Discovery of Neutral Hydrogen Associated with the Diffuse Shells of NGC 5128 (Centaurus A)

Schiminovich, David; Vangorkom, Jh; Vanderhulst, Jm; Kasow, Steve

doi:10.1086/187246

Cited by 192 publications

(254 citation statements)

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“…The cloud locations may be associated with some of the stellar shells (Schiminovich et al 1994). Richter, Sackett, & Sparke (1994) found the mass of H I clouds around Cen A to be 7.8 ] 108 ] (1.0^0.3) Schiminovich et al (1994) found an H I M _ . mass of 4.5 ] 108 in the disk and 1.5 ] 108 in the M _ M _ shells, peaking at a projected distance 15 kpc from the nucleus.…”

Section: Previous Observationsmentioning

confidence: 99%

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The Centaurus A Northern Middle Lobe as a Buoyant Bubble

Saxton

Sutherland

Bicknell

2001

ApJ

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We model the northern middle radio lobe of Centaurus A (NGC 5128) as a buoyant bubble of plasma deposited by an intermittently active jet. The extent of the rise of the bubble and its morphology imply that the ratio of its density to that of the surrounding ISM is less than 10~2, consistent with our knowledge of extragalactic jets and minimal entrainment into the precursor radio lobe. Using the morphology of the lobe to date the beginning of its rise through the atmosphere of Cen A, we conclude that the bubble has been rising for approximately 140 Myr. This timescale is consistent with that proposed by Quillen and coworkers for the settling of postmerger gas into the presently observed large-scale disk in NGC 5128, suggesting a strong connection between the delayed reestablishment of radio emission and the merger of NGC 5128 with a small gas-rich galaxy. This suggests a connection, for radio galaxies in general, between mergers and the delayed onset of radio emission. In our model, the elongated X-ray emission region discovered by Feigelson and coworkers, part of which coincides with the northern middle lobe, is thermal gas that originates from the interstellar medium below the bubble and that has been uplifted and compressed. The "" large-scale jet ÏÏ appearing in the radio images of Morganti and coworkers may be the result of the same pressure gradients that cause the uplift of the thermal gas, acting on much lighter plasma, or may represent a jet that did not turn o † completely when the northern middle lobe started to buoyantly rise. We propose that the adjacent emission-line knots (the "" outer Ðlaments ÏÏ) and star-forming regions result from the disturbance, in particular the thermal trunk, caused by the bubble moving through the extended atmosphere of NGC 5128.

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Section: Previous Observationsmentioning

confidence: 99%

“…within the span of the disk and M _ the estimate of 2 ] 1011 within 15 kpc by Schiminovich M _ et al (1994) from velocity measurements of the H I shells, assuming circular motion. Kinematic studies of the planetary nebulae (Hui et al 1995 ;Mathieu, Dejonghe, & Hui 1996) Cen A possesses radio-emitting features on diverse scales.…”

Section: Previous Observationsmentioning

confidence: 99%

The Centaurus A Northern Middle Lobe as a Buoyant Bubble

Saxton

Sutherland

Bicknell

2001

ApJ

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“…Such a case has been detected in the nearby giant elliptical galaxy Centaurus A, where ∼15 K dust has been detected outside the main body of the galaxy (see Stickel et al 2004). This was understood as a consequence of the accretion by a number of gas-rich dwarf companion galaxies that surround Centaurus A and have led to the formation of its dust lane, as well as to the filaments of atomic and molecular gas that surrounds it (see Schiminovich et al 1994;Charmandaris et al 2000). Based on our Spitzer data, warm dust in the intragroup environment has been seen in some groups (HCG40,54,55,and 79) in the form of diffuse mid-IR light or an extended halo around groups members.…”

Section: Cold Dust In Hickson Compact Groupsmentioning

confidence: 99%

A mid-IR study of Hickson compact groups

Bitsakis¹,

Charmandaris

Floc’h

et al. 2010

A&A

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Hickson compact groups (HCGs) are among the densest galaxy environments of the local universe. To examine the effects of the environment on the infrared properties of these systems, we present an analysis of Spitzer and ISO mid-infrared imaging, as well as of deep ground-based near-infrared imaging of 14 HCGs containing a total of 69 galaxies. Based on mid-infrared color diagnostics we identify the galaxies that appear to host an active nucleus, while using a suite of templates, and fit the complete infrared spectral energy distribution for each group member. We compare our estimates of galaxy mass, star formation rate, total infrared luminosities, and specific star formation rates (sSFR) for our HCG sample to samples of isolated galaxies and interacting pairs and find that overall there is no discernible difference among them. However, HCGs that can be considered as dynamically "old" host late-type galaxies with a slightly lower sSFR than the one found in dynamically "young" groups. This could be attributed to multiple past interactions among the galaxies in old groups, that have led to the build up of their stellar mass. It is also consistent with our prediction of the presence of diffuse cold dust in the intergalactic medium of 9 of the dynamically "old" groups.

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“…With the sensitivity of present day radio telescopes it is very difficult to detect neutral hydrogen in emission at the typical distance of radio galaxies. HI in emission is detected only in an handful of very nearby radio galaxies, for example IC 1459 (Oosterloo et al 1999), NGC 4278 (Raimond et al 1981Lees 1994), NGC 1052(van Gorkom et al 1986), PKS B1718-649 (Véron-Cetty et al 1995) and Centaurus A (van Gorkom et al 1990;Schiminovich et al 1994). With the exception of the last two objects, these radio sources are at the lower end of the distribution of radio power for radio galaxies and they are more than an order of magnitude less powerful than B2 0648+27.…”

Section: Gas Disks and Radio Activitymentioning

confidence: 99%

B2 0648+27: A radio galaxy in a major merger

Morganti¹,

Oosterloo²,

Capetti

et al. 2003

A&A

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Abstract. We present WSRT observations of the neutral hydrogen in the nearby radio galaxy B2 0648+27. In emission, we detect a very large amount of HI (M HI = 1.1 × 10 10 M ) that is distributed in a very extended disk, or ring-like structure, of about 160 kpc in size. We also detect HI absorption against the central radio continuum component. The detection of the HI, its structure and kinematics, give us key information for building a possible evolutionary scenario. The characteristics of the detected HI are explained as the result of a major merger event that is likely to have occurred < ∼ 10 9 yr ago. Interestingly, we find that, when observed in radio continuum at higher resolution, this galaxy has a double lobed, steep spectrum structure of about 1 kpc in size. Thus, despite its low radio power, B2 0648+27 bears striking similarities with Compact Symmetric Objects, i.e. objects believed to represent the early phase of radio galaxies ( < ∼ few thousand yrs old). B2 0648+27 is one of the few nearby radio galaxies where extended neutral hydrogen has been detected so far. This, and other recent results, appear however to indicate that nearby radio galaxies are more often gas rich than commonly assumed. The phenomena described are likely to be much more common at high redshift and galaxies like B2 0648+27 may provide valuable information on the evolution of high redshift radio sources.

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Discovery of Neutral Hydrogen Associated with the Diffuse Shells of NGC 5128 (Centaurus A)

Cited by 192 publications

References 0 publications

The Centaurus A Northern Middle Lobe as a Buoyant Bubble

The Centaurus A Northern Middle Lobe as a Buoyant Bubble

A mid-IR study of Hickson compact groups

B2 0648+27: A radio galaxy in a major merger

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