2011A&A...534A..15M


Query : 2011A&A...534A..15M

2011A&A...534A..15M - Astronomy and Astrophysics, volume 534A, 15-15 (2011/10-1)

GOODS-Herschel: a population of 24µm dropout sources at z < 2.

MAGDIS G.E., ELBAZ D., DICKINSON M., HWANG H.S., CHARMANDARIS V., ARMUS L., DADDI E., LE FLOC'H E., AUSSEL H., DANNERBAUER H., RIGOPOULOU D., BUAT V., MORRISON G., MULLANEY J., LUTZ D., SCOTT D., COIA D., POPE A., PANNELLA M., ALTIERI B., BURGARELLA D., BETHERMIN M., DASYRA K., KARTALTEPE J., LEITON R., MAGNELLI B., POPESSO P. and VALTCHANOV I.

Abstract (from CDS):

Using extremely deep PACS 100- and 160µm Herschel data from the GOODS-Herschel program, we identify 21 infrared bright galaxies previously missed in the deepest 24µm surveys performed by Spitzer/MIPS. These MIPS dropouts are predominantly found in two redshift bins, centred at z∼0.4 and ∼1.3. Their S100/S24 flux density ratios are similar to those of local (ultra-) luminous infrared galaxies (LIRGs and ULIRGs), whose silicate absorption features at 18µm (at z∼0.4) and 9.7µm (at z∼1.3) are shifted into the 24µm MIPS band at these redshifts. The high-z sub-sample consists of 11 infrared luminous sources, accounting for ∼2% of the whole GOODS-Herschel sample and putting strong upper limits on the fraction of LIRGs/ULIRGs at 1.0<z<1.7 that are missed by the 24µm surveys. We find that a S100/S24>43 colour cut selects galaxies with a redshift distribution similar to that of the MIPS dropouts and when combined with a second colour cut, S16/S8 > 4, isolates sources at 1.0<z<1.7. We show that these sources have elevated specific star formation rates (sSFR) compared to main sequence galaxies at these redshifts and are likely to be compact starbursts with moderate/strong 9.7µm silicate absorption features in their mid-IR spectra. Herschel data reveal that their infrared luminosities extrapolated from the 24µm flux density are underestimated, on average, by a factor of ∼3. These silicate break galaxies account for 16% (8%) of the ULIRG (LIRG) population in the GOODS fields, indicating a lower limit in their space density of 2.0x10–5/Mpc3. Finally, we provide estimates of the fraction of z<2 MIPS dropout sources as a function of the 24-, 100-, 160-, 250- and 350µm sensitivity limits, and conclude that previous predictions of a population of silicate break galaxies missed by the major 24µm extragalactic surveys have been overestimated.

Abstract Copyright:

Journal keyword(s): galaxies: active - galaxies: evolution - galaxies: formation - galaxies: groups: general - infrared: galaxies

CDS comments: Paragraph 3.2 NGC 22491 is a probable misprint for IRAS 22491-1808, IRAS 17128 a probable misprint for IRAS 17208-0014.

Simbad objects: 14

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Number of rows : 14
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 NGC 1134 IG 02 53 41.3600789046 +13 00 51.205830693   13.2       ~ 107 1
2 NAME GOODS Southern Field reg 03 32 28.0 -27 48 30           ~ 1133 1
3 NGC 2369 GiG 07 16 37.753 -62 20 37.51   13.23   11.56 12.3 ~ 118 0
4 M 82 IG 09 55 52.430 +69 40 46.93 9.61 9.30 8.41     ~ 5470 6
5 NAME COSMOS Field reg 10 00 28.60 +02 12 21.0           ~ 2319 0
6 NGC 3256 IG 10 27 51.284 -43 54 13.55   11.83 11.33 10.62 11.9 ~ 777 2
7 ESO 320-30 H2G 11 53 11.722 -39 07 48.72   13.30   11.86   ~ 160 1
8 NAME SMM J123635+621239 G 12 36 35.20 +62 12 42.4           ~ 22 0
9 NAME GOODS-N Field reg 12 36 55.0 +62 14 15           ~ 979 1
10 NAME Extended Groth Strip reg 14 19 +52.8           ~ 627 0
11 Z 49-57 GiC 15 13 13.1 +07 13 32   15.5       ~ 216 1
12 IC 4553 SyG 15 34 57.22396 +23 30 11.6084   14.76 13.88     ~ 2758 4
13 6dFGS gJ172322.0-001701 LIN 17 23 21.943 -00 17 00.96   15.1       ~ 381 0
14 NAME South America H2G 22 51 49.307 -17 52 23.96   16.97       ~ 295 3

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2021.07.27-20:14:24

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