J/ApJ/768/74 PHIBSS: CO observations of star-forming galaxies (Tacconi+, 2013)
PHIBSS: molecular gas content and scaling relations in z∼1-3 massive,
main-sequence star-forming galaxies.
Tacconi L.J., Neri R., Genzel R., Combes F., Bolatto A., Cooper M.C.,
Wuyts S., Bournaud F., Burkert A., Comerford J., Cox P., Davis M.,
Forster Schreiber N.M., Garcia-Burillo S., Gracia-Carpio J., Lutz D.,
Naab T., Newman S., Omont A., Saintonge A., Shapiro Griffin K., Shapley A.,
Sternberg A., Weiner B.
<Astrophys. J., 768, 74 (2013)>
=2013ApJ...768...74T 2013ApJ...768...74T
ADC_Keywords: Galaxies, optical ; Interferometry ; Radio lines ; Redshifts
Keywords: galaxies: evolution; galaxies: high-redshift; galaxies: ISM;
ISM: molecules
Abstract:
We present PHIBSS, the IRAM Plateau de Bure high-z blue sequence
CO(3-2) survey of the molecular gas properties in massive,
main-sequence star-forming galaxies (SFGs) near the cosmic star
formation peak. PHIBSS provides 52 CO detections in two redshift
slices at z∼1.2 and 2.2, with log(M*(M☉))≥10.4 and
log(SFR(M☉/yr))≥1.5. Including a correction for the incomplete
coverage of the M*-SFR plane, and adopting a "Galactic" value for
the CO-H2 conversion factor, we infer average gas fractions of ∼0.33
at z∼1.2 and ∼0.47 at z∼2.2. Gas fractions drop with stellar mass, in
agreement with cosmological simulations including strong star
formation feedback. Most of the z∼1-3 SFGs are rotationally supported
turbulent disks. The sizes of CO and UV/optical emission are
comparable. The molecular-gas-star-formation relation for the z=1-3
SFGs is near-linear, with a ∼0.7Gyr gas depletion timescale; changes
in depletion time are only a secondary effect. Since this timescale is
much less than the Hubble time in all SFGs between z∼0 and 2, fresh
gas must be supplied with a fairly high duty cycle over several
billion years. At given z and M*, gas fractions correlate strongly
with the specific star formation rate (sSFR). The variation of sSFR
between z∼0 and 3 is mainly controlled by the fraction of baryonic
mass that resides in cold gas.
Description:
We observed the 12CO(3-2) line emission (rest frequency 345.998GHz)
in samples of star-forming galaxies (SFGs) near the star-forming
main-sequence, selected from large UV/optical/IR lookback imaging
surveys. The CO observations were carried out between 2008 June and
2012 June with the 6x15m IRAM Plateau de Bure Millimeter
Interferometer as part of two Large Programs (see table 1).
The derived galaxy properties of the observed z∼1.2 and 2.2 SFGs are
listed in Table 2. In our final PHIBSS sample in Table 2 we also
include the six CO J=2-1 detections of the z∼1.5 BzK sample of Daddi
et al. (2010ApJ...713..686D 2010ApJ...713..686D), and the six significant CO J=2-1
detections of the z∼1 Herschel-PACS selected sample of Magnelli et al.
(2012A&A...548A..22M 2012A&A...548A..22M, labeled "PEPJ..."). Finally we also include in
Table 2 the CO detections of three somewhat lower mass
(M*=5-30x109M☉), strongly lensed SFGs between z∼2.3 and 3.1
(cB58: z=2.7, Baker et al. 2004ApJ...604..125B 2004ApJ...604..125B; "cosmic eye": z=3.1,
Coppin et al. 2007ApJ...665..936C 2007ApJ...665..936C; "eyelash": z=2.3, Swinbank et al.
2010Natur.464..733S 2010Natur.464..733S; Danielson et al. 2011MNRAS.410.1687D 2011MNRAS.410.1687D).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 83 58 CO observations
table2.dat 103 73 Derived properties
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See also:
III/268 : DEEP2 Redshift Survey, Data Release 4 (Matthews+ 2013)
J/A+A/558/A60 : CO(2-1) observations of central AGN at z=1.4 (Casasola+, 2013)
J/A+A/550/A41 : CO line survey in 0.2<z<1 of galaxies (Combes+, 2013)
J/ApJ/765/9 : Predicted CO & [CII] fluxes of HUDF galaxies (da Cunha+, 2013)
J/A+A/533/A119 : GOODS-Herschel North and South catalogs (Elbaz+, 2011)
J/ApJS/193/14 : DEEP3 Galaxy Redshift Survey: GOODS-N field (Cooper+, 2011)
J/ApJ/706/1364 : SINS survey of high-redshift gal. (Forster Schreiber+, 2009)
J/ApJ/686/948 : CO in extragalactic giant molecular clouds (Bolatto+, 2008)
J/ApJ/671/333 : Aperture photometry in NGC 5194 (Kennicutt+, 2007)
J/ApJ/647/128 : Hα observations of UV-selected galaxies (Erb, 2006)
J/ApJ/631/85 : Galaxy morphologies in the Hubble UDF (Elmegreen+, 2005)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Name Galaxy name
