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Understanding how galaxies quench their star formation is crucial for studies of galaxy evolution. Quenching is related to a decrease of cold gas. In the first paper we showed that the dust removal timescale in early-type galaxies (ETGs) is about 2.5 Gyr. Here we present carbon monoxide and 21 cm hydrogen line observations of these galaxies and measure the timescale of removal of the cold interstellar medium (ISM). We find that all the cold ISM components (dust and molecular and atomic gas) decline at similar rates. This allows us to rule out a wide range of potential ISM-removal mechanisms (including starburst-driven outflows, astration, or a decline in the number of asymptotic giant branch stars), and artificial effects like the stellar mass–age correlation, environmental influence, mergers, and selection bias, leaving ionization by evolved low-mass stars and ionization/outflows by Type Ia supernovae or active galactic nuclei as viable mechanisms. We also provide evidence for an internal origin of the detected ISMs. Moreover, we find that the quenching of star formation in these galaxies cannot be explained by a reduction in the gas amount alone, because the star formation rates (SFRs) decrease faster (on a timescale of about 1.8 Gyr) than the amount of cold gas. Furthermore, the star formation efficiency (SFE) of the ETGs (SFE SFR MH2 º ) is lower than that of star-forming galaxies, whereas their gas mass fractions ( fH MH M 2 º 2 *) are normal. This may be explained by the stabilization of gas against fragmentation, for example due to morphological quenching, turbulence, or magnetic fields.

An unambiguous manifestation of the magnification bias is the cross-correlation between two source samples with non-overlapping redshift distributions. In this work we measure and study the cross-correlation signal between a foreground sample of GAMA galaxies with spectroscopic redshifts in the range 0:2 < z < 0:8, and a background sample of HATLAS galaxies with photometric redshifts & 1:2. It constitutes a substantial improvement over the cross-correlation measurements made by Gonzalez-Nuevo et al. (2014) with updated catalogues and wider area (with S=N & 5 below 10 arcmin and reaching S=N _ 20 below 30 arcsec). The better statistics allow us to split the sample in different redshift bins and to perform a tomographic analysis (with S=N & 3 below 10 arcmin and reaching S=N _ 15 below 30 arcsec). Moreover, we implement a halo model to extract astrophysical information about the background galaxies and the detectors that are producing the lensing link between the foreground (lenses) and background (sources) samples. In the case of the sources, we find typical mass values in agreement with previous studies: a minimum halo mass to host a central galaxy, Mmin _ 1012:26M_, and a pivot halo mass to have at least one sub-halo satellite, M1 _ 1012:84M_. However, the lenses are massive galaxies or even galaxy groups/clusters, with minimum mass of Mlens min _ 1013:06M_. Above a mass of Mlens 1 _ 1014:57M_ they contain at least one additional satellite galaxy which contributes to the lensing effect. The tomographic analysis shows that, while Mlens 1 is almost redshift independent, there is a clear evolution of increase Mlens min with redshift in agreement with theoretical estimations. Finally, the halo modeling allows us to identify a strong lensing contribution to the cross-correlation for angular scales below 30 arcsec. This interpretation is supported by the results of basic but effective simulations.

An unambiguous manifestation of the magnification bias is the cross-correlation between two source samples with non-overlapping redshift distributions. In this work we measure and study the cross-correlation signal between a foreground sample of GAMA galaxies with spectroscopic redshifts in the range 0:2 < z < 0:8, and a background sample of HATLAS galaxies with photometric redshifts & 1:2. It constitutes a substantial improvement over the cross-correlation measurements made by Gonzalez-Nuevo et al. (2014) with updated catalogues and wider area (with S=N & 5 below 10 arcmin and reaching S=N _ 20 below 30 arcsec). The better statistics allow us to split the sample in different redshift bins and to perform a tomographic analysis (with S=N & 3 below 10 arcmin and reaching S=N _ 15 below 30 arcsec). Moreover, we implement a halo model to extract astrophysical information about the background galaxies and the detectors that are producing the lensing link between the foreground (lenses) and background (sources) samples. In the case of the sources, we find typical mass values in agreement with previous studies: a minimum halo mass to host a central galaxy, Mmin _ 1012:26M_, and a pivot halo mass to have at least one sub-halo satellite, M1 _ 1012:84M_. However, the lenses are massive galaxies or even galaxy groups/clusters, with minimum mass of Mlens min _ 1013:06M_. Above a mass of Mlens 1 _ 1014:57M_ they contain at least one additional satellite galaxy which contributes to the lensing effect. The tomographic analysis shows that, while Mlens 1 is almost redshift independent, there is a clear evolution of increase Mlens min with redshift in agreement with theoretical estimations. Finally, the halo modeling allows us to identify a strong lensing contribution to the cross-correlation for angular scales below 30 arcsec. This interpretation is supported by the results of basic but effective simulations.

