J/MNRAS/472/2085 ALHAMBRA fields type-I AGN with ELDAR (Chaves-Montero+, 2017)
ELDAR, a new method to identify AGN in multi-filter surveys:
the ALHAMBRA test-case.
Chaves-Montero J., Bonoli S., Salvato M., Greisel N., Diaz-Garcia L.A.,
Lopez-Sanjuan C., Viironen K., Fernandez-Soto A., Povic M., Ascaso B.,
Arnalte-Mur P., Masegosa J., Matute I., Marquez I., Cenarro A. J.,
Abramo L.R., Ederoclite A., Alfaro E.J.
<Mon. Not. R. Astron. Soc. 472, 2085 (2017)>
=2017MNRAS.472.2085C 2017MNRAS.472.2085C (SIMBAD/NED BibCode)
ADC_Keywords: QSOs ; Spectrophotometry ; Redshifts ; Surveys
Keywords: methods: data analysis - techniques: photometric - surveys -
galaxies: active - galaxies: distances and redshifts -
quasars: emission lines
Abstract:
We present ELDAR, a new method that exploits the potential of medium-
and narrow-band filter surveys to securely identify active galactic
nuclei (AGN) and determine their redshifts. Our methodology improves
on traditional approaches by looking for AGN emission lines expected
to be identified against the continuum, thanks to the width of the
filters. To assess its performance, we apply ELDAR to the data of the
ALHAMBRA survey, which covered an effective area of 2.38deg2 with 20
contiguous medium-band optical filters down to F814W=24.5. Using two
different configurations of ELDAR in which we require the detection of
at least 2 and 3 emission lines, respectively, we extract two
catalogues of type-I AGN. The first is composed of 585 sources (79% of
them spectroscopically-unknown) down to F814W=22.5 at zphot>1, which
corresponds to a surface density of 209 deg-2. In the second, the 494
selected sources (83% of them spectroscopically-unknown) reach
F814W=23 at zphot>1.5, for a corresponding number density of
176deg-2. Then, using samples of spectroscopically-known AGN in the
ALHAMBRA fields, for the two catalogues we estimate a completeness of
73% and 67%, and a redshift precision of 1.01% and 0.86% (with
outliers fractions of 8.1% and 5.8%). At z>2, where our selection
performs best, we reach 85% and 77% completeness and we find no
contamination from galaxies.
Description:
The catalogues ALH2L and ALH3L contain type-I AGN in the ALHAMBRA
fields identified by using the 2- and 3-lines mode of ELDAR with the
publicly available multi-band data of the ALHAMBRA survey,
respectively, and they contain 585 and 494 sources. For each type-I
AGN coordinates, redshift, best-fit template, PSF ALHAMBRA magnitudes,
Stellarity, and properties of the AGN emission lines detected by ELDAR
are given.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
alh2l.dat 530 585 ALH2L catalogue
alh3l.dat 530 494 ALH3L catalogue
--------------------------------------------------------------------------------
See also:
J/AJ/139/1242 : ALHAMBRA photometric system (Villegas+, 2010)
J/MNRAS/441/2891 : ALHAMBRA Survey (Molino+, 2014)
J/MNRAS/435/3444 : ALHAMBRA survey morphological catalogue (Povic+, 2013)
J/MNRAS/452/549 : ALHAMBRA survey galaxy clusters and groups (Ascaso+, 2015)
Byte-by-byte Description of file: alh2l.dat alh3l.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- Name Identification number (ALHXLYYY) (1)
10- 17 F8.4 deg RAdeg Right ascension (J2000)
19- 26 F8.4 deg DEdeg Declination (J2000)