13- 16 A4 --- Conf [ A-D] Instrument configurations
18- 21 F4.1 h Exp [2.3/31.4] Integration time
23 A1 --- f_Exp [a] a: integration time as arcsec (?)
25- 26 I2 h RAh ? Optical hour of right ascension (J2000)
28- 29 I2 min RAm ? Optical minute of right ascension (J2000)
31- 34 F4.1 s RAs ? Optical second of right ascension (J2000)
36 A1 --- DE- [+]? Optical sign of declination (J2000)
37- 38 I2 deg DEd ? Optical degree of declination (J2000)
40- 41 I2 arcmin DEm ? Optical arcminute of declination (J2000)
43- 46 F4.1 arcsec DEs ? Optical arcsecond of declination (J2000)
48- 49 I2 h RACOh ? CO peak hour of right ascension (J2000)
51- 52 I2 min RACOm ? CO peak minute of right ascension (J2000)
54- 57 F4.1 s RACOs ? CO peak second of right ascension (J2000)
59 A1 --- DECO- [+]? CO peak sign of declination (J2000)
60- 61 I2 deg DECOd ? CO peak degree of declination (J2000)
63- 64 I2 arcmin DECOm ? CO peak arcminute of declination (J2000)
66- 69 F4.1 arcsec DECOs ? CO peak arcsecond of declination (J2000)
71- 75 F5.3 --- zCO [1/2.5]? CO redshift
77- 79 F3.1 arcsec Beam1 CO beam size 1
80 A1 --- --- [x]
81- 83 F3.1 arcsec Beam2 CO beam size 2
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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- 11 A11 --- Name Star-forming galaxy name
12- 13 A2 --- m_Name [se ] Component on Galaxy name
15- 28 A14 --- Type Kinematic class of galaxy (1)
30- 35 F6.2 km/s Vrot [2/680]? Rotation velocity
(typical uncertainty 20%-30%)
37- 40 F4.1 kpc Rh.o [1/11.2] Optical (I) half light radius (2)
42- 45 F4.1 kpc Rh.co [2.1/12]? CO(3-2) half light radius
(typical uncertainty 25%)
47- 49 I3 Msun/yr SFR [17/630] Extinction corrected star
formation rate (3)
51- 55 F5.2 Jy.km/s F(CO) [-1/13.2] CO(3-2) integrated line flux (4)
57- 61 F5.3 Jy.km/s e_F(CO) [0/0.5] F(CO) uncertainty
63- 70 E8.2 K.km/s.pc2 L(CO) CO(3-2) integrated line luminosity (4)
72- 79 E8.2 Msun Mmol Molecular gas mass (5)
81- 87 E7.2 Msun M* Stellar mass (6)
89- 92 F4.2 --- fgas [0/1] Baryonic gas fraction Mmol/(Mmol+M*)
94- 97 F4.2 [Msun/pc2] logSmol [1.4/4] Density of molecular gas
Σmol=0.5Mmol/πRh2
99-103 F5.2 [Msun/yr/kpc2] logSsf [-1/1.3] Density of star formation
ΣSFR=0.5SFR/πRh2
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Note (1): the classes are assigned from the combination of the derivable CO
kinematics and the morphological information from the HST images
(see section 3.1 for details):
* the majority are Disks, classified as a "quality A" rotating disk if it
exhibits both an extended, disk-like HST morphology and a significant,
spatially resolved CO velocity gradient; "quality B" disk galaxies have
disk-like HST morphologies but no detected velocity gradients.
* Amorphous or Compact systems
* Interacting disks
* Mergers
Note (2): Half light radius taken from HST I-band fitting for AEGIS and
Hα for BX sample. Typical uncertainty ±25%.
Note (3): Extinction corrected star formation rate from 24um luminosities
extrapolated with recent Herschel PACS calibrations to total infrared
luminosities + UV continuum for z∼1.2 objects and Hα+UV for
z∼2 galaxies; Chabrier IMF; systematic uncertainty ±35%.
Note (4): CO(3-2) (or 2-1 for BzK and PEP) integrated line flux and integrated
line luminosity; minus sign stands for a 3σ upper limit.
Note (5): Molecular gas mass, corrected for helium (1.36), a "Galactic" CO-H2
conversion factor (X=2x1020cm-2/(K.km/s)), or α=4.36, and
a CO1-0/CO3-2 ratio of 2, systematic uncertainty 50%.
Note (6): Stellar mass from SED fitting, assuming a Chabrier IMF, systematic
uncertainty ±30%.
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 25-Nov-2014