POWERFUL H<sub>2</sub>LINE COOLING IN STEPHAN's QUINTET. I. MAPPING THE SIGNIFICANT COOLING PATHWAYS IN GROUP-WIDE SHOCKS

Cluver, Michelle; Appleton, P. N.; Boulanger, F.; Guillard, P.; Ogle, Patrick; Duc, Pierre Alain; Lu, N.; Rasmussen, Jesper; Reach, W. T.; Smith, J. D.; Tuffs, R.; Xu, C. K.; Yun, Min S.

doi:10.1088/0004-637x/710/1/248

Cited by 95 publications

(232 citation statements)

References 67 publications

Supporting

Mentioning

214

Contrasting

Order By: Relevance

“…The pixel sizes are 1.8 , 2.45 , and 5 at 16, 24, and 70 μm, respectively. Except for the 70 μm image, we direct the reader to Cluver et al (2010) for a description of the observational details and data reduction. The upper right panel of Fig.…”

Section: Spitzer Ir Imaging and Spectroscopymentioning

confidence: 99%

“…Observations with the infrared spectrograph (IRS, Houck et al 2004) onboard the Spitzer Space Telescope have revealed a powerful mid-infrared (mid-IR) H 2 rotational line emission from warm (∼10 2 −10 3 K) molecular gas in the SQ shock (Appleton et al 2006;Cluver et al 2010). The H 2 emission is extended not only over the whole ridge, but in several other structures, including an extension towards the Seyfert galaxy NGC 7319, and the intergalactic starburst SQ-A (Xu et al 1999).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Observations and modeling of the dust emission from the H₂-bright galaxy-wide shock in Stephan's Quintet

Guillard

Boulanger²,

Cluver

et al. 2010

A&A

Self Cite

View full text Add to dashboard Cite

Context. Spitzer Space Telescope observations have detected powerful mid-infrared (mid-IR) H 2 rotational line emission from the X-ray emitting large-scale shock (∼15 × 35 kpc 2 ) associated with a galaxy collision in Stephan's Quintet (SQ). Because H 2 forms on dust grains, the presence of H 2 is physically linked to the survival of dust, and we expect some dust emission to originate in the molecular gas. Aims. To test this interpretation, IR observations and dust modeling are used to identify and characterize the thermal dust emission from the shocked molecular gas. Methods. The spatial distribution of the IR emission allows us to isolate the faint PAH and dust continuum emission associated with the molecular gas in the SQ shock. We model the spectral energy distribution (SED) of this emission, and fit it to Spitzer observations. The radiation field is determined with GALEX UV, HST V-band, and ground-based near-IR observations. We consider two limiting cases for the structure of the H 2 gas: it is either diffuse and penetrated by UV radiation, or fragmented into clouds that are optically thick to UV. Results. Faint PAH and dust continuum emission are detected in the SQ shock, outside star-forming regions. The 12/24 μm flux ratio in the shock is remarkably close to that of the diffuse Galactic interstellar medium, leading to a Galactic PAH/VSG abundance ratio. However, the properties of the shock inferred from the PAH emission spectrum differ from those of the Galaxy, which may be indicative of an enhanced fraction of large and neutrals PAHs. In both models (diffuse or clumpy H 2 gas), the IR SED is consistent with the expected emission from dust associated with the warm (>150 K) H 2 gas, heated by a UV radiation field of intensity comparable to that of the solar neighborhood. This is in agreement with GALEX UV observations that show that the intensity of the radiation field in the shock is G UV = 1.4 ± 0.2 [Habing units].Conclusions. The presence of PAHs and dust grains in the high-speed (∼1000 km s −1 ) galaxy collision suggests that dust survives. We propose that the dust that survived destruction was in pre-shock gas at densites higher than a few 0.1 cm −3 , which was not shocked at velocities larger than ∼200 km s −1 . Our model assumes a Galactic dust-to-gas mass ratio and size distribution, and current data do not allow us to identify any significant deviations of the abundances and size distribution of dust grains from those of the Galaxy. Our model calculations show that far-IR Herschel observations will help in constraining the structure of the molecular gas, and the dust size distribution, and thereby to look for signatures of dust processing in the SQ shock.

