J/AJ/155/131 z∼5 quasar luminosity function from the CFHTLS (McGreer+, 2018)
The faint end of the z=5 quasar luminosity function from the CFHTLS.
McGreer I.D., Fan X., Jiang L., Cai Z.
<Astron. J., 155, 131-131 (2018)>
=2018AJ....155..131M 2018AJ....155..131M (SIMBAD/NED BibCode)
ADC_Keywords: QSOs ; Redshifts ; Photometry, SDSS
Keywords: galaxies: high-redshift - quasars: emission lines - quasars: general
Abstract:
We present results from a spectroscopic survey of z∼5 quasars in the
CFHT Legacy Survey (Cat. II/317). Using both optical color selection and
a likelihood method, we select 97 candidates over an area of 105 deg2
to a limit of iAB<23.2, and 7 candidates in the range 23.2<iAB<23.7
over an area of 18.5 deg2. Spectroscopic observations for 43 candidates
were obtained with Gemini, MMT, and Large Binocular Telescope, of which
37 are z>4 quasars. This sample extends measurements of the quasar
luminosity function ∼1.5 mag fainter than our previous work in Sloan
Digital Sky Survey Stripe 82. The resulting luminosity function is in
good agreement with our previous results, and suggests that the faint end
slope is not steep. We perform a detailed examination of our survey
completeness, particularly the impact of the Lyα emission assumed
in our quasar spectral models, and find hints that the observed Lyα
emission from faint z∼5 quasars is weaker than for z∼3 quasars at a
similar luminosity. Our results strongly disfavor a significant
contribution of faint quasars to the hydrogen-ionizing background at z=5.
Description:
The CFHTLS Wide (Cat. II/317) encompasses a total of 150 deg2 split
over four widely spaced fields. Stacked images and derived catalogs from
the MegaPipe processing are publicly available on the CADC website
(http://www4.cadc-ccda.hia-iha.nrc-cnrc.gc.ca/en/megapipe/cfhtls/index.html)
and are described in Gwyn (2012AJ....143...38G 2012AJ....143...38G).
We obtained spectroscopic observations of faint quasar candidates from
CFHTLS-W1 using GMOS on Gemini North through classical mode observations
conducted on 2013 October 24-25 (program GN-2013B-C-1). Conditions
were excellent with 04"-0.6" seeing throughout. Spectra were obtained
through a 1" longslit and dispersed with the R400 grating, yielding a
resolution of R∼1000. The grating was centered at 7400 Å and the
OG515 blocking filter was used; this setup provides coverage from 5320
to 9500 Å.
We observed a large number of candidates with the 6.5 m MMT using the
Red Channel spectrograph during a number of observing runs from 2012
to 2014. We observed quasar candidates with the low dispersion
270 mm-1 grating, typically centered at 7500 Å with coverage from
5500 to 9700 Å. We alternated between the 1" or 1.5" slit based
on the seeing, providing resolutions of R∼640 and R∼430, respectively.
We obtained spectroscopy with the Large Binocular Telescope (LBT)
Multi-Object Double Spectrograph (MODS1) instrument on 2012 September 21.
MODS provides moderate resolution optical spectroscopy (Pogge et al.
2006SPIE.6269E..0IP). We used a 1" slit in good seeing conditions (∼0.8")
with the G670L grating (R∼1400), integrating for ∼30 minutes on each
target.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 97 97 *Complete sample of quasar candidates with
iAB<23.2
table4.dat 97 7 *Complete sample of quasar candidates with
23.2<iAB<23.7
table5.dat 33 26 Quasars with spectroscopy not included in final
candidate sample
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Note on table3.dat: Selected from the CFHTLS wide fields W1, W2, and W3, and
with partial spectroscopic coverage from Gemini-N, MMT, and LBT.
Note on table4.dat: Selected from the CFHTLS wide field W1 and with partial
spectroscopic coverage from Gemini-N.
