL 04 37 36.5686975680 -29 54 04.117331088     17.5     ~ 43 0
19 QSO B0438-43 QSO 04 40 17.17997576 -43 33 08.6043290   19.31 19.5 18.2   ~ 285 2
20 PKS 0439-331 Rad 04 41 36.3 -33 00 50           ~ 1 0
21 QSO B0443-387 QSO 04 45 10.6322367936 -38 38 35.397508020   18.25 17.5 16.77   ~ 17 1
22 QSO B0448-392 QSO 04 49 42.2546470224 -39 11 09.470347512   16.70 16.46 16.28   ~ 74 1
23 QSO B0450-469 Bla 04 51 53.3468902656 -46 53 19.894609392   19.0 19.0     ~ 30 1
24 QSO B0454-463 QSO 04 55 50.77248730 -46 15 58.6797903   17.89 17.4 16.87   ~ 215 1
25 QSO J0506-6109 QSO 05 06 43.98874900 -61 09 40.9939787   17.16 16.85 16.9   ~ 178 2
26 NGC 1808 Sy2 05 07 42.343 -37 30 46.98 11.05 10.80 9.94 9.36 10.2 ~ 717 3
27 PMN J0510-3533 Rad 05 10 53.2 -35 33 18           ~ 4 1
28 LEDA 2824273 Sy2 05 12 47.23 -48 24 16.4   19       ~ 29 1
29 PKS J0514-4903 rG 05 14 39.494 -49 03 29.06   15.93 17.0     ~ 20 1
30 ICRF J051545.2-455643 Sy1 05 15 45.2501347656 -45 56 43.198786536   18.18 17.5 17.31   ~ 111 1
31 NAME Pic A Sy1 05 19 49.7229323856 -45 46 43.852662732   15.73 15.77 14.85   ~ 656 1
32 ESO 362-21 Sy1 05 22 57.98464178 -36 27 30.8512953   15.26 14.62 14.48   ~ 825 2
33 QSO J0525-3343 QSO 05 25 06.1749810960 -33 43 05.643939828     18.50 18.5   ~ 57 1
34 PMN J0529-3555 Rad 05 29 37 -35 55.4       19.20   ~ 7 0
35 1RXS J053132.1-353331 X 05 31 32.1 -35 33 31           ~ 1 0
36 [VV98] J053417.5-374726 QSO 05 34 17.48653637 -37 47 25.5945656   21.4   19.79   ~ 32 1
37 QSO J0536-3401 QSO 05 36 28.43236164 -34 01 11.4684065   18.00 18.30     ~ 51 1
38 QSO B0537-441 BLL 05 38 50.36155950 -44 05 08.9390233   15.77 16.48 16   ~ 877 2
39 ICRF J054045.8-541822 QSO 05 40 45.8480957784 -54 18 22.095295668   18.49   17.32   ~ 73 0
40 1RXS J054329.1-395638 X 05 43 29.1 -39 56 38           ~ 1 0
41 PKS J0545-4756 Rad 05 45 10.8 -47 56 40           ~ 7 1
42 QSO B0549-575 QSO 05 50 09.58019747 -57 32 24.3965358   20.26 19.5 18.81   ~ 48 1
43 QSO B0548-322 BLL 05 50 40.5705144672 -32 16 16.484718648   16.07 15.5     ~ 403 1
44 ESO 424-27 rG 05 50 49.8216734616 -31 44 26.456438832   14.99   13.49   ~ 31 1
45 PKS 0555-374 Rad 05 57 15.1 -37 29 15           ~ 1 0
46 QSO B0602-319 QSO 06 04 14.5249715184 -31 55 58.492829784     18.3     ~ 55 1
47 [VV96] J060607.2-344740 BLL 06 06 07.3533612912 -34 47 39.257651760   18.6 18.6     ~ 10 1
48 QSO B0607-605 QSO 06 07 55.0870713696 -60 31 51.994639992     18.2     ~ 19 1
49 2MASS J06084056-3041339 AGN 06 08 40.5697663104 -30 41 33.982927800   17.97   16.65   ~ 11 0
50 QSO B0610-316 QSO 06 12 29.6643085104 -31 38 58.194619368     18.5 17.9   ~ 33 1
51 ICRF J061519.2-311721 BLL 06 15 19.2116728752 -31 17 21.575535144     17.0 18.8   ~ 22 1
52 [OKM2018] SWIFT J0632.1-5404 Sy1 06 32 01.1618672256 -54 04 57.471904236   18.15 18.7 17.06   ~ 32 0
53 [VV98] J064813.4-434715 QSO 06 48 13.4237077968 -43 47 15.498800952     18.30     ~ 16 0

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