Resolved spectroscopy of gravitationally lensed galaxies: recovering coherent velocity fields in subluminous z ~ 2-3 galaxies

By T. Jones, M. Swinbank, Richard S. Ellis, J. Richard, D. Stark. 2009

189 citations recorded by the source corpus.

We present spatially resolved dynamics for six strongly lensed star-forming galaxies at z= 1.7–3.1 , each enlarged by a linear magnification factor of ~ ×8 . Using the Keck laser guide star AO system and the OH-Suppressing Infra-Red Imaging Spectrograph integral field unit spectrograph, we resolve kinematic and morphological detail in our sample with an unprecedented fidelity, in some cases achieving spatial resolutions of ≃100 pc. With one exception our sources have diameters ranging from 1 to 7 kpc, integrated star formation rates of 2–40 M_⊙ yr^(−1) (uncorrected for extinction) and dynamical masses of 10^(9.7−10.3) M_⊙ . With this exquisite resolution, we find that four of the six galaxies display coherent velocity fields consistent with a simple rotating disc model. Our model fits imply ratios for the systemic to random motion, V_c sin i/σ , ranging from 0.5 to 1.3 and Toomre disc parameters Q < 1 . The large fraction of well-ordered velocity fields in our sample is consistent with data analysed for larger, more luminous sources at this redshift. We demonstrate that the apparent contradiction with earlier dynamical results published for unlensed compact sources arises from the considerably improved spatial resolution and sampling uniquely provided by the combination of adaptive optics and strong gravitational lensing. Our high-resolution data further reveal that all six galaxies contain multiple giant star-forming H ii regions whose resolved diameters are in the range 300 pc to 1.0 kpc, consistent with the Jeans length expected in the case of dispersion support. From the kinematic data, we calculate that these regions have dynamical masses of 10^(8.8−9.5) M_⊙, also in agreement with local data. However, the density of star formation in these regions is ~100× higher than observed in local spirals; such high values are only seen in the most luminous local starbursts. The global dynamics and demographics of star formation in these H ii regions suggest that vigorous star formation is primarily governed by gravitational instability in primitive rotating discs. The physical insight provided by the combination of adaptive optics and gravitational lensing suggests it will be highly valuable to locate many more strongly lensed distant galaxies with high star formation rates before the era of the next-generation ground-based telescopes when such observations will become routine.

Subfields: Astronomy and Astrophysics, Global and Planetary Change

View Paper: https://www.semanticscholar.org/paper/3e1f8eccfd2b8f11fb03c0b5e4cb0c2d48ddea02

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In Astronomy and Astrophysics

1. P. Hopkins
2. L. Hernquist
3. A. Dekel
4. R. Dav'e
5. T. Naab
6. R. Somerville
7. P. V. van Dokkum
8. R. Genzel

In Global and Planetary Change

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2. T. Naab
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4. B. Oppenheimer
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6. D. Erb
7. P. V. van Dokkum
8. D. Ceverino