show abstract

Section: Spitzer Ir Imaging and Spectroscopymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Observations and modeling of the dust emission from the H₂-bright galaxy-wide shock in Stephan's Quintet

Guillard

Boulanger²,

Cluver

et al. 2010

A&A

Self Cite

View full text Add to dashboard Cite

show abstract

“…The best studied example is Stephan's Quintet (SQ = HCG92), where HI and molecular studies show that almost all of the cold interstellar medium (ISM) now resides in the intragroup medium (Williams et al 2002;Gao & Xu 2000;Guillard et al 2012). Strong dissipative processes, in addition to gravity, are clearly at work on a large scale in this system, leading to extensive shock heating in the interfaces between galaxies and the intragroup medium, as is evident by the presence of hot X-ray gas, warm molecular hydrogen, and diffuse ionized carbon (Trinchieri et al 2005;O'Sullivan et al 2009;Appleton et al 2006;Cluver et al 2010;Appleton et al 2013).…”

Section: Introductionmentioning

confidence: 98%

Herschelobservations of Hickson compact groups of galaxies: Unveiling the properties of cold dust

Bitsakis

Charmandaris

Appleton

et al. 2014

A&A

Self Cite

View full text Add to dashboard Cite

We present a Herschel far-infrared and sub-millimetre (sub-mm) study of a sample of 120 galaxies in 28 Hickson compact groups (HCGs). Fitting their UV to sub-mm spectral energy distributions with the model of da Cunha et al. (2008), we accurately estimate the dust masses, luminosities, and temperatures of the individual galaxies. We find that nearly half of the late-type galaxies in dynamically "old" groups, those with more than 25% of early-type members and redder UV-optical colours, also have significantly lower dustto-stellar mass ratios compared to those of actively star-forming galaxies of the same mass found both in HCGs and in the field. Examining their dust-to-gas mass ratios, we conclude that dust was stripped out of these systems as a result of the gravitational and hydrodynamic interactions, experienced owing to previous encounters with other group members. About 40% of the early-type galaxies (mostly lenticulars), in dynamically "old" groups, display dust properties similar to those of the UV-optical red late-type galaxies. Given their stellar masses, star formation rates, and UV-optical colours, we suggest that red late-type and dusty lenticular galaxies represent transition populations between blue star-forming disk galaxies and quiescent early-type ellipticals. On the other hand, both the complete absence of any correlation between the dust and stellar masses of the dusty ellipticals and their enhanced star formation activity, suggest the increase in their gas and dust content due to accretion and merging. Our deep Herschel observations also allow us to detect the presence of diffuse cold intragroup dust in 4 HCGs. We also find that the fraction of 250 μm emission that is located outside of the main bodies of both the red late-type galaxies and the dusty lenticulars is 15−20% of their integrated emission at this band. All these findings are consistent with an evolutionary scenario in which gas dissipation, shocks, and turbulence, in addition to tidal interactions, shape the evolution of galaxies in compact groups.

show abstract

“…Powerful high-velocity dispersion molecular hydrogen is associated with the intergalactic shock wave (Appleton et al 2006;Guillard et al 2009). About 5 × 10 8 M of warm H 2 spread over ∼480 kpc 2 were found in the main shock region (Cluver et al 2010). In addition, CO(1−0), (2−1) and (3−2) line emission have been detected in this region with complex profiles, spanning a velocity range ∼1000 km s −1 (Guillard et al 2012).…”

