Hα Spectroscopy of Galaxies at z > 2: Kinematics and Star Formation

By D. Erb, A. Shapley, C. Steidel, M. Pettini, K. Adelberger, M. Hunt, A. Moorwood, J. Cuby. 2003

155 citations recorded by the source corpus.

We present near-infrared spectroscopy of Hα emission lines in a sample of 16 star-forming galaxies at redshifts 2.0 < z < 2.6. Our targets are drawn from a large sample of galaxies photometrically selected and spectroscopically confirmed to lie in this redshift range. We have obtained this large sample with an extension of the broadband UnGℛ color criteria used to identify Lyman break galaxies at z ~ 3. The primary selection criterion for IR spectroscopic observation was proximity to a QSO sight line; we therefore expect the galaxies presented here to be representative of the sample as a whole. Six of the galaxies exhibit spatially extended, tilted Hα emission lines; rotation curves for these objects reach mean velocities of ~150 km s-1 at radii of ~6 kpc, without corrections for inclination or any other observational effect. The velocities and radii give a mean dynamical mass of ≥ 4 × 1010 M☉. We have obtained archival Hubble Space Telescope images for two of these galaxies; they are morphologically irregular. One-dimensional velocity dispersions for the 16 galaxies range from ~50 to ~260 km s-1, and in cases in which we have both virial masses implied by the velocity dispersions and dynamical masses derived from the spatially extended emission lines, they are in rough agreement. We compare our kinematic results with similar measurements made at z ~ 3 and find that both the observed rotational velocities and velocity dispersions tend to be larger at z ~ 2 than at z ~ 3. We also calculate star formation rates (SFRs) from the Hα luminosities and compare them with SFRs calculated from the UV continuum luminosity. We find a mean SFRHα of 16 M☉ yr-1 and an average SFRHα/SFRUV ratio of 2.4, without correcting for extinction. We see moderate evidence for an inverse correlation between the UV continuum luminosity and the ratio SFRHα/SFRUV, such as might be observed if the UV-faint galaxies suffered greater extinction. We discuss the effects of dust and star formation history on the SFRs and conclude that extinction is the most likely explanation for the discrepancy between the two SFRs.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/d65d5fce9bdd3c223c3704c697868768b2e9ac60

