The apparent “reversed” motion of gas and stars in M 82

Greve, A.

doi:10.1051/0004-6361/201016069

Cited by 3 publications

(6 citation statements)

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“…Toward E2, several velocity components are detected in the H(41)α and molecular lines. All these components are within the range of velocities of the x2 bar orbits, ±120 km s −1 (Greve 2011). The component at ∼260 km s −1 is the most intense in molecular emission and is detected in CN, N 2 H + , and CS.…”

Section: Vertical Distribution Of the Molecular Emissionmentioning

confidence: 82%

Chemical footprint of star formation feedback in M 82 on scales of ~100 pc

Ginard

Fuente

García‐Burillo

et al. 2015

A&A

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Context. M 82 is one of the nearest and brightest starburst galaxies. It has been extensively studied in the past decade and by now is considered the prototypical extragalactic photon-dominated region (PDR) and a reference for studying star formation feedback. Aims. Our aim is to characterize the molecular chemistry in M 82 at spatial scales of giant molecular clouds (GMCs), ∼100 pc, to investigate the feedback effects of the star formation activity. Methods. We present interferometric observations of the CN 1 → 0 (113.491 GHz), N 2 H + 1 → 0 (93.173 GHz), H (41) + ] ratio can be explained as the consequence of differences in the local intestellar UV field and in the average cloud sizes within the nucleus of the galaxy. Conclusions. Our high spatial resolution imaging of the starburst galaxy M 82 shows that the star formation activity has a strong impact on the chemistry of the molecular gas. In particular, the entire nucleus behaves as a giant PDR whose chemistry is determined by the local UV flux. The detection of N 2 H + shows the existence of a population of clouds with A v > 20 mag all across the galaxy plane. These clouds constitute the molecular gas reservoir for the formation of new stars and, although it is distributed throughout the nucleus, the highest concentration occurs in the outer x1 bar orbits (R ∼ 280 pc).

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Section: Vertical Distribution Of the Molecular Emissionmentioning

confidence: 82%

Chemical footprint of star formation feedback in M 82 on scales of ~100 pc

Ginard

Fuente

García‐Burillo

et al. 2015

A&A

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“…Our data contain evidence of a "velocity reversal" (velocity decrease) at ∼1.0 kpc on both the eastern and western sides of the galaxy. Greve (2011) highlights the existence of a 100 km s −1 velocity reversal of gas and/or stars at ∼1.0 kpc in Hδ and Hǫ stellar absorption on the eastern side of the galaxy, as well as in ionized gas emission lines at visible and blue wavelengths on the eastern and western sides; interestingly, the feature is apparently absent in near-infrared Ca II stellar absorption. Although the velocity amplitude of our detection is approximately a factor of 10 less, the reversal is present in our data.…”

Section: Rotation Curvementioning

confidence: 86%

“…Local extinction is not likely to be the culprit, as the feature is symmetric with respect to the nucleus. Greve (2011) investigates the hypothesis that the re- FIG. 4.-(a) The gas and stellar rotation curves from this work and the measurements of CO (2,1) by Sofue (1998).…”

Section: Rotation Curvementioning

confidence: 99%

“…Rotation curves are most commonly employed to determine the distribution of mass in galaxies (Sofue & Rubin 2001), and many studies have employed gas and stellar kinematics at a range of wavelengths to measure radial velocities in M82 (e.g., Saito et al 1984;Goetz et al 1990;McKeith et al 1993;Achtermann & Lacy 1995;Sofue et al 1992). Greve (2011) includes a compilation of these results. Given that M82 has recently undergone tidal interactions and harbors an extraordinary superwind, stellar kinematics should be a more reliable tracer of the mass distribution than the gas.…”

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confidence: 99%

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Measurement of the Mass and Stellar Population Distribution in M82 With the LBT

