2016A&A...585A..48G


C.D.S. - SIMBAD4 rel 1.7 - 2021.01.22CET02:40:52

2016A&A...585A..48G - Astronomy and Astrophysics, volume 585A, 48-48 (2016/1-1)

The Lyman continuum escape fraction of galaxies at z = 3.3 in the VUDS-LBC/COSMOS field.

GRAZIAN A., GIALLONGO E., GERBASI R., FIORE F., FONTANA A., LE FEVRE O., PENTERICCI L., VANZELLA E., ZAMORANI G., CASSATA P., GARILLI B., LE BRUN V., MACCAGNI D., TASCA L.A.M., THOMAS R., ZUCCA E., AMORIN R., BARDELLI S., CASSARA L.P., CASTELLANO M., CIMATTI A., CUCCIATI O., DURKALEC A., GIAVALISCO M., HATHI N.P., ILBERT O., LEMAUX B.C., PALTANI S., RIBEIRO B., SCHAERER D., SCODEGGIO M., SOMMARIVA V., TALIA M., TRESSE L., VERGANI D., BONCHI A., BOUTSIA K., CAPAK P., CHARLOT S., CONTINI T., DE LA TORRE S., DUNLOP J., FOTOPOULOU S., GUAITA L., KOEKEMOER A., LOPEZ-SANJUAN C., MELLIER Y., MERLIN E., PARIS D., PFORR J., PILO S., SANTINI P., SCOVILLE N., TANIGUCHI Y. and WANG P.W.

Abstract (from CDS):

The ionizing Lyman continuum flux escaping from high-redshift galaxies into the intergalactic medium is a fundamental quantity to understand the physical processes involved in the reionization epoch. However, from an observational point of view, direct detections of HI ionizing photons at high redshifts are feasible for galaxies mainly in the interval z∼3-4. We have investigated a sample of star-forming galaxies at z∼3.3 to search for possible detections of Lyman continuum ionizing photons escaping from galaxy halos. We used deep ultraviolet (UV) imaging in the COSMOS field, obtained with the prime focus camera LBC at the LBT telescope, along with a catalogue of spectroscopic redshifts obtained by the VIMOS Ultra Deep Survey (VUDS) to build a sample of 45 galaxies at z∼3.3 with L>0.5L*. We obtained deep LBC images of galaxies with spectroscopic redshifts in the interval 3.27<z<3.40 both in the R- and deep U-bands (magnitude limit U∼29.7 at S/N=1). At these redshifts, the R-band samples the non-ionizing 1500Å rest-frame luminosity and the U-band samples the rest-frame spectral region just short-ward of the Lyman edge at 912Å. Their flux ratio is related to the ionizing escape fraction after statistical removal of the absorption by the intergalactic medium along the line of sight. A subsample of ten galaxies apparently shows escape fractions >28%, but a detailed analysis of their properties reveals that, with the exception of two marginal detections (S/N∼2) in the U-band, all the other eight galaxies are most likely contaminated by the UV flux of low-redshift interlopers located close (in angular position) to the high-z targets. The average escape fraction derived from the stacking of the cleaned sample was constrained to frelesc<2%. The implied hydrogen photoionization rate is a factor two lower than that needed to keep the intergalactic medium ionized at z∼3, as observed in the Lyman-α forest of high-z quasar spectra or by the proximity effect. These results support a scenario where high redshift, relatively bright (L≥0.5L*) star-forming galaxies alone are unable to sustain the level of ionization observed in the cosmic intergalactic medium at z∼3. Star-forming galaxies at higher redshift and at fainter luminosities (L≪L*) can only be major contributors to the reionization of the Universe if their physical properties are subject to rapid changes from z∼3 to z∼6-10. Alternatively, ionizing sources could be discovered looking for fainter sources among the active galactic nuclei population at high redshift.

Abstract Copyright:

Journal keyword(s): galaxies: distances and redshifts - galaxies: evolution - galaxies: high-redshift - galaxies: photometry

Nomenclature: Table 1: [BGG2011b] NNNNN N=34 among (Nos 1723-74113) added.

