Large-scale HI in nearby radio galaxies: segregation in neutral gas content with radio source size

Emonts, B.; Morganti, Raffaella; Oosterloo, Thomas; Hulst, van der Thijs; Moorsel, G. van; Tadhunter, C. N.

doi:10.1051/0004-6361:20066159

Cited by 24 publications

(51 citation statements)

References 31 publications

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“…A stellar population analysis of Emonts (2006) also suggests that the last interaction (that caused a burst of star formation) occured at least one to several Gyr ago, but this starburst may be the result of a smaller accretion event and is no evidence for a major merger.…”

Section: Accretion Of Small Gas Clumpsmentioning

confidence: 99%

Cold gas in massive early-type galaxies: the case of NGC 1167

Struve

Oosterloo

Sancisi

et al. 2010

A&A

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We present a study of the morphology and kinematics of the neutral hydrogen in the gas-rich (M HI = 1.5 × 10 10 M ), massive earlytype galaxy NGC 1167, which was observed with the Westerbork Synthesis Radio Telescope (WSRT). The H i is located in a 160 kpc disk (≈3 × D 25 ) and has low surface density (≤2 M pc −2 ). The disk shows regular rotation for r < 65 kpc but several signs of recent and ongoing interaction and merging with fairly massive companions are observed. No population of cold gas clouds is observed -in contrast to what is found in some spiral galaxies. This suggests that currently the main mechanism bringing in cold gas to the disk is the accretion of fairly massive satellite galaxies, rather than the accretion of a large number of small gas clumps. NGC 1167 is located in a (gas-) rich environment: we detect eight companions with a total H i mass of ∼6 × 10 9 M within a projected distance of 350 kpc. Deep optical images show a disrupted satellite at the northern edge of the H i disk. The observed rotation curve shows a prominent bump of about 50 km s −1 (in the plane of the disk) at r ≈ 1.3 × R 25 . This feature in the rotation curve occurs at the radius where the H i surface density drops significantly and may be due to large-scale streaming motions in the disk. We suspect that both the streaming motions and the H i density distribution are the result of the interaction/accretion with the disrupted satellite. Like in other galaxies with wiggles and bumps in the rotation curve, H i scaling describes the observed rotation curve best. We suggest that interactions create streaming motions and features in the H i density distribution and that this is the reason for the success of H i scaling in fitting such rotation curves.

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Section: Accretion Of Small Gas Clumpsmentioning

confidence: 99%

Cold gas in massive early-type galaxies: the case of NGC 1167

Struve

Oosterloo

Sancisi

et al. 2010

A&A

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“…Similar to the sample of early-type galaxies, a variety of Hi structures is found for the radio galaxies, including (settling) disk structures. However, the striking result from this analysis is that large amounts of Hi, rotating in regular disks, are only detected around compact sources (typically <10 kpc, Emonts et al 2007). Extended radio sources -comparable to Cen A -do only show modest amounts of Hi (few times 10 8 M ) (Figure 4; see also Emonts et al 2007).…”

Section: Comparison With Other Radio Galaxiesmentioning

confidence: 90%

“…The reason for the slightly lower detection rate (compared to radio-quiet early-type galaxies, >50%) is that the upper Hi mass limits of the non-detections are higher. Therefore, the difference is believed to be the result of observational limitations and not to be an intrinsic feature of radio galaxies (Emonts 2006;B. H. C. Emonts et al in prep.).…”

Section: Comparison With Other Radio Galaxiesmentioning

confidence: 97%

“…García-Ruiz et al 2002). Most Figure 3 Distances of the radio sources of the complete sample of nearby radio galaxies (Emonts 2006;B. H. C. Emonts et al in prep.).…”

Section: Comparison With Other Early-type Galaxiesmentioning

confidence: 99%

“…This makes Cen A a unique object only because it can be observed in great detail as it is much closer to us than any other radio source with comparable radio luminosity. Figure 3 shows the distances of a complete sample of nearby low-luminosity radio sources (Emonts 2006;B. H. C. Emonts et al in prep.).…”

Section: Comparison With Other Radio Galaxiesmentioning

confidence: 99%

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Is Centaurus A Special? A Neutral-Hydrogen Perspective

Struve

Morganti

Oosterloo

et al. 2010

Publ. – Astron. Soc. Aust

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Due to its proximity, the neutral hydrogen belonging to Cen A can be observed at high resolution with good sensitivity. This allows us to study the morphology and kinematics in detail, in order to understand the evolution of this radio-loud source (e.g. merger history, AGN activity). At the same time, it is important to compare results to other sources of the same class (i.e. early-type galaxies in general and radio galaxies in particular) to see how Cen A fits into the global picture of early-type/radio galaxy evolution. The amount of Hi, the morphology of a warped disk with Hi clouds surrounding the disk and the regular kinematics of the inner part of the Hi disk are not unusual for early-type galaxies. The growing evidence that mergers are not necessarily responsible for AGN activity fits with the observational result that the recent merger event in Cen A is not directly connected to the current phase of activity. Based on these results, we conclude that Cen A has typical neutral hydrogen properties for an early-type and radio galaxy and it can therefore -from the perspective of Hi -be seen as a typical example of its class.

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Gas and stars in compact (young) radio sources

et al. 2009

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Gas can be used to trace the formation and evolution of galaxies as well as the impact that the nuclear activity has on the surrounding medium. For nearby compact radio sources, we have used observations of neutral hydrogen -that we detected in emission distributed over very large scales -combined with the study of the stellar population and deep optical images to investigate the history of the formation of their host galaxy and the triggering of the activity. For more distant and more powerful compact radio sources, we have used optical spectra and H I -in absorption -to investigate the presence of fast outflows that support the idea that compact radio sources are young radio loud AGN observed during the early stages of their evolution and currently shredding their natal cocoons through extreme circumnuclear outflows. We will review the most recent results obtained from these projects.

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Large-scale HI in nearby radio galaxies: segregation in neutral gas content with radio source size

Cited by 24 publications

References 31 publications

Cold gas in massive early-type galaxies: the case of NGC 1167

Cold gas in massive early-type galaxies: the case of NGC 1167

Is Centaurus A Special? A Neutral-Hydrogen Perspective

Gas and stars in compact (young) radio sources

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