Star formation in southern Seyfert galaxies

Forbes, Duncan A.; Norris, R. P.

doi:10.1046/j.1365-8711.1998.01940.x

Cited by 23 publications

(52 citation statements)

References 29 publications

(38 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Strickland (2007) concluded that NGC 6810 is in fact a "full disk" superwind galaxy and that the previous classification is based largely on misidentification of counterparts in a low resolution radio survey and the merged line profiles of an outflowing wind. This is compatible with the earlier observation (Forbes & Norris 1998) that the radio, FIR, and [Fe ii] properties of the inner disk are ) shows striking evidence for an "ionization cone" on the near side of the disk. These structures are not unique to AGN sources (e.g., Pogge & Eskridge 1987;Tadhunter & Tsvetanov 1989) having been observed in starburst galaxies (e.g., Shopbell & Bland-Hawthorn 1998).…”

Section: Ngc 6810supporting

confidence: 92%

See 1 more Smart Citation

THREE-DIMENSIONAL INTEGRAL FIELD OBSERVATIONS OF 10 GALACTIC WINDS. I. EXTENDED PHASE (≳10 Myr) OF MASS/ENERGY INJECTION BEFORE THE WIND BLOWS

Sharp

Bland-Hawthorn

2010

ApJ

244

282

View full text Add to dashboard Cite

In recent years, we have come to recognize the widespread importance of large-scale winds in the life cycle of galaxies. The onset and evolution of a galactic wind is a highly complex process which must be understood if we are to understand how energy and metals are recycled throughout the galaxy and beyond. Here we present three-dimensional spectroscopic observations of a sample of 10 nearby galaxies with the AAOmega-SPIRAL integral-field spectrograph on the 3.9 m Anglo-Australian Telescope, the largest survey of its kind to date. The double-beam spectrograph provides spatial maps in a range of spectral diagnostics:, 6731. We demonstrate that these flows can often separate into highly ordered structures through the use of ionization diagnostics and kinematics. All of the objects in our survey show extensive wind-driven filamentation along the minor axis, in addition to large-scale disk rotation. Our sample can be divided into either starburst galaxies or active galactic nuclei (AGNs), although some objects appear to be a combination of these. The total ionizing photon budget available to both classes of galaxies is sufficient to ionize all of the windblown filamentation out to large radius. We find, however, that while AGN photoionization always dominates in the wind filaments, this is not the case in starburst galaxies where shock ionization dominates. This clearly indicates that after the onset of star formation, there is a substantial delay ( 10 Myr) before a starburst wind develops. We show why this behavior is expected by deriving "ionization" and dynamical timescales for both AGNs and starbursts. We establish a sequence of events that lead to the onset of a galactic wind. The clear signature provided by the ionization timescale is arguably the strongest evidence yet that the starburst phenomenon is an impulsive event. A well-defined ionization timescale is not expected in galaxies with a protracted history of circumnuclear star formation. Our three-dimensional data provide important templates for comparisons with high-redshift galaxies.

show abstract

Section: Ngc 6810supporting

confidence: 92%

“…Sandqvist et al 1995). The radio/far-IR ratio is also indicative of a dominant circumnuclear starburst (Forbes & Norris 1998). The extended ionized gas in NGC 1365 has been extensively studied with long-slit spectroscopy.…”

Section: Agn 321 Ngc 1365mentioning

confidence: 99%

THREE-DIMENSIONAL INTEGRAL FIELD OBSERVATIONS OF 10 GALACTIC WINDS. I. EXTENDED PHASE (≳10 Myr) OF MASS/ENERGY INJECTION BEFORE THE WIND BLOWS

Sharp

Bland-Hawthorn

2010

ApJ

244

282

View full text Add to dashboard Cite

show abstract

“…Radio continuum observations of NGC 1365 using the ATCA have been presented by Forbes & Norris (1998). Radio maps were obtained at 3 and 6 cm giving an effective resolution of ∼1 arcsec and ∼2 arcsec respectively.…”