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

1. P. Hopkins
2. L. Hernquist
3. P. V. van Dokkum
4. M. Franx
5. R. Dav'e
6. C. Conroy
7. A. Dekel
8. D. M. Alexander

In Instrumentation

1. P. V. van Dokkum
2. M. Franx
3. P. Hopkins
4. C. Conroy
5. L. Hernquist
6. A. Shapley
7. I. Labbé
8. A. Dekel

Citations in the corpus

• The X-Ray Spectral Properties of SCUBA Galaxies (2005, background): “…galaxies (e.g., Frayer et al. 1998, 1999; Genzel et al. 2003; Neri et al. 2003; Blain et al. 2004b; Swinbank et al. 2004; Greve et al. 2005); these SMGs are 5 times more massive than the coeval optically selected field galaxies (e.g., Erb et al. 2003; Steidel et al. 2004; Swinbank et al. 2004).”
• Structure and Star Formation in Galaxies out to z = 3: Evidence for Surface Density Dependent Evolution and Upsizing (2008, background): “For example, studies have now begun of the Hα emission line kinematics and spatial distribution (e.g., Erb et al. 2003, 2006, Genzel et al. 2006, Förster Schreiber et al. 2006, Kriek et al. 2006, Law et al. 2007, Wright et al. 2007).”
• Kinemetry of SINS High-Redshift Star-Forming Galaxies: Distinguishing Rotating Disks from Major Mergers (2008, background): “Furthermore, the resolving power of 8Y10 m class telescopes and of millimeter interferometric arrays reveals velocity gradients within many of these systems (Erb et al. 2003; Genzel et al. 2003).”
• THE COSMOS-WIRCam NEAR-INFRARED IMAGING SURVEY. I. BzK-SELECTED PASSIVE AND STAR-FORMING GALAXY CANDIDATES AT z ≳ 1.4 (2009, methodology): “Similar techniques can be used at 1< z < 3 (Adelberger et al. 2004; Erb et al. 2003) and large samples of UV-selected star-forming galaxies now exist at these redshifts.”
• REST-FRAME OPTICAL SPECTRA OF THREE STRONGLY LENSED GALAXIES AT z ∼ 2 (2009, methodology): “These spectra were then flux-calibrated using A-type star observations according to the method described in Shapley et al. (2005) and Erb et al. (2003).”
• Toward an Understanding of the Rapid Decline of the Cosmic Star Formation Rate (2005, unknown): “23 emission (Hogg et al. 1998; Yan et al. 1999; Glazebrook et al. 1999; Tresse et al. 2002; Hippelein et al. 2003; Erb et al. 2003).”
• The Rest-Frame Optical Spectra of SCUBA Galaxies (2004, background): “…metallicities (which are accessible through the [N ii]/H [N2] index; Pettini & Pagel 2004), and masses, as well as more general issues such as their relation to other classes of highredshift sources such as Lyman break galaxies (LBGs; Pettini et al. 2001; Erb et al. 2003; Shapley et al. 2004).”
• Ultraviolet to Mid-Infrared Observations of Star-forming Galaxies at z ~ 2: Stellar Masses and Stellar Populations (2005, background): “…(Steidel et al. 2004; Daddi et al. 2004b) and especially in the observed nearIR, where nebular lines valuable for measurement of kinematics, star-formation rates, and chemical abundances are observationally accessible (e.g., Erb et al. 2003, 2004, 2005; Shapley et al. 2004; van Dokkum et al. 2004).”
• A Survey of Star-forming Galaxies in the 1.4 ≲ z ≲ 2.5 Redshift Desert: Overview (2004, methodology): “The data are reduced and calibrated with the procedures described by Erb et al. (2003).”
• THE STRUCTURE AND KINEMATICS OF THE CIRCUMGALACTIC MEDIUM FROM FAR-ULTRAVIOLET SPECTRA OF z ≃ 2–3 GALAXIES (2010, methodology): “Differential refraction in the near-IR is negligible for our purposes, but the observations were obtained using a 0′′.76 slit after applying a blind offset from a nearby star to the position of the galaxy measured from either an optical or near-IR continuum image (see Erb et al. 2003, 2006c).”
• SINFONI Integral Field Spectroscopy of z ~ 2 UV-selected Galaxies: Rotation Curves and Dynamical Evolution (2006, methodology): “This is in good agreement with the results of Erb et al. (2003, 2004, 2006b) and Shapley et al. (2004) from long-slit spectroscopy of various BM/BX samples.”
• THE SINS/zC-SINF SURVEY of z ∼ 2 GALAXY KINEMATICS: OUTFLOW PROPERTIES (2012, background): “(1) Erb et al. (2006), (2) Steidel et al. (2004), (3) Erb et al. (2003), (4) Kurk et al. (2009), (5) Lilly et al. (2007), (6) Lilly et al. (2009), (7) McCracken et al. (2010). tation) in the narrow velocity component, and thus maximizes the contrast between the broad and narrow components.”
• Star Formation in NGC 5194 (M51a): The Panchromatic View from GALEX to Spitzer (2005, background): “Presence of even small amounts of dust extinction in the early galaxies hampers significantly SFR measurements from the rest-frame UV emission of the high– redshift galaxies (e.g., the Lyman-break galaxies, Steidel et al (1999); Erb et al. (2003); Giavalisco et al. (2004); Reddy & Steidel (2004)).”
• Evidence for strong dynamical evolution in disc galaxies through the last 11 Gyr. GHASP VIII – a local reference sample of rotating disc galaxies for high‐redshift studies (2009, background): “…slit or integral field unit (IFU) spectroscopy of Hα emission under seeing limited conditions have suggested that at least a subset of high redshift galaxies have a disk-like morphology and show large organized rotation, which may indicate the formation of an early galactic disk (Erb et al. 2003).”
• A New Photometric Technique for the Joint Selection of Star-forming and Passive Galaxies at 1.4 ≲ z ≲ 2.5 (2004, methodology): “Recently, the same technique has been extended to work at lower redshifts 1.4< z < 2.5 (Erb et al. 2003; Adelberger et al. 2004) and large samples of UV-selected objects have been spectroscopically confirmed atz ∼ 2 (Steidel et al. 2004).”
• The Mass-Metallicity Relation at z≳2 (2006, methodology): “The data were reduced using standard procedures described by Erb et al. (2003, 2006a), and flux-calibrated with reference to near-IR standard stars.”
• The Rest-Frame Optical Properties of SCUBA Galaxies (2004, background): “It is strengthened by the apparent differences in the dynamical mass estimates of small samples from the two populations (Swinbank et al. 2004; Erb et al. 2003) and from the strong clustering seen in the far-infrared–selected population (Blain et al. 2004b).”
• THE GROWTH OF MASSIVE GALAXIES SINCE z = 2 (2009, background): “It has been possible for some time to measure gas kinematics of star forming galaxies at high redshift (e.g., Pettini et al. 1998; Erb et al. 2003; Förster Schreiber et al. 2006).”