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Infrared data

Radio data

Optical data

X-Ray data

Spitzer 70um DataPKS0409-75_files/0409_70um.fits
Spitzer 160um DataPKS0409-75_files/0409_160um.fits
ATCA 5GHzPKS0409-75_files/
ESO Optical spectraPKS0409-75_files/

Spitzer IRS spectra


(Top) Image of 0409-75 at 3-cm (full resolution) with superimposed vectors indicating the projected electric field direction. The vectors are proportional in length to the fractional polarisation (1 arcsec = 0.22 ratio). The contour levels are: , 1, 2, 4, 8, 16, 32, 64, 128, 256 mJy beam-1. The peak flux is 1.255 Jy beam-1. The cross indicates the position (from di Serego et al. 1994) of the optical galaxy. (Bottom) Image of 0409-75 at 6-cm with superimposed vectors indicating the projected electric field direction. The vectors are proportional in length to the fractional polarisation (1 arcsec = 0.15 ratio). The contour levels are: , 1, 2, 4, 8, 16, 32, 64, 128, 256 mJy beam-1. The peak flux is 2.349 Jy beam-1

Morganti et al. (1999)


Optical spectrum taken with ESO telescopes.

Tadhunter et al. (1993)

Spitzer 24um DataPKS0409-75_files/0409_24um.fits


Spitzer MIPS infrared photometric observations. Left to right: 24 microns, 70 microns and 160 microns (when available). FOV are 5x5 arcmins for 24 microns, 5x2.5 arcmins for 70 microns and 0.5x5 arcmins for 160 microns.

Dicken et al. (2008)

Next objectPKS0427-53.html
Frequency       Flux      Units	                Reference                
5GHz	         4.25	      Jy                       Morganti et al. (1993)
[OIII] λ5007     -13.99      Log erg/cm2/s    Tadhunter et al. (1993) 15GHz core       <10         mJy        	        Dicken et al. (2008)
22 GHz core      <9           mJy	                 Dicken et al. (2008)
24 microns	 1.5	       mJy	                 Dicken et al. (2008)
70 microns	11.2         mJy	                 Dicken et al. (2008)
160 microns	<36.4       mJy	                 Dicken et al. (2008)
X-ray            	-	        -	                 -

Other name:


RA (j2000):

Dec (j2000):

Optical class:

Radio Class:


04 08 48.49

-75 07 19.3




Gemini imagePKS0409-75_files/p0409.fits


    A NLRG/FRII at z = 0.693, PKS 0409−75 is both the most distant radio source in the 2Jy sample and the most powerful at radio wavelengths. Indeed, it is one of the most powerful intermediate-redshift radio sources in the southern hemisphere (S4.8 GHz = Log 28.17 W/Hz ; Morganti et al. 1993). The FR II radio source is relatively small (largest angular size, LAS = 9 arcsec or 85 kpc) and is dominated by two lobes of emission extending along PA130 (Morganti et al. 1999). PKS 0409−75 is optically identified with a m_V = 21.6 galaxy which is resolved into two components and displays extended emission in [OII]λ3727 (di Serego Alighieri et al. 1994).

    The low-resolution optical spectrum of PKS 0409−75 reveals a significant UV excess compared with passively evolving elliptical galaxies at similar redshifts (Tadhunter et al. 2002, Holt et al. 2007). The narrow emission-line luminosity and ionization state are relatively low for the radio power – in the optical spectrum the [OII]λ3727, [NeV]λ3426, [NeIII]λ3869, H and [OIII]λ5007 emission lines have been detected, however, the [O III] is barely detected whilst [O II] is relatively strong in the spectrum presented by Tadhunter et al. (1993). Tadhunter et al. (2002) attempted to model the optical/UV continuum but were unable to obtain a result due to poor sky subtraction. They do report a measurement of the 4000 Å break which suggests 95% of the light in the 3750–3950 Å region is not emitted by the old stellar population.

    Spectral synthesis modelling of a deep VLT optical spectrum of the integrated light of the host galaxy by Holt et al. (2007) demonstrates that a contribution from a stellar component of relatively young (<0.05 Gyr) age is required to model its SED accurately.  Our GMOS-S i′-band image reveals a secondary nucleus of similar brightness to the radio galaxy ∼8 kpc to the east along PA = 84 degrees. Note that the axis of the double nucleus is misaligned by ∼40◦ from the axis of the large-scale radio structure (PA = 124 degrees). The double nucleus system lies in a crowded field, and there are a number of galaxies of similar brightness within 150 kpc. Although the system looks disturbed, unfortunately the high value of the seeing measured for this image (FWHM = 1.15 arcsec) prevents any more detailed morphological classification. The continuum or line-emitting nature of the secondary nucleus is uncertain based on long-slit spectra of this source.

    Further evidence for recent star formation activity is provided by Spitzer observations which demonstrate that it has a high 70-μm luminosity for its (relatively modest) emission-line luminosity (Dicken et al. 2009), as well as cool MFIR colours. However, there is a possibility that the non-thermal synchrotron radio lobe emission may contaminate the MFIR flux in this radio galaxy, because the lobes lie within the Spitzer beam (Dicken et al. 2008).


Gemini GMOS-S Unsharp masked image

Ramos Almeida et al. (2011a)

Gemini/GMOS-S: median filtered image

    3 cm ATCA radio map



Spectral energy distribution.  The blue solid line is fitted to the data from 109 to 1010 Hz. Extrapolating this line from the radio to the infrared SED tests whether non-thermal synchrotron emission from the lobes can contaminate the Spitzer mid-infrared flux. In this case the lobes emission lies inside the Spitzer beam so non-thermal contamination is a possibility for the Spitzer data. However, the weak, flat spectrum, non-thermal radio core emission is not likely to contaminate the Spitzer infrared flux data for this object.

Dicken et al. (2008)


Spitzer IRS spectra

Dicken et al. (in preperation)