28- 32 F5.3 --- z Photometric redshift
34 I1 --- Mask [0,1] Mask (2)
36- 37 I2 --- Temp [1/12] Best-fit extragalactic template (3)
39- 42 F4.2 --- ExtB Best-fit colour excess
44- 49 F6.3 mag F814W F814W magnitude (4)
51- 55 F5.3 mag e_F814W F814W uncertainty (4)
57- 60 F4.2 --- Stell [0,1] Stellarity (1 = point-like sources,
0 = extended sources)
62- 68 F7.3 mag F365W ?=-99.000 F365W magnitude
70- 76 F7.3 mag e_F365W ?=-99.000 F365W uncertainty
78- 84 F7.3 mag F396W ?=-99.000 F396W magnitude
86- 92 F7.3 mag e_F396W ?=-99.000 F396W uncertainty
94-100 F7.3 mag F427W ?=-99.000 F427W magnitude
102-108 F7.3 mag e_F427W ?=-99.000 F427W uncertainty
110-116 F7.3 mag F458W ?=-99.000 F458W magnitude
118-124 F7.3 mag e_F458W ?=-99.000 F458W uncertainty
126-132 F7.3 mag F489W ?=-99.000 F489W magnitude
134-140 F7.3 mag e_F489W ?=-99.000 F489W uncertainty
142-148 F7.3 mag F520W ?=-99.000 F520W magnitude
150-156 F7.3 mag e_F520W ?=-99.000 F520W uncertainty
158-164 F7.3 mag F551W ?=-99.000 F551W magnitude
166-172 F7.3 mag e_F551W ?=-99.000 F551W uncertainty
174-180 F7.3 mag F582W ?=-99.000 F582W magnitude
182-188 F7.3 mag e_F582W ?=-99.000 F582W uncertainty
190-196 F7.3 mag F613W ?=-99.000 F613W magnitude
198-204 F7.3 mag e_F613W ?=-99.000 F613W uncertainty
206-212 F7.3 mag F644W ?=-99.000 F644W magnitude
214-220 F7.3 mag e_F644W ?=-99.000 F644W uncertainty
222-228 F7.3 mag F675W ?=-99.000 F675W magnitude
230-236 F7.3 mag e_F675W ?=-99.000 F675W uncertainty
238-244 F7.3 mag F706W ?=-99.000 F706W magnitude
246-252 F7.3 mag e_F706W ?=-99.000 F706W uncertainty
254-260 F7.3 mag F737W ?=-99.000 F737W magnitude
262-268 F7.3 mag e_F737W ?=-99.000 F737W uncertainty
270-276 F7.3 mag F768W ?=-99.000 F768W magnitude
278-284 F7.3 mag e_F768W ?=-99.000 F768W uncertainty
286-292 F7.3 mag F799W ?=-99.000 F799W magnitude
294-300 F7.3 mag e_F799W ?=-99.000 F799W uncertainty
302-308 F7.3 mag F830W ?=-99.000 F830W magnitude
310-316 F7.3 mag e_F830W ?=-99.000 F830W uncertainty
318-324 F7.3 mag F861W ?=-99.000 F861W magnitude
326-332 F7.3 mag e_F861W ?=-99.000 F861W uncertainty
334-340 F7.3 mag F892W ?=-99.000 F892W magnitude
342-348 F7.3 mag e_F892W ?=-99.000 F892W uncertainty
350-356 F7.3 mag F923W ?=-99.000 F923W magnitude
358-364 F7.3 mag e_F923W ?=-99.000 F923W uncertainty
366-372 F7.3 mag F954W ?=-99.000 F954W magnitude
374-380 F7.3 mag e_F954W ?=-99.000 F954W uncertainty
382-388 F7.3 mag FJ ?=-99.000 NIR-J magnitude
390-396 F7.3 mag e_FJ ?=-99.000 NIR-J uncertainty
398-404 F7.3 mag FH ?=-99.000 NIR-H magnitude
406-412 F7.3 mag e_FH ?=-99.000 NIR-H uncertainty
414-420 F7.3 mag FKs ?=-99.000 NIR-Ks magnitude
422-428 F7.3 mag e_FKs ?=-99.000 NIR-Ks uncertainty
430-431 I2 --- line1 Band where the OVI+Lyman beta
complex is detected (5)
433-438 F6.3 [-] log(SNRl1) log_10(SNR) in the band where the
OVI+Lyman beta complex is detected
440-445 F6.3 [-] log(Slin1) log_10(Slin) in the band where the
OVI+Lyman beta complex is detected
447-448 I2 --- line2 Band where the Lyman alpha line
is detected (5)
450-455 F6.3 [-] log(SNRl2) log_10(SNR) in the band where the
Lyman alpha line is detected
457-462 F6.3 [-] log(Slin2) log_10(Slin) in the band where the
Lyman alpha line is detected
464-465 I2 --- line3 Band where the SiIV+OIV