An unambiguous manifestation of the magnification bias is the cross-correlation between two source samples with non-overlapping redshift distributions. In this work we measure and study the cross-correlation signal between a foreground sample of GAMA galaxies with spectroscopic redshifts in the range 0:2 < z < 0:8, and a background sample of HATLAS galaxies with photometric redshifts & 1:2. It constitutes a substantial improvement over the cross-correlation measurements made by Gonzalez-Nuevo et al. (2014) with updated catalogues and wider area (with S=N & 5 below 10 arcmin and reaching S=N _ 20 below 30 arcsec). The better statistics allow us to split the sample in different redshift bins and to perform a tomographic analysis (with S=N & 3 below 10 arcmin and reaching S=N _ 15 below 30 arcsec). Moreover, we implement a halo model to extract astrophysical information about the background galaxies and the detectors that are producing the lensing link between the foreground (lenses) and background (sources) samples. In the case of the sources, we find typical mass values in agreement with previous studies: a minimum halo mass to host a central galaxy, Mmin _ 1012:26M_, and a pivot halo mass to have at least one sub-halo satellite, M1 _ 1012:84M_. However, the lenses are massive galaxies or even galaxy groups/clusters, with minimum mass of Mlens min _ 1013:06M_. Above a mass of Mlens 1 _ 1014:57M_ they contain at least one additional satellite galaxy which contributes to the lensing effect. The tomographic analysis shows that, while Mlens 1 is almost redshift independent, there is a clear evolution of increase Mlens min with redshift in agreement with theoretical estimations. Finally, the halo modeling allows us to identify a strong lensing contribution to the cross-correlation for angular scales below 30 arcsec. This interpretation is supported by the results of basic but effective simulations.

An unambiguous manifestation of the magnification bias is the cross-correlation between two source samples with non-overlapping redshift distributions. In this work we measure and study the cross-correlation signal between a foreground sample of GAMA galaxies with spectroscopic redshifts in the range 0:2 < z < 0:8, and a background sample of HATLAS galaxies with photometric redshifts & 1:2. It constitutes a substantial improvement over the cross-correlation measurements made by Gonzalez-Nuevo et al. (2014) with updated catalogues and wider area (with S=N & 5 below 10 arcmin and reaching S=N _ 20 below 30 arcsec). The better statistics allow us to split the sample in different redshift bins and to perform a tomographic analysis (with S=N & 3 below 10 arcmin and reaching S=N _ 15 below 30 arcsec). Moreover, we implement a halo model to extract astrophysical information about the background galaxies and the detectors that are producing the lensing link between the foreground (lenses) and background (sources) samples. In the case of the sources, we find typical mass values in agreement with previous studies: a minimum halo mass to host a central galaxy, Mmin _ 1012:26M_, and a pivot halo mass to have at least one sub-halo satellite, M1 _ 1012:84M_. However, the lenses are massive galaxies or even galaxy groups/clusters, with minimum mass of Mlens min _ 1013:06M_. Above a mass of Mlens 1 _ 1014:57M_ they contain at least one additional satellite galaxy which contributes to the lensing effect. The tomographic analysis shows that, while Mlens 1 is almost redshift independent, there is a clear evolution of increase Mlens min with redshift in agreement with theoretical estimations. Finally, the halo modeling allows us to identify a strong lensing contribution to the cross-correlation for angular scales below 30 arcsec. This interpretation is supported by the results of basic but effective simulations.