J/ApJ/859/53 Lyα candidates from a MUSE survey of 6 AGNs (Marino+, 2018)
Dark galaxy candidates at redshift ∼3.5 detected with MUSE.
Marino R. A., Cantalupo S., Lilly S.J., Gallego S.G., Straka L.A.,
Borisova E., Pezzulli G., Bacon R., Brinchmann J., Carollo C.M., Caruana J.,
Conseil S., Contini T., Diener C., Finley H., Inami H., Leclercq F.,
Muzahid S., Richard J., Schaye J., Wendt M., Wisotzki L.
<Astrophys. J., 859, 53 (2018)>
=2018ApJ...859...53M 2018ApJ...859...53M
ADC_Keywords: Active gal. nuclei; QSOs; Redshifts; Spectra, optical
Equivalent widths; Intergalactic medium; Surveys
Keywords: galaxies: formation; galaxies: high-redshift;
galaxies: star formation; intergalactic medium;
quasars: emission lines; quasars: general
Abstract:
Recent theoretical models suggest that the early phase of galaxy
formation could involve an epoch when galaxies are gas rich but
inefficient at forming stars: a "dark galaxy" phase. Here, we report
the results of our Multi-Unit Spectroscopic Explorer (MUSE) survey for
dark galaxies fluorescently illuminated by quasars at z>3. Compared to
previous studies which are based on deep narrowband (NB) imaging, our
integral field survey provides a nearly uniform sensitivity coverage
over a large volume in redshift space around the quasars as well as
full spectral information at each location. Thanks to these unique
features, we are able to build control samples at large redshift
distances from the quasars using the same data taken under the same
conditions. By comparing the rest-frame equivalent width (EW0)
distributions of the Lyα sources detected in proximity to the
quasars and in control samples, we detect a clear correlation between
the locations of high-EW0 objects and the quasars. This correlation is
not seen in other properties, such as Lyα luminosities or volume
overdensities, suggesting the possible fluorescent nature of at least
some of these objects. Among these, we find six sources without
continuum counterparts and EW0 limits larger than 240Å that are the
best candidates for dark galaxies in our survey at z>3.5. The volume
densities and properties, including inferred gas masses and star
formation efficiencies, of these dark galaxy candidates are similar to
those of previously detected candidates at z∼2.4 in NB surveys.
Moreover, if the most distant of these are fluorescently illuminated
by the quasar, our results also provide a lower limit of t=60Myr on
the quasar lifetime.
Description:
Our observations were carried out with the Multi-Unit Spectroscopic
Explorer (MUSE), the second-generation IFU mounted on the Very Large
Telescope (VLT) at the Nasmyth B focus of the Yepun (Unit Telescope 4)
in Paranal, Chile. MUSE has a uniquely powerful performance: a
relatively large FoV (in wide-field mode, WFM, 1'x1') combined with
the excellent spatial sampling (0.2") and spectral resolutions (R from
∼1750 to ∼3500) over a wide optical wavelength window (from 4650 to
9300Å) and high throughput (35% at 7500Å).
The six medium-deep fields at z>3 analyzed in this study were observed
between 2014 September and 2016 April. They form part of two MUSE
Guaranteed Time Observation (GTO) programs (094.A-0396, 095.A-0708,
096.A-0345, 097.A-0251, 098.A-0678 PI: S. Lilly; 094.A-0131,
095.A-0200, 096.A-0222, 097.A-0089, 098.A-0216; PI: J. Schaye).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 82 6 Major properties of the MUSE medium-deep fields
table5.dat 63 175 Physical properties of the Lyα candidates
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See also:
VI/109 : Pop. Synthesis Models at very low metallicities (Schaerer, 2003)
VII/260 : The SDSS-DR7 quasar catalog (Schneider+, 2010)
VII/258 : Quasars and Active Galactic Nuclei (13th Ed.) (Veron+ 2010)
J/A+A/392/395 : Ks-band magnitudes of the K20 sample (Cimatti+, 2002)