complex is detected (5)
467-472 F6.3 [-] log(SNRl3) log_10(SNR) in the band where the
SiIV+OIV complex is detected
474-479 F6.3 [-] log(Slin3) log_10(Slin) in the band where the
SiIV+OIV complex is detected
481-482 I2 --- line4 Band where the CIV line is
detected (5)
484-489 F6.3 [-] log(SNRl4) log_10(SNR) in the band where the
CIV line is detected
491-496 F6.3 [-] log(Slin4) log_10(Slin) in the band where the
CIV line complex is detected
498-499 I2 --- line5 Band where the CIII] line is
detected (5)
501-506 F6.3 [-] log(SNRl5) log_10(SNR) in the band where the
CIII] line is detected
508-513 F6.3 [-] log(Slin5) log_10(Slin) in the band where the
CIII] line is detected
515-516 I2 --- line6 Band where the MgII line is
detected (5)
518-523 F6.3 [-] log(SNRl6) log_10(SNR) in the band where the
MgII line is detected
525-530 F6.3 [-] log(Slin6) log_10(Slin) in the band where the
MgII line is detected (5)
--------------------------------------------------------------------------------
Note (1): The format is ALHXLYYY, where the value of X is 2 and 3 for the
ALH2L and ALH3L catalogues, respectively, and YYY is the number of the object.
The IDs are ranked according to zphot.
Note (2): ALHAMBRA angular mask of Arnalte-Mur et al. (2014MNRAS.441.1783A 2014MNRAS.441.1783A).
It describes the sky area which has been reliably observed as follows:
1 = inside the mask
0 = outside the mask
Note (3): Extragalactic templates that we introduce in LePHARE as follows:
---------------------------------------------------------------
Index Template Class References
---------------------------------------------------------------
1 = I2249170TQSO1_30 Quasar 30% + Gal. 70% [1]
2 = I2249160TQSO1_40 Quasar 40% + Gal. 60% [1]
3 = I2249150TQSO1_50 Quasar 50% + Gal. 50% [1]
4 = I2249140TQSO1_60 Quasar 60% + Gal. 40% [1]
5 = plI2249130TQSO170 Quasar 70% + Gal. 30% [1]
6 = plI2249120TQSO180 Quasar 80% + Gal. 20% [1]
7 = plQSODR2029t0 Quasar low lum. [1]
8 = pl_QSOH Quasar high lum. [1]
9 = pl_TQSO1 Quasar high IR lum. [1]
10 = qso-0.2_84 Quasar synthetic [2]
11 = QSO_VVDS Quasar [3]
12 = QSO_SDSS Quasar [4]
---------------------------------------------------------------
References.
[1] Salvato et al. (2009ApJ...690.1250S 2009ApJ...690.1250S)
[2] LePHARE distribution
[3] VVDS composite (Gavignaud et al., 2006, Cat. J/A+A/457/79)
[4] SDSS composite (Vanden Berk et al., 2001AJ....122..549V 2001AJ....122..549V)
Templates starting with pl are extended into the UV using a power law
(see Salvato et al., 2009ApJ...690.1250S 2009ApJ...690.1250S).
Note (4): The F814W ALHAMBRA band is a synthetic band that corresponds to the
HST/ACD F814W band. It was employed to create the ALHAMBRA detection
images. The signal-to-noise ratio in the detection band is 1/e_F814W.
Note (5): ALHAMBRA band where AGN emission lines fall.
It is 99 for no detections and 0 for lines outside the ALHAMBRA wavelength
range. For detected lines we include the SNR in the line that they fall and
the significance with which the line is detected, Slin.
--------------------------------------------------------------------------------
Acknowledgements:
Jonas Chaves-Montero, jonaschavesmontero22(at)gmail.com
(End) Jonas Chaves-Montero [CEFCA, Spain], Patricia Vannier [CDS] 29-Aug-2017