Section: Introductionmentioning

confidence: 99%

A dynamical model for the Taffy galaxies UGC 12914/5

Vollmer¹,

Braine²,

Soida³

2012

A&A

View full text Add to dashboard Cite

The spectacular head-on collision of the two gas-rich galaxies of the Taffy system, UGC 12914/15, gives us a unique opportunity to study the consequences of a direct ISM-ISM collision. To interpret existing multi-wavelength observations, we made dynamical simulations of the Taffy system including a sticky particle component. To compare simulation snapshots to Hi and CO observations, we assume that the molecular fraction of the gas depends on the square root of the gas volume density. For the comparison of our simulations with observations of polarized radio continuum emission, we calculated the evolution of the 3D large-scale magnetic field for our simulations. The induction equations including the time-dependent gas-velocity fields from the dynamical model were solved for this purpose. Our simulations reproduce the stellar distribution of the primary galaxy, UGC 12914, the prominent Hi and CO gas bridge, the offset between the CO and Hi emission in the bridge, the bridge isovelocity vectors parallel to the bridge, the Hi double-line profiles in the bridge region, the large line-widths (∼200 km s −1 ) in the bridge region, the high field strength of the bridge large-scale regular magnetic field, the projected magnetic field vectors parallel to the bridge and the strong total power radio continuum emission from the bridge. The stellar distribution of the secondary model galaxy is more perturbed than observed. The observed distortion of the Hi envelope of the Taffy system is not reproduced by our simulations which use initially symmetric gas disks. The model allows us to define the bridge region in three dimensions. We estimate the total bridge gas mass (Hi, warm and cold H 2 ) to be 5 to 6× 10 9 M , with a molecular fraction M H 2 /M HI of about unity. Despite the enormous mass of molecular gas in the bridge, very little star formation is present, similar to other systems with extraplanar gas and broad CO lines. The structure of the model gas bridge is bimodal: on kpc-scales there is a dense ( 0.01 M pc −3 ) component with a high velocity dispersion >100 km s −1 and a less dense (∼10 −3 M pc −3 ) component with a smaller, but still high, velocity dispersion ∼50 km s −1 . The synchrotron lifetime of relativistic electrons is only long enough to be consistent with the existence of the radio continuum bridge for the less dense component. On the other hand, only the high-density gas undergoes a high enough mechanical energy input to produce the observed strong emission of warm H 2 . We propose that, despite the high local gas densities, this high input of mechanical energy drives strong turbulence and quenches star formation in the bridge gas except for the giant Hii region near UGC 12915. Our model suggests that we observe this galaxy head-on collision near the time of maximum CO and H 2 emission.

show abstract

POWERFUL H₂LINE COOLING IN STEPHAN's QUINTET. I. MAPPING THE SIGNIFICANT COOLING PATHWAYS IN GROUP-WIDE SHOCKS

Cited by 95 publications

References 67 publications

Observations and modeling of the dust emission from the H₂-bright galaxy-wide shock in Stephan's Quintet

Observations and modeling of the dust emission from the H₂-bright galaxy-wide shock in Stephan's Quintet

Herschelobservations of Hickson compact groups of galaxies: Unveiling the properties of cold dust

A dynamical model for the Taffy galaxies UGC 12914/5

Contact Info

Product

Resources

About

POWERFUL H2LINE COOLING IN STEPHAN's QUINTET. I. MAPPING THE SIGNIFICANT COOLING PATHWAYS IN GROUP-WIDE SHOCKS

Cited by 95 publications

References 67 publications

Observations and modeling of the dust emission from the H2-bright galaxy-wide shock in Stephan's Quintet

Observations and modeling of the dust emission from the H2-bright galaxy-wide shock in Stephan's Quintet

Herschelobservations of Hickson compact groups of galaxies: Unveiling the properties of cold dust

A dynamical model for the Taffy galaxies UGC 12914/5

Contact Info

Product

Resources

About

POWERFUL H₂LINE COOLING IN STEPHAN's QUINTET. I. MAPPING THE SIGNIFICANT COOLING PATHWAYS IN GROUP-WIDE SHOCKS

Observations and modeling of the dust emission from the H₂-bright galaxy-wide shock in Stephan's Quintet

Observations and modeling of the dust emission from the H₂-bright galaxy-wide shock in Stephan's Quintet