2009A&A...505.1007C


Query : 2009A&A...505.1007C

2009A&A...505.1007C - Astronomy and Astrophysics, volume 505, 1007-1016 (2009/10-3)

Uncovering strong MgII absorbing galaxies. Imaging below the Lyman limit.

CHRISTENSEN L., NOTERDAEME P., PETITJEAN P., LEDOUX C. and FYNBO J.P.U.

Abstract (from CDS):

The nature of the galaxies that give rise to absorption lines, such as damped Lyman-α systems (DLAs) or strong MgII lines, in quasar spectra is difficult to investigate in emission. These galaxies can be very faint and located close to the lines of sight of the much brighter background quasars. Taking advantage of the total absorption of the QSO light bluewards of the Lyman limit of two DLAs at z>3.4, we look for the continuum emission from intervening galaxies at z≃2 that are identified via strong metal absorption lines. The MgII absorbers have equivalent width large enough to be potential DLA systems. Deep images are obtained with the FOcal Reducer and Spectrograph (FORS1) on the Very Large Telescope for the fields towards SDSS J110855+120953 and SDSS J140850+020522. These quasars have MgII absorption lines at z=1.87 (Wr(MgII)=2.46Å) and z=1.98 (Wr(MgII)=1.89Å), respectively, and each QSO has two intervening higher redshift DLAs at z>3. The U and R bands of FORS1 lie blue and redwards of the Lyman limit of the background DLAs, allowing us to search for emission from the foreground galaxies directly along the lines of sight to the QSOs. No galaxies are found close to the sight line of the QSO to a point source limit of UAB∼28.0. In both fields, the closest objects lie at an impact parameter of ∼5" corresponding to ∼40kpc in projection at z=2, and have typical colours of star forming galaxies at that redshift. However, the currently available data do not allow us to confirm if the galaxies lie at the same redshifts as the absorption systems. A more extended structure is visible in the SDSS J14085+020522 field at an impact parameter of 0.8" or 7kpc. If these objects are at z≃2 their luminosities are 0.03-0.04L* in both fields. The star formation rates estimated from the UV flux are 0.5-0.6M/yr, while the SFRs are half these values if the U band flux is due to Lyα emission alone. The non-detection of galaxies near to the line of sight is most likely explained by low metallicities and luminosities of the MgII galaxies. Alternatively, the MgII clouds are part of extended halos or in outflows from low-metallicity galaxies.

Abstract Copyright:

Journal keyword(s): cosmology: observations - galaxies: high-redshift - quasars: absorption lines - quasars: individual: SDSS J110855.46+120953.3 - quasars: individual: SDSS J140850.91+020522.7

Nomenclature: Table 1: [CNP2009] QHHMM abs N.NNNN N=4. Table 2: [CNP2009] QHHMM Na N=5+8.

Status at CDS : All or part of tables of objects will not be ingested in SIMBAD.

Simbad objects: 18

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Number of rows : 18
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 4C -02.19 QSO 05 01 12.80988538 -01 59 14.2564557   19.1 18.4 19.04   ~ 555 1
2 RL 149 HS* 07 24 14.3741784768 -00 33 04.165016904 12.958 13.737 13.866 13.906 13.974 sdB 111 0
3 [CNP2009] Q1108 3a G 11 08 55.0 +12 09 50 22.66     22.23   ~ 1 0
4 [CNP2009] Q1108 2a G 11 08 55.2 +12 09 56 27.06         ~ 1 0
5 SDSS J110855.46+120953.3 QSO 11 08 55.4652728904 +12 09 53.344550916   20.81 19.72     ~ 43 0
6 [CNP2009] Q1108 1a G 11 08 55.5 +12 10 02 25.83     25.41   ~ 1 0
7 [CNP2009] Q1108 4a G 11 08 55.7 +12 09 49 25.88         ~ 1 0
8 [CNP2009] Q1108 5a G 11 08 55.8 +12 09 48 26.75         ~ 1 0
9 [CNP2009] Q1408 7b G 14 08 50.3 +02 05 21 26.73     24.88   ~ 1 0
10 [CNP2009] Q1408 6b G 14 08 50.5 +02 05 15 26.03     26.41   ~ 1 0
11 [CNP2009] Q1408 5b G 14 08 50.7 +02 05 15 25.53     24.79   ~ 1 0
12 [CNP2009] Q1408 2b G 14 08 50.8 +02 05 17 24.64     24.81   ~ 1 0
13 [CNP2009] Q1408 1b G 14 08 50.9 +02 05 29       25.82   ~ 1 0
14 QSO J1408+0205 QSO 14 08 50.9138577456 +02 05 22.680293784   20.55 19.75     ~ 35 0
15 [CNP2009] Q1408 8b G 14 08 51.0 +02 05 22 26.92         ~ 1 0
16 [CNP2009] Q1408 3b G 14 08 51.4 +02 05 18 25.75     25.64   ~ 1 0
17 [CNP2009] Q1408 4b G 14 08 51.5 +02 05 16 25.55     22.25   ~ 1 0
18 KODIAQ J223235+024755 QSO 22 32 35.2154152488 +02 47 55.814764596   18.387 18.038     ~ 92 0

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2023.01.31-08:15:44

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