Section: Radio Observations Of Ngc 1365mentioning

confidence: 99%

“…The cone is also aligned with a suggested radio jet (Sandqvist, Jörsäter & Lindblad 1995), although we shall discuss the nature of this jet in more detail later. Radio observations of NGC 1365 by Saikia et al (1994), Sandqvist et al (1995) and Forbes & Norris (1998) reveal a complex, possibly ring‐like structure around the nucleus, but with several radio hotspots loosely coincident with the giant H II regions.…”

Section: Introductionmentioning

confidence: 97%

See 1 more Smart Citation

The complex radio and X-ray structure in the nuclear regions of the active galaxy NGC 1365

Stevens¹,

Forbes²,

Norris³

1999

Monthly Notices of the Royal Astronomical Society

Self Cite

View full text Add to dashboard Cite

We present a multiwavelength analysis of the prominent active galaxy NGC 1365, in particular looking at the radio and X‐ray properties of the central regions of the galaxy. We analyse ROSAT (PSPC and HRI) observations of NGC 1365, and discuss recent ASCA results. In addition to a number of point sources in the vicinity of NGC 1365, we find a region of extended X‐ray emission extending along the central bar of the galaxy, combined with an emission peak near the centre of the galaxy. This central X‐ray emission is centred on the optical/radio nucleus, but is spatially extended. The X‐ray spectrum can be well fitted by a thermal plasma model, with a temperature of kT=0.6–0.8 keV and a very low local absorbing column. The thermal spectrum is suggestive of starburst emission rather than emission from a central black hole. The ATCA radio observations show a number of hotspots, located in a ring around a weak radio nucleus. Synchrotron emission from electrons accelerated by supernovae and supernova remnants (SNRs) is the likely origin of these hotspots. The radio nucleus has a steep spectrum, indicative perhaps of an active galactic nucleus (AGN) or SNRs. The evidence for a jet emanating from the nucleus (as has been previously claimed) is at best marginal. The extent of the radio ring is comparable to that of the extended central X‐ray source. We discuss the nature of the central activity in NGC 1365 in the light of these observations. The extended X‐ray emission and the thermal spectra strongly suggest that at soft X‐ray energies we are not seeing emission predominantly from a central black hole, although the presence of Fe K line emission at higher energies does suggest the presence of an AGN. Consequently, a black hole is probably not the dominant contributor to the energetics of the central regions of NGC 1365 at radio, optical or soft X‐ray wavelengths. Activity associated with a starburst is likely the dominant explanation for the observed properties of NGC 1365.

show abstract

Constraints on the nuclear emission of the Circinus galaxy: the torus

Ruiz

Efstathiou

Alexander

et al. 2001

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

A B S T R A C TIn the context of the unified model of Seyfert galaxies, we use observations from the literature and a radiative transfer model to investigate the near-IR to mm emission produced by the presumed torus in the Circinus galaxy, from 2 mm to 1.3 mm. From the infrared SED modelling, we find that the total luminosity (L IR ) in this wavelength range consists of similar contributions from the torus and starburst with a ratio of nuclear luminosity to starburst luminosity ðL NUC =L SB Þ , 0:8.By using a similar torus model to that of NGC 1068, but without the conical dust, we find an upper limit to the outer torus radius of ,12 pc with a best fit of ,2 pc. The upper limit torus size estimated from the radiative transfer modelling is consistent with the 16-pc torus radius estimated from near-IR imaging polarimetry of Circinus.

show abstract

Star formation in southern Seyfert galaxies

Cited by 23 publications

References 29 publications

THREE-DIMENSIONAL INTEGRAL FIELD OBSERVATIONS OF 10 GALACTIC WINDS. I. EXTENDED PHASE (≳10 Myr) OF MASS/ENERGY INJECTION BEFORE THE WIND BLOWS

THREE-DIMENSIONAL INTEGRAL FIELD OBSERVATIONS OF 10 GALACTIC WINDS. I. EXTENDED PHASE (≳10 Myr) OF MASS/ENERGY INJECTION BEFORE THE WIND BLOWS

The complex radio and X-ray structure in the nuclear regions of the active galaxy NGC 1365

Constraints on the nuclear emission of the Circinus galaxy: the torus

Contact Info

Product

Resources

About