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arXiv · 2308.12993

The MUSE Ultra Deep Field (MUDF). IV. A pair of X-ray weak quasars at the heart of two extended Ly{\alpha} nebulae

Elisabeta Lusso·Emanuele Nardini·Michele Fumagalli·Matteo Fossati·Fabrizio Arrigoni Battaia·Mitchell Revalski·Marc Rafelski·Valentina D'Odorico·Celine Peroux·Stefano Cristiani·Pratika Dayal·Francesco Haardt·Emma K. Lofthouse
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Abstract

We present the results obtained from follow-up observations of the MUSE Ultra Deep Field (MUDF) at X-ray energies with XMM-Newton. The MUDF is centred on a unique field with two bright, physically associated quasars at $z\simeq3.23$, separated by $\sim$500 kpc in projection. Both quasars are embedded within extended Ly$\alpha$ nebulae ($\gtrsim 100~\rm kpc$ at a surface brightness flux level of $\approx 6\times 10^{-19} \rm erg~s^{-1}~cm^{-2}~arcsec^{-2}$), whose elongated morphology is suggestive of an extended filament connecting the quasar haloes. The new X-ray observations presented here allow us to characterise the physical properties (e.g. X-ray slope, luminosities, gas column densities) in the innermost region of the MUDF quasars. We find that both quasars are X-ray underluminous compared to objects at similar ultraviolet luminosities. Based on our X-ray spectral analysis, absorbing columns of $N_H(z)\gtrsim$ 10$^{23}$ cm$^{-2}$ appear unlikely, therefore such a weakness is possibly intrinsic. When also including literature data, we do not observe any detectable trend between the area of the nebulae and nuclear luminosities at both the rest-frame 2 keV and 2500 $\rm \mathring{A}$. The area is also not correlated with the X-ray photon index nor with the integrated band flux in the hard band (2$-$10 keV). We also do not find any trend between the extended Ly$\alpha$ emission of the nebulae and the nuclear X-ray luminosity. Finally, the properties of the MUDF quasars' nebulae are consistent with the observed relation between the Ly$\alpha$ integrated luminosity of the nebulae and their area. Our results suggest that the quasar ionization power is not a strong driver of the morphology and size of the nebulae.

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Elisabeta Lusso, Emanuele Nardini, Michele Fumagalli, Matteo Fossati, Fabrizio Arrigoni Battaia, Mitchell Revalski, Marc Rafelski, Valentina D'Odorico, Celine Peroux, Stefano Cristiani, Pratika Dayal, Francesco Haardt, Emma K. Lofthouse. 2023-08-24. The MUSE Ultra Deep Field (MUDF). IV. A pair of X-ray weak quasars at the heart of two extended Ly{\alpha} nebulae. https://arxiv.org/abs/2308.12993

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