Star formation in Seyfert galaxies

Espinosa, J. M. Rodríguez; Rudy, R. J.; Jones, B.

doi:10.1086/164901

Cited by 62 publications

(30 citation statements)

References 4 publications

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“…Furthermore, our images indicate that generally the star-forming activity occurs in the vicinity of the active nucleus (within a few hundred parsecs). This supports the idea of a tight connection between starburst and AGN activity as claimed in the past by various authors based both on observational and theoretical grounds (Heckman et al 1989 ;Gonzalez Delgado et al 1998 ;Oliva et al 1999 ;Rodriguez Espinosa, Rudy, & Jones 1987 ;Norman & Scoville 1988 ;Collin & Zahn 1999).…”

Section: Extended Mir Emissionsupporting

confidence: 89%

N‐Band Imaging of Seyfert Nuclei and the Mid‐Infrared–X‐Ray Correlation

Krabbe¹,

Maiolino²

2001

ApJ

111

118

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We present new mid-infrared (N-band) images of a sample of eight nearby Seyfert galaxies. In all of our targets, we detect a central unresolved source, which in some cases has been identiÐed for the Ðrst time. In particular, we have detected the mid-infrared emission from the active nucleus of NGC 4945, which previously remained undetected at any wavelength but hard X-rays. We also detect circumnuclear extended emission in the Circinus galaxy along its major axis and Ðnd marginal evidence for extended circumnuclear emission in NGC 3281. The high spatial resolution of our data allows us to separate (1A .7) the Ñux of the nuclear point sources from the extended circumnuclear starburst (if present). We complement our sample with literature data for a number of nonactive starburst galaxies and relate the nuclear N-band Ñux to published hard (2È10 keV) X-ray Ñuxes. We Ðnd tight and well-separated correlations between the nuclear N-band Ñux and X-ray Ñux for both Seyfert and starburst nuclei that span over 3 orders of magnitude in luminosity. We demonstrate that these correlations can be used as a powerful classiÐcation tool for galactic nuclei. For example, we Ðnd strong evidence against NGC 1808 currently harboring an active Seyfert nucleus based on its position in the mid-infraredÈX-ray diagram. On the other hand, we conÐrm that NGC 4945 is in fact a Seyfert 2 galaxy.

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Section: Extended Mir Emissionsupporting

confidence: 89%

N‐Band Imaging of Seyfert Nuclei and the Mid‐Infrared–X‐Ray Correlation

Krabbe¹,

Maiolino²

2001

ApJ

111

118

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“…Rodriguez Espinosa et al 1987;Ranalli et al 2003). While the bulk of this is radiated at far-IR wavelengths (at > ∼ 60-μm), the mid-IR flux around 10-μm due to SF is far from negligible (e.g.…”

Section: Constraining Unresolved Mid-ir Star Formationmentioning

confidence: 99%

“…But isolating the AGN emission from other ubiquitous contaminating sources, such as bright starbursts within the inner few kpc of AGN host galaxies (e.g. Rodriguez Espinosa et al 1987;Norman & Scoville 1988;González Delgado et al 2001), is difficult because of the finite resolving powers of IR observatories. Telescopes with improving sensitivity, wavelength coverage, and resolving power have changed the situation steadily over the past two decades (e.g., Sanders et al 1989;Mulchaey et al 1994;Spinoglio et al 1995;Krabbe et al 2001;Lutz et al 2004;Buchanan et al 2006;Ramos Almeida et al 2007;Mushotzky et al 2008;Meléndez et al 2008;McKernan et al 2009).…”

