J/ApJ/830/14 SIGMA: Keck spectra of z∼2 gal. in CANDELS fields (Simons+, 2016)
Kinematic downsizing at z ∼ 2.
Simons R.C., Kassin S.A., Trump J.R., Weiner B.J., Heckman T.M., Barro G.,
Koo D.C., Guo Y., Pacifici C., Koekemoer A., Stephens A.W.
<Astrophys. J., 830, 14-14 (2016)>
=2016ApJ...830...14S 2016ApJ...830...14S (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, spectra ; Spectra, infrared ; Rotational velocities ;
Redshifts ; Velocity dispersion ; Surveys
Keywords: galaxies: evolution; galaxies: formation;
galaxies: fundamental parameters; galaxies: kinematics and dynamics
Abstract:
We present results from a survey of the internal kinematics of 49
star-forming galaxies at z∼2 in the CANDELS fields with the
Keck/MOSFIRE spectrograph, Survey in the near-Infrared of Galaxies
with Multiple position Angles (SIGMA). Kinematics (rotation velocity
Vrot and gas velocity dispersion σg) are measured from
nebular emission lines which trace the hot ionized gas surrounding
star-forming regions. We find that by z∼2, massive star-forming
galaxies (logM*/M☉≳10.2) have assembled primitive disks:
their kinematics are dominated by rotation, they are consistent with a
marginally stable disk model, and they form a Tully-Fisher relation.
These massive galaxies have values of Vrot/σg that are
factors of 2-5 lower than local well-ordered galaxies at similar
masses. Such results are consistent with findings by other studies. We
find that low-mass galaxies (logM*/M☉≲10.2) at this epoch are
still in the early stages of disk assembly: their kinematics are often
dominated by gas velocity dispersion and they fall from the
Tully-Fisher relation to significantly low values of Vrot. This
"kinematic downsizing" implies that the process(es) responsible for
disrupting disks at z∼2 have a stronger effect and/or are more active
in low-mass systems. In conclusion, we find that the period of rapid
stellar mass growth at z∼2 is coincident with the nascent assembly of
low-mass disks and the assembly and settling of high-mass disks.
Description:
The Survey in the near-Infrared of Galaxies with Multiple position
Angles (SIGMA) sample is drawn from three of the fields (GOODS-S,
GOODS-N and UDS) of the HST/WFC3 CANDELS survey (Grogin+
2011ApJS..197...35G 2011ApJS..197...35G; Koekemoer+ 2011ApJS..197...36K 2011ApJS..197...36K). All of the
spectra in GOODS-N were taken as a part of the TKRS-2 survey (Wirth+
2015, J/AJ/150/153) and a subset of the spectra in GOODS-S and UDS
have been presented in previous papers (Trump+ 2013ApJ...763L...6T 2013ApJ...763L...6T;
Barro+ 2014ApJ...795..145B 2014ApJ...795..145B).
The properties of the full sample are presented in Table 1.
The spectra in this sample were taken in the MOSFIRE H-band
(1.46-1.81um) and K-band (1.93-2.45um) on Keck I (R∼3630 in both
bands).