J/ApJ/596/768 : Optical depths in 19 QSOs (Schaye+, 2003)
J/A+A/523/A64 : UV properties of starbursts (Raiter+, 2010)
J/A+A/548/A66 : SDSS Quasar Catalog, DR9Q (Paris+, 2012)
J/ApJ/763/37 : Metals in SDSS QSOs. I. 1.5<z<4.5 CIV abs. (Cooksey+, 2013)
J/ApJ/776/136 : QPQ VI. HI absorption of z∼2 quasars (Prochaska+, 2013)
J/ApJ/762/L19 : Quasar pairs spectroscopy (Prochaska+, 2013)
J/A+A/556/A141 : ESO-UVES Advanced Data Products (EUADP) sample (Zafar+, 2013)
J/A+A/575/A75 : MUSE 3D view of HDF-S (Bacon+, 2015)
J/MNRAS/452/2553 : Sample of foreground-background QSO pairs (Johnson+, 2015)
J/MNRAS/449/4204 : WFC3/UVIS quasar-stacked spectrum at z≃2.4 (Lusso+, 2015)
J/AJ/150/111 : KODIAQ DR1 (O'Meara+, 2015)
J/ApJ/831/7 : SDSS-RM project: peak velocities of QSOs (Shen+, 2016)
J/A+A/608/A8 : MUSE Hubble Ultra Deep Field Survey. VIII (Leclercq+, 2017)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Field AGN name
12- 13 I2 h RAh Hour of right ascension (J2000)
15- 16 I2 min RAm Minute of right ascension (J2000)
18- 21 F4.1 s RAs Second of right ascension (J2000)
23 A1 --- DE- Sign of declination (J2000)
24- 25 I2 deg DEd Degree of declination (J2000)
27- 28 I2 arcmin DEm Arcminute of declination (J2000)
30- 31 I2 arcsec DEs Arcsecond of declination (J2000)
33- 37 F5.3 --- z [3/3.8] Redshift values from the catalog of
Veron+ (2010, VII/258)
39- 43 F5.3 --- zCIV [3/3.8] Redshift from the luminosity-corrected
CIV measurement (1)
45- 49 F5.2 h Exp [8.7/20] Exposure time
51- 61 A11 --- Class Object class (2)
63- 67 F5.2 mag Vmag [17.8/24.8] V-band AB magnitude in 3" diameter
aperture (3)
69- 72 F4.2 arcsec PSF [0.7/0.9] Mean FWHM of the Gaussian fit (4)
74- 77 F4.1 mag Flim [28.2/29] 3σ flux continuum limit (AB mag)
within a 1" diameter aperture
79- 82 F4.1 mag FLyaS [30.2/31] Lyα sensitivity (AB mag)
within a 1" diameter aperture
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Note (1): Computed from the luminosity-corrected (Shen+ 2016, J/ApJ/831/7) CIV
emission-line measurement from the MUSE spectra.
Note (2): Class refers to the type of powering source in the field, i.e., AGN,
radio-quiet (RQ) QSO, and radio-loud (RL) QSO on the basis of the
radio flux measurements (Flux[1.4GHz] threshold 5mJy) presented in the
Veron-Cetty & Veron (2010, VII/258) catalog.
Note (3): V (AB mag) measured in a 3" diameter aperture on the reconstructed
MUSE-V image, i.e., MUSE datacube convolved with the V-Johnson filter,
without accounting for the foreground Galactic absorption.
Note (4): Mean FWHM of the Gaussian fit measured on different point sources in
the final combined datacube at 7000Å using both SExtractor and
QFitsView tools.
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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- 10 A10 --- Field Field identifier
12- 15 A4 --- ID Object identifier (1)
19- 21 I3 --- Area [26/432] Object area
23- 25 F3.1 --- zphot [2.9/4] Photometric redshift
27- 30 F4.2 10-20W/m2 FLya [0.02/8.7] Lyα flux;
in units of 1e-17erg/s/cm2
32- 35 F4.2 10-20W/m2 e_FLya [0.01/0.1] Uncertainty in FLya
37- 42 F6.2 10+34W LLya [0.1/130] Lyα luminosity;
in units of 1e41erg/s
44- 48 F5.2 10-22W/m2/nm FCont [-0.3/45] Continuum flux;
in units of 1e-20erg/s/cm2/Å
50- 53 F4.2 10-22W/m2/nm e_FCont [0.1/1.5] Uncertainty in FCont
55 A1 --- l_EW0Lya Limit flag on EW0Lya
57- 59 I3 0.1nm EW0Lya [3/211] Lyα equivalent width;
in Angstrom units
61- 63 I3 0.1nm e_EW0Lya [1/460]? Uncertainty in EW0Lya
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Note (1): The second to last target, Field=Q2000-330 ID=5r, might also be
classified as an [OII] emitter, although this alternative
interpretation relies on the uncertain [OIII] detection which is
hampered by telluric sky lines.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 28-May-2019