Section: Introductionmentioning

confidence: 99%

Resolving the mid-infrared cores of local Seyferts

Gandhi

Horst

Smette

et al. 2009

A&A

394

112

647

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We present new photometry of 16 local Seyferts including 6 Compton-thick sources in N-band filters around 12-μm, obtained with the VISIR instrument on the 8-m Very Large Telescope. The near-diffraction-limited imaging provides the least-contaminated core fluxes for these sources to date. Augmenting these with our previous observations and with published intrinsic X-ray fluxes, we form a total sample of 42 sources for which we find a strong mid-infrared:X-ray (12.3 μm:2-10 keV) luminosity correlation. Performing a physically-motivated subselection of sources in which the Seyfert torus is likely to be best-resolved results in the correlation L MIR ∝ L X 1.11±0.07 , with a reduction of the scatter in luminosities as compared to the full sample. Consideration of systematics suggests a range of 1.02-1.21 for the correlation slope. The mean 2-keV:12.3-μm spectral index (α IX ) is found to be −1.10 ± 0.01, largely independent of luminosity. Indirectly-computed 12-μm bolometric corrections range over ≈10-30 if a known luminosity trend of X-ray bolometric corrections is assumed. Comparison with ISO data spanning a wider luminosity range suggests that our correlation can be extended into the quasar regime. That unobscured, obscured, and Compton-thick sources all closely follow the same luminosity correlation has important implications for the structures of Seyfert cores. The typical resolution-limit of our imaging corresponds to ∼70 pc at a median z = 0.01, and we use the tightness of the correlation to place constraints on the dominance of any residual emission sources within these physical scales. An upper-limit for any contaminating star formation of ≈40% of the unresolved flux is inferred, on average. We suggest that uncontaminated mid-IR continuum imaging of AGN is an accurate proxy for their intrinsic power.

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“…A few studies, such as Rodriguez Espinosa, Rudy, & Jones (1987), Dultzin-Hacyan, Moles, & Masegosa (1988), Heckman et al (1989), González-Delgado & Pérez (1993), Colina et al (1997), González Delgado et al (1998), andOliva et al (1999), have found links between the Seyfert activity and star formation activity, although most suggest that the enhancement in star formation is seen only in Seyfert 2 galaxies. Since the ISO atlas has superior spatial resolution at mid-infrared wavelengths compared with most other previous infrared studies of the Seyfert-starburst connection, we should be able to examine whether enhanced star formation activity is found in Seyfert galaxies.…”

Section: Introductionmentioning

confidence: 99%

Star Formation in the [ITAL]Infrared Space Observatory[/ITAL] Atlas of Bright Spiral Galaxies

Bendo¹,

Joseph²,

Wells³

et al. 2002

The Astronomical Journal

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We investigate star formation along the Hubble sequence using the Infrared Space Observatory Atlas of Bright Spiral Galaxies. Using mid-infrared and far-infrared flux densities normalized by K-band flux densities as indicators of recent star formation, we find several trends. First, star formation activity is stronger in late-type (Sc-Scd) spirals than in early-type (Sa-Sab) spirals. This trend is seen both in nuclear and disk activity. These results confirm several previous optical studies of star formation along the Hubble sequence but conflict with the conclusions of most of the previous studies using IRAS data, and we discuss why this might be so. Second, star formation is significantly more extended in later type spirals than in early-type spirals. We suggest that these trends in star formation are a result of differences in the gas content and its distribution along the Hubble sequence, and it is these differences that promote star formation in late-type spiral galaxies. We also search for trends in nuclear star formation related to the presence of a bar or nuclear activity. The nuclear star formation activity is not significantly different between barred and unbarred galaxies. We do find that star formation activity appears to be inhibited in low ionization nuclear emission regions and transition objects compared with H ii galaxies. The mean star formation rate in the sample is 1.4 M yr À1 , based on global far-infrared fluxes. Combining these data with CO data gives a mean gas consumption time of 6.4 Â 10 8 yr, which is $5 times lower than the values found in other studies. Finally, we find excellent support for the Schmidt law in the correlation between molecular gas masses and recent star formation in this sample of spiral galaxies.

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Star formation in Seyfert galaxies

Cited by 62 publications

References 4 publications

N‐Band Imaging of Seyfert Nuclei and the Mid‐Infrared–X‐Ray Correlation

N‐Band Imaging of Seyfert Nuclei and the Mid‐Infrared–X‐Ray Correlation

Resolving the mid-infrared cores of local Seyferts

Star Formation in the [ITAL]Infrared Space Observatory[/ITAL] Atlas of Bright Spiral Galaxies

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