Greco

Martini

Thompson

2012

ApJ

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We present a K−band spectroscopic study of the stellar and gas kinematics, mass distribution, and stellar populations of the archetypical starburst galaxy M82. Our results are based on a single spectrum at a position angle of 67.5 • through the K−band nucleus. We used the 12 CO stellar absorption band head at 2.29 µm (CO 2.29 ) to measure the rotation curve out to nearly 4 kpc radius on both the eastern and western sides of the galaxy. Our data show that the rotation curve is flat from 1 − 4 kpc. This stands in sharp contrast to some previous studies, which have interpreted HI and CO emission-line position-velocity diagrams as evidence for a declining rotation curve. The kinematics of the Brγ, H 2 , and He I emission lines are consistent with, although characterized by slightly higher velocities than, the stellar kinematics. We derived M82's mass distribution from our stellar kinematic measurements and estimate its total dynamical mass is ∼10 10 M ⊙ . We measured the equivalent width of CO 2.29 (W 2.29 ) as a function of distance from the center of the galaxy to investigate the spatial extent of the red supergiant (RSG) population. The variation in W 2.29 with radius clearly shows that RSGs dominate the light inside 500 pc radius. M82's superwind is likely launched from this region, where we estimate the enclosed mass is 2×10 9 M ⊙ .

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“…For comparison, the prototypical superwind in M82 is known to show qualitatively similar characteristics as the one in NGC 4418 (e.g., Alton et al 1999;Heckman et al 2000;Yoshida et al 2011;Contursi et al 2013;Salak et al 2013;Leroy et al 2015; see Section 5.4 for detailed quantitative comparison). Its outflow velocity monotonically increases outward (e.g., Bland & Tully 1988;McKeith et al 1995;Shopbell & Bland-Hawthorn 1998;Greve 2004Greve , 2011 in such a way that the ionizedgas outflow is faster than those of the molecular gas, cold neutral atomic gas, and dusts (e.g., Seaquist & Clark 2001;Yoshida et al 2011;Contursi et al 2013). The cold-gas outflows are ubiquitously found by using Na D absorption line in starburst galaxies including (U)LIRGs (e.g., Rupke et al 2002;Martin 2005Martin , 2006Rupke et al 2005b;Chen et al 2010), and their outflow velocities are generally similar or slower than the ionized-gas ones (e.g., Rupke et al 2002Rupke et al , 2005b.…”

Section: Evidence For Dusty Superwindmentioning

confidence: 99%

Dusty Superwind from a Galaxy with a Compact Obscured Nucleus: Optical Spectroscopic Study of NGC 4418

Ohyama

Sakamoto

Aalto

et al. 2019

ApJ

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We report our optical spectroscopic study of the nucleus and its surrounding region of a nearby luminous infrared galaxy NGC 4418. This galaxy has been known to host a compact obscured nucleus, showing distinct characteristics such as a very compact (∼ 20 pc) sub-mm and mid-infrared core and dusty circumnuclear region with massive molecular gas concentration. We detected dusty superwind outflow at 1 kpc scale along the disk semiminor axis in both shock-heated emission lines and enhanced interstellar Na D absorption. This superwind shows basic characteristics similar to those of the prototypical superwind in the starburst galaxy M82, such as a kpc-scale extended structure of gas and dust along the disk minor axis, outflowing components (multiphase gas and dust), physical conditions of the ionized gas, and monotonically blueshifting radial velocity field with increasing distance from the nucleus on the front side of the superwind. We also detected a moderately extinct starburst population in the SDSS nuclear spectrum with the burst age of 10 Myr and stellar mass of 1 × 10 7 M . It is powerful enough to drive the superwind within the dynamical age of the superwind ( 10 Myr). On the basis of comparison between this starburst-superwind scenario and the observations in terms of the burst age, stellar mass, infrared luminosity, and obscuration in the optical bands, we argue that this superwind-driving starburst is separate from the sub-mm core even if the core is a very young star cluster. Therefore, this galaxy hosts both the enshrouded compact core and the superwind-driving circumnuclear starburst.

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The apparent “reversed” motion of gas and stars in M 82

Cited by 3 publications

References 49 publications

Chemical footprint of star formation feedback in M 82 on scales of ~100 pc

Chemical footprint of star formation feedback in M 82 on scales of ~100 pc

Measurement of the Mass and Stellar Population Distribution in M82 With the LBT

Dusty Superwind from a Galaxy with a Compact Obscured Nucleus: Optical Spectroscopic Study of NGC 4418

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