DEEP FABRY-PEROT Hα OBSERVATIONS OF NGC 7793: A VERY EXTENDED Hα DISK AND a TRULY DECLINING ROTATION CURVE

Dicaire, Isabelle; Carignan, C.; Amram, P.; Marcelin, M.; Hlavacek-Larrondo, J.; Denus–Baillargeon, M.-M. de; Daigle, Olivier; Hernandez, O.

doi:10.1088/0004-6256/135/6/2038

Cited by 35 publications

(36 citation statements)

References 57 publications

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“…We note that our stacked rotation curve also falls-off more steeply than the rare cases of observed declining rotation curves in some local spirals (e.g. Casertano & van Gorkom 1991;Dicaire et al 2008;Noordermeer et al 2008). There might be additional kinematical effects such as warping, perturbations by minor merging, or radial motions that are capable of producing the outer fall-off observed in our stack.…”

Section: Comparison To Rotation Curves Of Local Spiralsmentioning

confidence: 44%

Falling Outer Rotation Curves of Star-forming Galaxies at 0.6 ≲ z ≲ 2.6 Probed with KMOS^3D and SINS/zC-SINF

Lang

Schreiber

Genzel

et al. 2017

ApJ

115

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We exploit the deep resolved Hα kinematic data from the KMOS 3D and SINS/zC-SINF surveys to examine the largely unexplored outer disk kinematics of star-forming galaxies (SFGs) out to the peak of cosmic star formation. Our sample contains 101 SFGs representative of the more massive (9.3 log M * /M ⊙ 11.5) main sequence population at 0.6 z 2.6. Through a novel stacking approach we are able to constrain a representative rotation curve extending out to ∼ 4 effective radii. This average rotation curve exhibits a significant drop in rotation velocity beyond the turnover, with a slope of ∆V/∆R = −0.26 +0.10 −0.09 in units of normalized coordinates V/V max and R/R turn . This result confirms that the fall-off seen previously in some individual galaxies is a common feature of our sample of high-z disks. We show that this outer fall-off strikingly deviates from the flat or mildly rising rotation curves of local spiral galaxies of similar masses. We furthermore compare our data with models including baryons and dark matter demonstrating that the falling stacked rotation curve can be explained by a high mass fraction of baryons relative to the total dark matter halo (m d 0.05) in combination with a sizeable level of pressure support in the outer disk. These findings are in agreement with recent studies demonstrating that star-forming disks at high redshift are strongly baryon dominated within the disk scale, and furthermore suggest that pressure gradients caused by large turbulent gas motions are present even in their outer disks. We demonstrate that these results are largely independent of our model assumptions such as the presence of a central stellar bulge, the effect of adiabatic contraction at fixed m d , and variations in the concentration parameter.

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Section: Comparison To Rotation Curves Of Local Spiralsmentioning

confidence: 44%

Falling Outer Rotation Curves of Star-forming Galaxies at 0.6 ≲ z ≲ 2.6 Probed with KMOS^3D and SINS/zC-SINF

Lang

Schreiber

Genzel

et al. 2017

ApJ

115

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“…We take (i) the rotation curve published by Carignan & Puche (1990), (ii) that by de Blok et al (2008) and (iii) three rotation curves published by Dicaire et al (2008). The latter three curves were merged so as to obtain a single rotation curve.…”

Section: Resultsmentioning

confidence: 99%

Global disc models for galaxies NGC 1365, 6946, 7793 and UGC 6446

Jałocha

Bratek

Kutschera

et al. 2010

Monthly Notices of the Royal Astronomical Society

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Spiral galaxies are studied using a simple global disc model as a means for approximate determination of mass profiles. Based on rotation curves and the amount of gas (H i+He), we find global surface mass densities consistent with measurements and compare them with B‐band surface brightness profiles. As a result we obtain mass‐to‐light ratio profiles. We give some arguments for why our approach is reliable and sometimes better than those assuming ad hoc the presence of a massive non‐baryonic dark matter halo. Using this model, we study galaxies NGC 7793, 1365, 6946 and UGC 6446. Based on a rotation curve from The H i Nearby Galaxy Survey (THINGS) we also study galaxy NGC 4536 and compare the results with those we published elsewhere for the same galaxy.

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“…The kinematic data seem to indicate a declining rotation curve, but the galaxy is heavily perturbed there as seen on recent deep optical images, and recent KAT-7 HI data show the presence of extraplanar cold gas (Lucero et al 2015). Earlier Hα observations of the Sculptor group galaxy NGC 7793 with the same instrument (Dicaire et al 2008) led to the conclusion that the ionizing sources of the Hα disk of this galaxy are likely to be internal, rather than the UV background.…”

Section: The Relation Between Hi Extent and The Optical Radiusmentioning

confidence: 93%

Hi in the Outskirts of Nearby Galaxies

Bosma

2017

Astrophysics and Space Science Library

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The HI in disk galaxies frequently extends beyond the optical image, and can trace the dark matter there. I briefly highlight the history of high spatial resolution HI imaging, the contribution it made to the dark matter problem, and the current tension between several dynamical methods to break the disk-halo degeneracy. I then turn to the flaring problem, which could in principle probe the shape of the dark halo. Instead, however, a lot of attention is now devoted to understanding the role of gas accretion via galactic fountains. The current Λ cold dark matter theory has problems on galactic scales, such as the core-cusp problem, which can be addressed with HI observations of dwarf galaxies. For a similar range in rotation velocities, galaxies of type Sd have thin disks, while those of type Im are much thicker. After a few comments on modified Newtonian dynamics and on irregular galaxies, I close with statistics on the HI extent of galaxies.

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DEEP FABRY-PEROT Hα OBSERVATIONS OF NGC 7793: A VERY EXTENDED Hα DISK AND a TRULY DECLINING ROTATION CURVE

Cited by 35 publications

References 57 publications

Falling Outer Rotation Curves of Star-forming Galaxies at 0.6 ≲ z ≲ 2.6 Probed with KMOS^3D and SINS/zC-SINF

Falling Outer Rotation Curves of Star-forming Galaxies at 0.6 ≲ z ≲ 2.6 Probed with KMOS^3D and SINS/zC-SINF

Global disc models for galaxies NGC 1365, 6946, 7793 and UGC 6446

Hi in the Outskirts of Nearby Galaxies

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DEEP FABRY-PEROT Hα OBSERVATIONS OF NGC 7793: A VERY EXTENDED Hα DISK AND a TRULY DECLINING ROTATION CURVE

Cited by 35 publications

References 57 publications

Falling Outer Rotation Curves of Star-forming Galaxies at 0.6 ≲ z ≲ 2.6 Probed with KMOS3D and SINS/zC-SINF

Falling Outer Rotation Curves of Star-forming Galaxies at 0.6 ≲ z ≲ 2.6 Probed with KMOS3D and SINS/zC-SINF

Global disc models for galaxies NGC 1365, 6946, 7793 and UGC 6446

Hi in the Outskirts of Nearby Galaxies

Contact Info

Product

Resources

About

Falling Outer Rotation Curves of Star-forming Galaxies at 0.6 ≲ z ≲ 2.6 Probed with KMOS^3D and SINS/zC-SINF

Falling Outer Rotation Curves of Star-forming Galaxies at 0.6 ≲ z ≲ 2.6 Probed with KMOS^3D and SINS/zC-SINF