Citations in the corpus

• Adaptive Optics for Astronomy (2012, background): “Even higher linear resolutions, corresponding to as little as ∼ 100 pc, can be reached if AO is applied to gravitationally lensed objects (Jones et al. 2010, Stark et al. 2008).”
• SHORT-LIVED STAR-FORMING GIANT CLUMPS IN COSMOLOGICAL SIMULATIONS OF z ≈ 2 DISKS (2010, background): “…spectrally resolved line emissions reveal ordered rotation andhigh velocity dispersions, widespread across the disks at≈ 50− 80 kms−1 (Genzel et al. 2006, 2008; Förster Schreiber et al. 2006, 2009; Shapiro et al. 2008; Cresci et al. 2009; Law et al. 2009; Jones et al. 2010; Swinbank et al. 2010).”
• CONSTRAINTS ON THE ASSEMBLY AND DYNAMICS OF GALAXIES. I. DETAILED REST-FRAME OPTICAL MORPHOLOGIES ON KILOPARSEC SCALE OF z ∼ 2 STAR-FORMING GALAXIES (2010, background): “Concurring results on the kinematic mix atz∼ 1− 3 have been found by other groups (e.g., Erb et al. 2003, 2004, 2006; Wright et al. 2007, 2009; Law et al. 2007b, 2009; Stark et al. 2008; Épinat et al. 2009; Jones et al. 2010).”
• A unified model for galactic discs: star formation, turbulence driving, and mass transport (2017, methodology): “Jones et al. (2010).”
• The properties of the star-forming interstellar medium at z = 0.84-2.23 from HiZELS : mapping the internal dynamics and metallicity gradients in high-redshift disc galaxies. (2012, background): “…in the SINS survey which show the most prominent rotational support (rms of 10–80 km s−1 and χ2ν = 0.2–20; Cresci et al. 2009), as well as to the high-resolution studies of gravitationally lensed galaxies from Jones et al. (2010b) and Stark et al. (2008) (which have an average χ2ν = 3.5 ± 0.8).”
• The KMOS Redshift One Spectroscopic Survey (KROSS):dynamical properties, gas and dark matter fractions of typical z~1 star-forming galaxies (2016, background): “Other studies have focused on IFU observations of small samples of gravitationally lensed galaxies (e.g. Swinbank et al. 2006; Jones et al. 2010; Livermore et al. 2015).”
• THEORETICAL EVOLUTION OF OPTICAL STRONG LINES ACROSS COSMIC TIME (2013, methodology): “The steepest gradients were obtained by observing gravitationally lensed galaxies with integral field spectrographs with laser-guided adaptive optics (Jones et al. 2010; Yuan et al. 2011; Jones et al. 2013).”
• THE SINS SURVEY OF z ∼ 2 GALAXY KINEMATICS: PROPERTIES OF THE GIANT STAR-FORMING CLUMPS (2010, background): “…of lower mass disks (∼a (A color version of this figure is available in the online journal.) few 109 M ) from the survey of z ∼ 1–3 lensed SFGs by Jones et al. (2010), and from mostly lower mass (Mdyn ∼ (0.3–3) × 1010 M ) and compact (R1/2 ∼ 0.9–2 kpc) but wellresolved (with AO) “dispersion…”
• THE INTERSTELLAR MEDIUM IN DISTANT STAR-FORMING GALAXIES: TURBULENT PRESSURE, FRAGMENTATION, AND CLOUD SCALING RELATIONS IN A DENSE GAS DISK AT z = 2.3 (2011, background): “Evidence is accumulating that the dominant mode of star formation may be very different in early systems than that found in most local disks (e.g. Bournaud & Elmegreen 2009; Jones et al. 2010).”
• EVIDENCE FOR WIDE-SPREAD ACTIVE GALACTIC NUCLEUS-DRIVEN OUTFLOWS IN THE MOST MASSIVE z ∼ 1–2 STAR-FORMING GALAXIES (2014, background): “…growing evidence that a majority of massive z ∼ 1–2.5 SFGs are disks based on kinematic and morphological properties (see also, e.g., Shapiro et al. 2008; Genzel et al. 2008, 2014a; Förster Schreiber et al. 2009; Épinat et al. 2009, 2012; Jones et al. 2010; Wuyts et al. 2011b; Lang et al. 2014).”
• HYDRODYNAMICS OF HIGH-REDSHIFT GALAXY COLLISIONS: FROM GAS-RICH DISKS TO DISPERSION-DOMINATED MERGERS AND COMPACT SPHEROIDS (2010, background): “…of high-redshift star forming galaxies concerned only very massive galaxies (above the critical mass L∗), recent studies of z > 1 lensed galaxies find that gravitational instabilities and turbulent clumps could also be dominant in lower-mass galaxies (Jones et al. 2010; Swinbank et al. 2010).”
• Ultraviolet emission lines in young low-mass galaxies at z ≃ 2: physical properties and implications for studies at z > 7 (2014, methodology): “The mass model in Abell 68 is described in Richard et al. (2007) and Richard et al. (2010), while the MACS 0451 mass c© 2013 RAS, MNRAS000, 1–22 model is based on that presented in Jones et al. (2010), updated to include the new multiple images presented in this work.”
• Relativistic jet feedback – III. Feedback on gas discs (2018, background): “The settled density thus forms a clumpy turbulent disk with average cloud sizes of ∼ 100 pc, similar to clumpy star forming regions observed in high redshift galaxies (Jones et al. 2010; Livermore et al. 2015).”
• Ionized gas outflows and global kinematics of low-z luminous star-forming galaxies (2014, background): “…et al. 2006, 2009; Genzel et al. 2006, 2008; Cresci et al. 2009; Wright et al. 2007; Starkenburg et al 2009; Epinat et al. 2009; LemoineBusserolle & Lamareille 2010; Law et al. 2009; Jones et al. 2010), sampling a wide range of dynamical masses, sizes, and star formation densities.”