QSOs acting as gravitational lenses: halo mass and projected mass density profile at $zsim0.7$. (arXiv:1902.03624v1 [astro-ph.CO])

QSOs acting as gravitational lenses: halo mass and projected mass density profile at $zsim0.7$. (arXiv:1902.03624v1 [astro-ph.CO])
<a href="http://arxiv.org/find/astro-ph/1/au:+Bonavera_L/0/1/0/all/0/1">L. Bonavera</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gonzalez_Nuevo_J/0/1/0/all/0/1">J. Gonz&#xe1;lez-Nuevo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gomez_S/0/1/0/all/0/1">S.L. Su&#xe1;rez G&#xf3;mez</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lapi_A/0/1/0/all/0/1">A. Lapi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bianchini_F/0/1/0/all/0/1">F. Bianchini</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Negrello_M/0/1/0/all/0/1">M. Negrello</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Alonso_E/0/1/0/all/0/1">E. D&#xed;ez Alonso</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Santos_J/0/1/0/all/0/1">J. D. Santos</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Juez_F/0/1/0/all/0/1">F. J. de Cos Juez</a>

Magnification bias is a gravitational lensing effect that is normally
overlooked because it is considered sub-optimal in comparison with the lensing
shear. Thanks to the demonstrated optimal characteristics of the sub-millimetre
galaxies (SMGs) for lensing analysis, in this work we were able to measure the
magnification bias produced by a sample of QSOs acting as lenses, $0.2 13.6_{-0.4}^{+0.9}$, also
confirmed by the mass density profile analysis
($M_{NFW}=1.6_{-0.5}^{+2.1}times10^{14} M_odot$). These mass values indicate
that we are observing the lensing effect of a cluster size halo signposted by
the QSOs. Moreover, we were able to estimate the lensing convergence,
$kappa(theta)$, for our magnification bias measurements down to a few kpcs.
The derived mass density profile shows a core in its centre and it is
compatible with a Navarro-Frank-White (NFW) profile. The core radius,
$r_c=30_{-10}^{+14}$ kpc, was estimated using a cored Singular Isothermal
Sphere profile that fits even better the data. In addition, we were not able to
detect any baryonic/stellar component at very small scales. Both results could
indicate the effect of a strong baryonic feedback produced by the active
galactic nuclei in the centre of the QSOs responsible of the removal of the
expected cusp.

Magnification bias is a gravitational lensing effect that is normally
overlooked because it is considered sub-optimal in comparison with the lensing
shear. Thanks to the demonstrated optimal characteristics of the sub-millimetre
galaxies (SMGs) for lensing analysis, in this work we were able to measure the
magnification bias produced by a sample of QSOs acting as lenses, $0.2<z<1.0$,
on the SMGs observed by Herschel at $1.2<z<4.0$. Two different methodologies
were successfully applied: the traditional cross-correlation function approach
and the stacking technique. The second one was found to be more robust for
analysing the strong lensing regime ($<20-30$ arcsec in our case) and provides,
in addition, a density map of the lensing effect. From the halo modelling of
the cross-correlation function, the QSOs host halo mass was estimated to be
greater than $log_{10}{(M_{min}/M_odot)} > 13.6_{-0.4}^{+0.9}$, also
confirmed by the mass density profile analysis
($M_{NFW}=1.6_{-0.5}^{+2.1}times10^{14} M_odot$). These mass values indicate
that we are observing the lensing effect of a cluster size halo signposted by
the QSOs. Moreover, we were able to estimate the lensing convergence,
$kappa(theta)$, for our magnification bias measurements down to a few kpcs.
The derived mass density profile shows a core in its centre and it is
compatible with a Navarro-Frank-White (NFW) profile. The core radius,
$r_c=30_{-10}^{+14}$ kpc, was estimated using a cored Singular Isothermal
Sphere profile that fits even better the data. In addition, we were not able to
detect any baryonic/stellar component at very small scales. Both results could
indicate the effect of a strong baryonic feedback produced by the active
galactic nuclei in the centre of the QSOs responsible of the removal of the
expected cusp.

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