J/ApJ/861/130 BL Lac objects GTC low resolution spectroscopy (Landoni+, 2018)
High-redshift BL Lac objects: spectroscopy of candidates.
Landoni M., Paiano S., Falomo R., Scarpa R., Treves A.
<Astrophys. J., 861, 130 (2018)>
=2018ApJ...861..130L 2018ApJ...861..130L
ADC_Keywords: BL Lac objects; Redshifts; Spectra, optical; Equivalent widths
Keywords: BL Lacertae objects: general ; galaxies: high-redshift
Abstract:
We report on 16 BL Lacertae objects that were proposed to be at z>1.
We present spectroscopic observations secured at the 10.4m GTC that
allowed us to assess the redshift of these sources. In particular, for
five objects, we disprove the previous value of the redshift reported
in the literature and found that they lie at z<1. Moreover, two of
them exhibit broad emission lines that are not characteristic of BL
Lacertae objects. On the other hand, for eight targets, we improve the
tentative value of z, previously based on only one feature, by
detecting a number of emission lines. Finally, in three cases, we
detect the onset of the Lyα forest at z>2.50. Based on the new
high quality spectra, we found that only half of the observed objects
can be classified as bona-fide BL Lacs.
Description:
In this paper, we present 16 objects observed with Gran Telescopio
CANARIAS (GTC) equipped with OSIRIS during 2015 Jan-Mar. The
instrument was configured with the grisms R1000B and R1000R, in order
to cover the whole spectral range of 4100-9500Å, and with a slit
width=1" yielding a spectral resolution R=800.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 88 16 The Sample of high redshift SDSS BLLac candidates
table2.dat 70 16 Log observations of high-z SDSS sources obtained
at GTC
table3.dat 52 16 Properties of the optical spectra of high z sources
table4.dat 78 55 Measurements of spectral lines
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See also:
II/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009)
V/147 : The SDSS Photometric Catalogue, Release 12 (Alam+, 2015)
VII/274 : The Roma BZCAT - 5th edition (Massaro+, 2015)
J/AJ/139/390 : Opt. selected BL Lac objects from SDSS-DR7 (Plotkin+, 2010)
J/ApJS/194/45 : QSO properties from SDSS-DR7 (Shen+, 2011)
J/ApJ/764/135 : Spectroscopic redshifts of BL Lac objects (Shaw+, 2013)
J/ApJ/780/73 : Redshifts of BL Lac objects from Fermi (Ajello+, 2014)
J/A+A/570/A126 : XShooter spectrum of 4 BL Lacs (Landoni+, 2014)
J/ApJS/217/2 : Refined associations of Fermi/LAT sources (Massaro+, 2015)
J/ApJS/218/23 : Fermi LAT third source catalog (3FGL) (Acero+, 2015)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- --- [SDSS]
6- 24 A19 --- SDSS Object Name
26- 26 A1 --- f_SDSS c = Published in Paiano+ (2017ApJ...844..120P 2017ApJ...844..120P)
28- 29 I2 h RAh [7/17] Hour of Right Ascension (J2000)
31- 32 I2 min RAm Minute of Right Ascension (J2000)
34- 38 F5.2 s RAs Second of Right Ascension (J2000)
40- 40 A1 --- DE- Sign of the Declination (J2000)
41- 42 I2 deg DEd Degree of Declination (J2000)
44- 45 I2 arcmin DEm Arcminute of Declination (J2000)
47- 50 F4.1 arcsec DEs Arcsecond of Declination (J2000)
52- 58 F7.3 deg GLON Galactic longitude, decimal degrees
60- 64 F5.2 deg GLAT Galactic latitude, decimal degrees
66- 70 F5.2 mag Vmag [17.3/19.9] Magnitude from catalog
72- 76 F5.3 mag E(B-V) [0.01/0.2] Reddening (from NED)
78- 79 A2 --- l_z [≤>] Redshift limit flag
81- 85 F5.3 --- z [0.9/3.4] Redshift (1)
87- 88 A2 --- n_z Redshift type (T=Tentative; LL=Lower limit
from intervening systems)
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Note (1): Redshift from Plotkin+ (2010, J/AJ/139/390).
For SDSS J145059.98+520111.7 redshift is given by Liao+ (2015RAA....15..313L 2015RAA....15..313L).
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- --- [SDSS]
6- 24 A19 --- SDSS Object Name
26- 29 I4 s ExpB [300/7200] Exposure time for R1000B grism
31- 40 A10 "D/M/Y" DateB Date of observation of R1000B grism
42- 44 F3.1 arcsec SeeB [0.9/2.8] Seeing during acquisition of
R1000B grism
46- 49 I4 s ExpR [700/7200] Exposure time for R1000R grism
51- 60 A10 "D/M/Y" DateR Date of observation of R1000R grism
62- 64 F3.1 arcsec SeeR [0.8/2.4] Seeing during acquisition of
R1000R grism
66- 70 F5.2 mag rmag [17/19.8] Magnitude measured from
acquisition image in r band
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- --- [SDSS]
6- 24 A19 --- SDSS Object Name
26- 28 I3 --- SNR [20/100] Average GTC S/N of the spectrum
30- 33 F4.2 0.1nm b_EWmin [0.2/1] Lower range of the minimum
equivalent width (1)
35- 38 F4.2 0.1nm B_EWmin [0.8/1.5] Upper range of the minimum
equivalent width (1)
40- 41 A2 --- l_zspec [≤>] Redshift limit flag
43- 47 F5.3 --- zspec [0.3/3.4] Proposed redshift from this work
49- 50 A2 --- f_zspec Flags on proposed redshift (2)
52- 52 A1 --- Class Class of the object (B=BLL or Q=FSRQ)
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Note (1): Range of the minimum equivalent width (EWmin) derived from different
regions of the spectrum; see Paiano et al. (2017ApJ...844..120P 2017ApJ...844..120P).
Note (2): Flags on proposed redshift as follows:
g = host galaxy absorption;
i = intervening absorption;
ll = lower limit of the redshift by assuming a BL Lac host galaxy
with MR=-22.9.
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- --- [SDSS]
6- 24 A19 --- SDSS Object Name
26- 26 A1 --- l_lambda [∼ ] Uncertainty flag on lambda
28- 34 F7.2 0.1nm lambda [4235.4/9298] Barycenter of the detected line,
in Angstrom units
36- 36 A1 --- f_lambda [* ] Barycenter contamination flag
38- 42 F5.2 0.1nm EW [0.2/87] Measured equivalent width, Angstroms
44- 60 A17 --- Line Line identification
62- 62 A1 --- l_zspec [∼ ] Uncertainty flag on zspec
64- 68 F5.3 --- zspec [0.5/3.4]? Spectroscopic redshift
70- 70 A1 --- f_zspec Flag on zspec (1)
72- 76 F5.2 [Lsun] Lum [41/43.7]? Line (log) luminosity; only for
emission features; in solar units
78- 78 A1 --- Type Feature Type (2)
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Note (1): Redshift/line center flags as follows:
* = indicates that value is determined from barycenter of detected lines
is contaminated by telluric absorptions;
? = indicates no redshift determined due to uncertain line identification.
Note (2): Feature type as follows:
G = absorption from host galaxy;
E = emission line;
A = denotes absorption lines.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 15-Jul-2019