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See also:
II/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009)
II/317 : The CFHTLS Survey (T0007 release) (Hudelot+ 2012)
J/AJ/121/2308 : Sloan Digital Sky Survey quasar photometry (Richards+, 2001)
J/AJ/131/2766 : Quasar luminosity function from SDSS-DR3 (Richards+, 2006)
J/ApJ/710/1498 : QSO luminosity function at z∼4 (Glikman+, 2010)
J/A+A/548/A66 : SDSS Quasar Catalog, DR9Q (Paris+, 2012)
J/ApJ/755/169 : 3<z<5 quasar luminosity function in the COSMOS
(Masters+, 2012)
J/ApJ/768/105 : z∼5 QSO luminosity function from SDSS Stripe 82
(McGreer+, 2013)
J/ApJ/773/14 : BOSS: quasar luminosity function (Ross+, 2013)
J/ApJ/819/24 : z>4.5 QSOs with SDSS and WISE. I. Opt. spectra (Wang+, 2016)
J/ApJ/829/33 : Luminous of high-z QSOs with SDSS and WISE. II (Yang+, 2016)
Byte-by-byte Description of file: table3.dat table4.dat
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Bytes Format Units Label Explanations
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1- 2 I2 h RAh Hour of Right Ascension (J2000)
4- 5 I2 min RAm Minute of Right Ascension (J2000)
7- 11 F5.2 s RAs Second of Right Ascension (J2000)
13 A1 --- DE- Sign of the Declination (J2000)
14- 15 I2 deg DEd Degree of Declination (J2000)
17- 18 I2 arcmin DEm Arcminute of Declination (J2000)
20- 23 F4.1 arcsec DEs Arcsecond of Declination (J2000)
25 A1 --- l_gmag [>] Limit flag on gmag (1)
26- 30 F5.2 mag gmag [23.87/29.58] g band AB magnitude (2)
32- 35 F4.2 mag e_gmag [0.02/1]? Uncertainty in gmag (2)
37- 41 F5.2 mag rmag [21.22/26.18] r band AB magnitude (2)
43- 46 F4.2 mag e_rmag [0.01/0.51] Uncertainty in rmag (2)
48- 52 F5.2 mag imag [19.38/23.69] i band AB magnitude (2)
54- 57 F4.2 mag e_imag [0.01/0.05] Uncertainty in imag (2)
59- 63 F5.2 mag zmag [19.15/23.37] z band AB magnitude (2)
65- 68 F4.2 mag e_zmag [0.01/0.11] Uncertainty in zmag (2)
70- 73 F4.2 --- PQso [0/1] Summed probability that this object is
in the full redshift range (4.5<z<5.8)
75- 78 F4.2 --- PQsoMidz [0/1] Probability that this object is a QSO
with 4.8<z<5.2
80- 84 F5.1 --- M1450 [-27.7/-22.7]? Absolute 1450Å magnitude (3)
86- 89 F4.2 --- z [4.2/5.42]? Redshift (3)
90 A1 --- u_z [?] Uncertainty flag on z (not in Table 4)
91 A1 --- n_z [abcde] Note on z (not in Table 4) (4)
93- 97 A5 --- Tel Telescope (MMT, Gem, LBT or Sloan) (not in
Table 4) (3)
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Note (1): Lower limits on magnitudes are the 50% completeness limits for the
associated CFHTLS pointing from Gwyn (2012AJ....143...38G 2012AJ....143...38G).
Note (2): Magnitudes are on the AB system (Oke & Gunn 1983ApJ...266..713O 1983ApJ...266..713O) and
have been corrected for Galactic extinction.
Note (3): No value for spectroscopic non-quasars.
Note (4): Note as follows:
a = Binary quasar; see McGreer et al. (2016AJ....151...61M 2016AJ....151...61M);
b = Lyα-emitting galaxy; see McGreer et al. (2018MNRAS.479..435M 2018MNRAS.479..435M);
c = See discussion in Section 4.2;
d = Stripe 82 quasar included in McGreer et al. (2013, J/ApJ/768/105);
e = Also reported in Ikeda et al. (2017ApJ...846...57I 2017ApJ...846...57I).
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 2 I2 h RAh Hour of Right Ascension (J2000)
4- 5 I2 min RAm Minute of Right Ascension (J2000)
7- 11 F5.2 s RAs Second of Right Ascension (J2000)
13 A1 --- DE- Sign of the Declination (J2000)
14- 15 I2 deg DEd Degree of Declination (J2000)
17- 18 I2 arcmin DEm Arcminute of Declination (J2000)
20- 23 F4.1 arcsec DEs Arcsecond of Declination (J2000)
25- 28 F4.2 --- z [4.18/5.31]? Redshift (1)
30- 33 A4 --- Source Imaging source from which the object was
selected (2)
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Note (1): Three non-quasars from the Stripe 82 complete sample given in
McGreer et al. (2013, J/ApJ/768/105) are listed with dashes for the redshift
entry.
Note (2): Imaging source as follows:
DR7 = SDSS DR7 (Cat. II/294);
S82 = SDSS Stripe 82;
CFHT = CFHTLS Wide (Cat. II/317).
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History:
From electronic version of the journal
References:
McGreer et al. Paper I. 2013ApJ...768..105M 2013ApJ...768..105M, Cat. J/ApJ/768/105
(End) Tiphaine Pouvreau [CDS] 08-Nov-2018