Simbad objects: 51

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Number of rows : 51

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 NAME GOODS Southern Field reg 03 32 28.0 -27 48 30           ~ 1102 1
2 NAME Extended Chandra Deep Field South reg 03 32 30.0 -27 48 20           ~ 639 0
3 SAS-LBG Q0933-M6 G 09 33 18.900146 +28 43 08.67417       25.13   ~ 3 0
4 SAS-LBG Q0933-D26 G 09 33 25.081787 +28 48 24.88129       24.88   ~ 3 0
5 SAS-LBG Q0933-M13 G 09 33 26.429443 +28 44 02.70630       25.59   ~ 3 0
6 SAS-LBG Q0933-MD47 G 09 33 31.790772 +28 45 10.82840       24.91   ~ 3 0
7 UVISTADR1 J095906.91+021346.0 G 09 59 06.91 +02 13 45.7   25.57 24.52 24.65 24.36 ~ 4 0
8 COSMOS 1715744 G 09 59 15.66 +02 08 17.2 27.58 26.693 25.38 24.98 24.61 ~ 2 0
9 [BGG2011b] 4890 G 09 59 17.838135 +02 00 33.51860       25.24   ~ 1 0
10 COSMOS 2077128 G 09 59 20.18 +02 18 02.9   25.81 24.58 24.64 24.59 ~ 3 0
11 UVISTADR1 J095920.18+022500.0 G 09 59 20.18 +02 25 00.3 26.95 25.42 24.54 24.59 24.44 ~ 5 0
12 COSMOS 2068193 G 09 59 22.42 +02 20 24.3 28.47 26.080 25.366 25.02   ~ 1 0
13 COSMOS 2060480 G 09 59 23.27 +02 22 23.0 26.81 25.01 24.04 23.70 23.44 ~ 4 0
14 COSMOS 2071442 G 09 59 23.54 +02 19 30.7   26.828 26.228 25.23 24.89 ~ 3 0
15 COSMOS 2077672 G 09 59 24.82 +02 17 54.2   26.764 25.19 24.84 24.25 ~ 3 0
16 UVISTADR1 J095925.71+021612.4 G 09 59 25.71 +02 16 12.4 27.55 26.37 25.52 25.22 25.15 ~ 3 0
17 COSMOS 2066116 G 09 59 28.84 +02 20 56.6   25.400 24.521 23.90   ~ 2 0
18 COSMOS 1680921 G 09 59 30.53 +02 17 02.0 25.29 25.23 24.54 24.16 23.71 ~ 3 0
19 COSMOS 1680234 G 09 59 31.98 +02 17 12.2   26.373 25.220 24.71   ~ 2 0
20 COSMOS2015 642746 AGN 09 59 32.66 +02 16 33.4 27.42 24.83 23.68 23.57 23.44 ~ 12 0
21 COSMOS 1714056 G 09 59 33.24 +02 08 41.5 27.26 26.208 25.37 24.91 24.33 ~ 3 0
22 UVISTADR1 J095934.11+022452.9 G 09 59 34.10 +02 24 53.1 27.54 25.73 24.56 24.52 24.42 ~ 5 0
23 COSMOS 1652436 G 09 59 39.07 +02 14 12.4 27.76 26.248 25.17 24.75 24.43 ~ 3 0
24 COSMOS 2019409 G 09 59 40.19 +02 22 43.2   25.84 24.88 24.62 24.57 ~ 3 0
25 COSMOS 1279972 G 09 59 44.23 +02 06 08.7   26.594 25.61 25.33 24.95 ~ 3 0
26 COSMOS 2017222 G 09 59 45.34 +02 23 18.1 27.87 25.88 24.82 24.64 24.29 ~ 3 0
27 COSMOS 1284607 G 09 59 45.64 +02 04 56.8 27.86 25.56 24.53 24.39 24.30 ~ 3 0
28 COSMOS 1665094 G 09 59 48.54 +02 10 58.0 28.36 26.093 25.584 25.19   ~ 1 0
29 COSMOS 1284921 G 09 59 50.67 +02 04 52.1   26.04 24.98 24.77 24.43 ~ 3 0
30 COSMOS 2022490 G 09 59 51.11 +02 21 49.7   26.08 24.82 24.53 24.46 ~ 3 0
31 COSMOS 1277895 G 09 59 53.86 +02 06 42.7 27.88 25.77 24.71 24.49 24.28 ~ 3 0
32 COSMOS 1676475 G 09 59 54.91 +02 08 08.0   26.09 24.95 24.83 24.66 ~ 3 0
33 [BGG2011b] 52336 G 09 59 55.264893 +02 24 20.56538 27.06     24.85   ~ 1 0
34 COSMOS 2028588 G 09 59 55.93 +02 20 19.2   26.00 25.12 24.92 24.70 ~ 3 0
35 COSMOS 1641312 G 09 59 58.54 +02 17 05.9 26.88 25.02 24.16 24.19 24.12 ~ 3 0
36 [BGG2011b] 16669 G 09 59 58.791504 +02 04 49.18934 26.06     24.39   ~ 1 0
37 VUDS 511265048 G 10 00 12.45 +02 19 57.3   25.749 24.908 24.19   ~ 2 0
38 COSMOS2015 733018 G 10 00 15.68 +02 24 42.6   26.21 24.85 24.76 24.51 ~ 5 0
39 COSMOS 1635100 G 10 00 23.15 +02 08 45.6 27.78 25.871 25.243 24.91   ~ 1 0
40 UVISTADR1 J100025.58+020240.1 G 10 00 25.59 +02 02 40.2   26.35 25.19 25.07 24.91 ~ 2 0
41 NAME COSMOS Field reg 10 00 28.60 +02 12 21.0           ~ 2177 0
42 COSMOS 1627662 G 10 00 32.91 +02 10 29.0   26.260 25.697 25.44   ~ 1 0
43 COSMOS 1997141 EmG 10 00 33.32 +02 18 25.0 27.67 25.70 24.52 24.53 24.42 ~ 8 0
44 UVISTADR1 J100033.84+021422.7 G 10 00 33.84 +02 14 22.5   26.40 25.28 25.18 25.11 ~ 5 0
45 COSMOS 1209190 G 10 01 19.27 +02 04 20.2 25.86 24.95 23.85 23.52 23.19 ~ 4 0
46 UVISTADR1 J100139.58+020932.3 G 10 01 39.58 +02 09 32.6 26.96 24.90 23.76 23.54 23.31 ~ 4 0
47 COSMOS 1907859 G 10 01 47.29 +02 20 51.1   25.764   23.63   ~ 3 0
48 NAME Extended Groth Strip reg 14 19 +52.8           ~ 604 0
49 QSO J1551+1911 QSO 15 51 52.4690044121 +19 11 04.016404109           ~ 52 0
50 [BGG2011b] 17175 G 16 25 52.602539 +26 53 32.54654       24.69   ~ 2 0
51 SSA 22 reg 22 17 34.7 +00 15 07           ~ 269 0

    Equat.    Gal    SGal    Ecl

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2021.01.22-02:40:52

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