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 57 49 SIGMA - Observational and physical properties
table2.dat 56 49 SIGMA - Observational and kinematic properties
--------------------------------------------------------------------------------
See also:
J/AJ/150/153 : Team Keck Redshift Survey 2 (TKRS2) (Wirth+, 2015)
J/A+A/582/A21 : Merging galaxies (mis)alignments (Barrera-Ballesteros+, 2015)
J/AJ/149/178 : Redshift cat. of galaxies in GOODS-South field (Morris+, 2015)
J/ApJS/207/24 : GOODS-S CANDELS multiwavelength catalog (Guo+, 2013)
J/ApJS/206/10 : CANDELS multiwavelength catalog (Galametz+, 2013)
J/ApJ/768/74 : PHIBSS: CO obs. of star-forming galaxies (Tacconi+, 2013)
J/ApJS/203/24 : Structural param. of galaxies in CANDELS (van der Wel+, 2012)
J/A+A/539/A91 : MASSIV I. Sample properties (Contini+, 2012)
J/MNRAS/417/2347 : Tully-Fisher relation for SDSS galaxies (Reyes+, 2011)
J/ApJ/741/115 : Deep spectroscopy in the GOODS fields (Miller+, 2011)
J/A+A/533/A119 : GOODS-Herschel North and South catalogs (Elbaz+, 2011)
J/MNRAS/401/2113 : GHASP: Hα data cubes for 153 galaxies (Epinat+, 2010)
J/ApJ/706/1364 : SINS survey of high-redshift gal. (Forster Schreiber+, 2009)
J/ApJ/653/1027 : TKRS/GOODS-N Field galaxies (Weiner+, 2006)
J/A+A/455/107 : 3D spectroscopy with VLT/GIRAFFE (Flores+, 2006)
J/ApJ/633/844 : Stellar mass in disk-dominated galaxies (Pizagno+, 2005)
J/A+A/430/115 : SFR of distant galaxies (Hammer+, 2005)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 I5 --- ID [1826/26736] SIGMA galaxy ID
7- 8 I2 h RAh Hour of Right Ascension (J2000) (1)
10- 11 I2 min RAm Minute of Right Ascension (J2000) (1)
13- 17 F5.2 s RAs Second of Right Ascension (J2000) (1)
19- 19 A1 --- DE- Sign of the Declination (J2000)(1)
20- 21 I2 deg DEd Degree of Declination (J2000) (1)
23- 24 I2 arcmin DEm Arcminute of Declination (J2000) (1)
26- 30 F5.2 arcsec DEs Arcsecond of Declination (J2000) (1)
32- 35 F4.2 --- zsp [1.3/2.5] Spectroscopic redshift
37- 41 F5.2 mag Hmag [21.1/26.6] AB H band magnitude (2)
43- 47 F5.2 [Msun] Mstar [9.2/11.8] Stellar galaxy mass (3)
49- 52 F4.2 [Msun/yr] SFR [0.2/3.7] Star formation rate (3)
54- 57 F4.2 --- b/a Aspect ratio in the H band continuum (2)
--------------------------------------------------------------------------------
Note (1): The galaxy ID, RA (J2000) and DEC (J2000) are matched with the
publicly available CANDELS catalogs in
Galametz+ (2013, J/ApJS/206/10); Guo+ (2013, J/ApJS/207/24)
Note (2): Adopted from the GALFIT measurements on the HST/WFC3 F160W CANDELS
image in van der Wel+ (2012, J/ApJS/203/24).
Note (3): Derived from the full galaxy SED, as described in Section 3.2.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 I5 --- ID [1826/26736] SIGMA galaxy ID
7- 7 I1 --- Ns Number of spectra in the full SIGMA sample
9- 13 F5.1 deg PAphot [-87/89] H-band continuum photometric
major axis
15- 18 F4.1 deg e_PAphot [0.2/22] Uncertainty in PAphot
20- 25 F6.1 deg PAslit [-297/121] Keck/MOSFIRE slit position angle,
maximum vsini
27- 30 F4.1 deg DeltaPA [1.6/87.7] Difference between PAphot, PAslit
32- 34 F3.1 arcsec rv [0.1/0.4] Fixed turnover radius of the
rotation curve model
36- 38 I3 km/s vsini [5/318] Projected rotational velocity, from
the flat part of the best-fit rotation curve
40- 41 I2 km/s e_vsini [14/78] Uncertainty in vsini
43- 45 I3 km/s Vrot [5/448]? Inclination corrected rotational
velocity
47- 49 I3 km/s e_Vrot [15/150]? Uncertainty in Vrot
51- 53 I3 km/s sigg [10/129] σg, best-fit gas velocity
dispersion
55- 56 I2 km/s e_sigg [5/83] Uncertainty in σg
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 16-Jan-2017