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Herschel-ATLAS/GAMA : a difference between star formation rates in strong-line and weak-line radio galaxies

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Abstract
We have constructed a sample of radio-loud objects with optical spectroscopy from the Galaxy and Mass Assembly (GAMA) project over the Herschel Astrophysical Terahertz Large Area Survey (Herschel-ATLAS) Phase 1 fields. Classifying the radio sources in terms of their optical spectra, we find that strong-emission-line sources ('high-excitation radio galaxies') have, on average, a factor of similar to 4 higher 250-mu m Herschel luminosity than weak-line ('low-excitation') radio galaxies and are also more luminous than magnitude-matched radio-quiet galaxies at the same redshift. Using all five H-ATLAS bands, we show that this difference in luminosity between the emission-line classes arises mostly from a difference in the average dust temperature; strong-emission-line sources tend to have comparable dust masses to, but higher dust temperatures than, radio galaxies with weak emission lines. We interpret this as showing that radio galaxies with strong nuclear emission lines are much more likely to be associated with star formation in their host galaxy, although there is certainly not a one-to-one relationship between star formation and strong-line active galactic nuclei (AGN) activity. The strong-line sources are estimated to have star formation rates at least a factor of 3-4 higher than those in the weak-line objects. Our conclusion is consistent with earlier work, generally carried out using much smaller samples, and reinforces the general picture of high-excitation radio galaxies as being located in lower-mass, less evolved host galaxies than their low-excitation counterparts.
Keywords
STARBURST-AGN CONNECTION, SCIENCE DEMONSTRATION PHASE, DIGITAL SKY SURVEY, LESS-THAN 0.5, LOUD AGN, HOST GALAXIES, PHYSICAL-PROPERTIES, INFRARED-EMISSION, ELLIPTIC GALAXIES, radio continuum: galaxies, infrared: galaxies, galaxies: active, ACTIVE GALACTIC NUCLEI

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Citation

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Chicago
Hardcastle, MJ, JHY Ching, JS Virdee, MJ Jarvis, SM Croom, EM Sadler, T Mauch, et al. 2013. “Herschel-ATLAS/GAMA : a Difference Between Star Formation Rates in Strong-line and Weak-line Radio Galaxies.” Monthly Notices of the Royal Astronomical Society 429 (3): 2407–2424.
APA
Hardcastle, M., Ching, J., Virdee, J., Jarvis, M., Croom, S., Sadler, E., Mauch, T., et al. (2013). Herschel-ATLAS/GAMA : a difference between star formation rates in strong-line and weak-line radio galaxies. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 429(3), 2407–2424.
Vancouver
1.
Hardcastle M, Ching J, Virdee J, Jarvis M, Croom S, Sadler E, et al. Herschel-ATLAS/GAMA : a difference between star formation rates in strong-line and weak-line radio galaxies. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY. 2013;429(3):2407–24.
MLA
Hardcastle, MJ, JHY Ching, JS Virdee, et al. “Herschel-ATLAS/GAMA : a Difference Between Star Formation Rates in Strong-line and Weak-line Radio Galaxies.” MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 429.3 (2013): 2407–2424. Print.
@article{4385786,
  abstract     = {We have constructed a sample of radio-loud objects with optical spectroscopy from the Galaxy and Mass Assembly (GAMA) project over the Herschel Astrophysical Terahertz Large Area Survey (Herschel-ATLAS) Phase 1 fields. Classifying the radio sources in terms of their optical spectra, we find that strong-emission-line sources ('high-excitation radio galaxies') have, on average, a factor of similar to 4 higher 250-mu m Herschel luminosity than weak-line ('low-excitation') radio galaxies and are also more luminous than magnitude-matched radio-quiet galaxies at the same redshift. Using all five H-ATLAS bands, we show that this difference in luminosity between the emission-line classes arises mostly from a difference in the average dust temperature; strong-emission-line sources tend to have comparable dust masses to, but higher dust temperatures than, radio galaxies with weak emission lines. We interpret this as showing that radio galaxies with strong nuclear emission lines are much more likely to be associated with star formation in their host galaxy, although there is certainly not a one-to-one relationship between star formation and strong-line active galactic nuclei (AGN) activity. The strong-line sources are estimated to have star formation rates at least a factor of 3-4 higher than those in the weak-line objects. Our conclusion is consistent with earlier work, generally carried out using much smaller samples, and reinforces the general picture of high-excitation radio galaxies as being located in lower-mass, less evolved host galaxies than their low-excitation counterparts.},
  author       = {Hardcastle, MJ and Ching, JHY and Virdee, JS and Jarvis, MJ and Croom, SM and Sadler, EM and Mauch, T and Smith, DJB and Stevens, JA and Baes, Maarten and Baldry, IK and Brough, S and Cooray, A and Dariush, A and De Zotti, G and Driver, S and Dunne, L and Dye, S and Eales, S and Hopwood, R and Liske, J and Maddox, S and Michalowski, Michal and Rigby, EE and Robotham, ASG and Steele, O and Thomas, D and Valiante, E},
  issn         = {0035-8711},
  journal      = {MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY},
  keyword      = {STARBURST-AGN CONNECTION,SCIENCE DEMONSTRATION PHASE,DIGITAL SKY SURVEY,LESS-THAN 0.5,LOUD AGN,HOST GALAXIES,PHYSICAL-PROPERTIES,INFRARED-EMISSION,ELLIPTIC GALAXIES,radio continuum: galaxies,infrared: galaxies,galaxies: active,ACTIVE GALACTIC NUCLEI},
  language     = {eng},
  number       = {3},
  pages        = {2407--2424},
  title        = {Herschel-ATLAS/GAMA : a difference between star formation rates in strong-line and weak-line radio galaxies},
  url          = {http://dx.doi.org/10.1093/mnras/sts510},
  volume       = {429},
  year         = {2013},
}

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