2014A&A...565A..12P


Query : 2014A&A...565A..12P

2014A&A...565A..12P - Astronomy and Astrophysics, volume 565A, 12-12 (2014/5-1)

Spectroscopy of high-energy BL Lacertae objects with X-shooter on the VLT.

PITA S., GOLDONI P., BOISSON C., LENAIN J.-P., PUNCH M., GERARD L., HAMMER F., KAPER L. and SOL H.

Abstract (from CDS):

BLLac objects detected in γ-rays and, particularly, those detected at very high energies (E>100GeV) by Cherenkov telescopes are extreme sources with most having redshifts lower than 0.2. Their study gives insights on the acceleration mechanisms in play in such systems and is also a valuable tool for putting constraints on the density of extragalactic background light, especially if several objects are detected at different redshifts. As their spectra are dominated by the non-thermal emission of the jet and the spectral features are weak and narrow in the optical domain, measuring their redshift is challenging. However, such a measure is fundamental as it allows a firm determination of the distance and luminosity of the source, and, therefore, a consistent model of its emission. Measurement of the redshift of BLLac objects detected in γ-rays and determination of global properties of their host galaxies is the aim of this study. We observed a sample of eight BLLac objects with the X-shooter spectrograph installed at the ESO Very Large Telescope (VLT) to take advantage of its unprecedented wavelength coverage and its resolution, which is about five times higher than generally used in such studies. We extracted UVB to NIR spectra that we then corrected for telluric absorption and calibrated in flux. We systematically searched for spectral features. When possible, we determined the contribution of the host galaxy to the overall emission. Of the eight BLLac sources, we measured the redshift of five of them and determined lower limits for two through the detection of intervening systems. All seven of these objects have redshifts greater than 0.2. For the remaining one, we estimated, using an indirect method, that its redshift is greater than 0.175. In two cases, we refuted redshift values reported in other publications. Through careful modelling, we determined the magnitude of the host galaxies. In two cases, the detection of emission lines allowed to provide hints on the overall properties of the gas in the host galaxies. Even though we warn that we are dealing with a very small sample, we remark that the redshift determination efficiency of our campaign is higher than for previous campaigns. We argue that it is mainly the result of the comparatively higher resolution of X-shooter.

Abstract Copyright:

Journal keyword(s): galaxies: active - BL Lacertae objects: general - galaxies: distances and redshifts - gamma rays: galaxies

Simbad objects: 10

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Number of rows : 10
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 KUV 00311-1938 BLL 00 33 34.3800569400 -19 21 33.134193864   16.8 16.3 16.6   ~ 113 0
2 WISEA J023734.04-360328.4 BLL 02 37 34.0464247200 -36 03 28.455320844 17.99 17.65 17.63 16.3   ~ 60 0
3 RBS 337 BLL 02 38 32.4803496720 -31 16 58.063079280 16.86 16.81 16.46 16.00   ~ 72 0
4 QSO B0301-243 BLL 03 03 26.5025589984 -24 07 11.426291220   16.55 16.18     ~ 219 1
5 6dFGS gJ044924.7-435009 BLL 04 49 24.6981911928 -43 50 08.960970948 14.95 17.52 15.24 16.27   ~ 165 1
6 ICRF J050534.7+041554 BLL 05 05 34.7693853576 +04 15 54.577536876 18.07 17.80 17.56 16.8   ~ 73 1
7 2FGL J0543.9-5532 BLL 05 43 57.2123766984 -55 32 07.327939200 17.34 17.18 17.09 16.5   ~ 72 0
8 ATO J124.1133-13.1979 BLL 08 16 27.2037492048 -13 11 52.623678156 17.15 17.09 17.00 16.93   ~ 70 0
9 7C 1424+2401 BLL 14 27 00.3917926224 +23 48 00.037510776 14.52 14.34 14.95 14.5   ~ 360 1
10 Feige 110 HS* 23 19 58.3996844256 -05 09 56.171142864 10.360 11.45 11.50 11.970 12.145 sdO8VIIIHe5 632 1

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