%0 Generic %1 Bouche2011 %A Bouche, N. %A Murphy, M. T. %A Peroux, C. %A Contini, T. %A Martin, C. L. %A Schreiber, N. M. Forster %A Genzel, R. %A Lutz, D. %A Gillessen, S. %A Tacconi, L. %A Davies, R. %A Eisenhauer, F. %D 2011 %K als detection dla ha high-z %T Enriched halos at redshift $z=2$ with no star-formation: Implications for accretion and wind scenarios %U http://arxiv.org/abs/1107.4618 %X Abridged In order to understand which process (e.g. galactic winds, cold accretion) is responsible for the cool (T~10^4 K) halo gas around galaxies, we embarked on a program to study the star-formation properties of galaxies selected by their MgII absorption signature in quasar spectra. Specifically, we searched for the H-alpha line emission from galaxies near very strong z=2 MgII absorbers (with rest-frame equivalent width EW>2 \AA) because these could be the sign-posts of outflows or inflows. Surprisingly, we detect H-alpha from only 4 hosts out of 20 sight-lines (and 2 out of the 19 HI-selected sight-lines), despite reaching a star-formation rate (SFR) sensitivity limit of 2.9 M/yr (5-sigma) for a Chabrier initial mass function. This low success rate is in contrast with our z=1 survey where we detected 66%\ (14/21) of the MgII hosts. Taking into account the difference in sensitivity between the two surveys, we should have been able to detect >11.4 of the 20 z=2 hosts whereas we found only 4 galaxies. Interestingly, all the z=2 detected hosts have observed SFR greater than 9 M/yr, well above our sensitivity limit, while at z=1 they all have SFR less than 9 M/yr, an evolution that is in good agreement with the evolution of the SFR main sequence. Moreover, we show that the z=2 undetected hosts are not hidden under the quasar continuum after stacking our data and that they also cannot be outside our surveyed area. Hence, strong MgII absorbers could trace star-formation driven winds in low-mass halos (Mhalo < 10^10.6 Msun). Alternatively, our results imply that z=2 galaxies traced by strong MgII absorbers do not form stars at a rate expected (3--10 M/yr) for their (halo or stellar) masses, supporting the existence of a transition in accretion efficiency at Mhalo ~ 10^11 Msun. This scenario can explain both the detections and the non-detections.

@misc{Bouche2011, abstract = { [Abridged] In order to understand which process (e.g. galactic winds, cold accretion) is responsible for the cool (T~10^4 K) halo gas around galaxies, we embarked on a program to study the star-formation properties of galaxies selected by their MgII absorption signature in quasar spectra. Specifically, we searched for the H-alpha line emission from galaxies near very strong z=2 MgII absorbers (with rest-frame equivalent width EW>2 \AA) because these could be the sign-posts of outflows or inflows. Surprisingly, we detect H-alpha from only 4 hosts out of 20 sight-lines (and 2 out of the 19 HI-selected sight-lines), despite reaching a star-formation rate (SFR) sensitivity limit of 2.9 M/yr (5-sigma) for a Chabrier initial mass function. This low success rate is in contrast with our z=1 survey where we detected 66%\ (14/21) of the MgII hosts. Taking into account the difference in sensitivity between the two surveys, we should have been able to detect >11.4 of the 20 z=2 hosts whereas we found only 4 galaxies. Interestingly, all the z=2 detected hosts have observed SFR greater than 9 M/yr, well above our sensitivity limit, while at z=1 they all have SFR less than 9 M/yr, an evolution that is in good agreement with the evolution of the SFR main sequence. Moreover, we show that the z=2 undetected hosts are not hidden under the quasar continuum after stacking our data and that they also cannot be outside our surveyed area. Hence, strong MgII absorbers could trace star-formation driven winds in low-mass halos (Mhalo < 10^{10.6} Msun). Alternatively, our results imply that z=2 galaxies traced by strong MgII absorbers do not form stars at a rate expected (3--10 M/yr) for their (halo or stellar) masses, supporting the existence of a transition in accretion efficiency at Mhalo ~ 10^{11} Msun. This scenario can explain both the detections and the non-detections. }, added-at = {2011-07-26T19:04:42.000+0200}, author = {Bouche, N. and Murphy, M. T. and Peroux, C. and Contini, T. and Martin, C. L. and Schreiber, N. M. Forster and Genzel, R. and Lutz, D. and Gillessen, S. and Tacconi, L. and Davies, R. and Eisenhauer, F.}, biburl = {https://www.bibsonomy.org/bibtex/2a7d87254911a4e21326e5d3db58a95ff/miki}, description = {[1107.4618] Enriched halos at redshift $z=2$ with no star-formation: Implications for accretion and wind scenarios}, interhash = {4b4bc1b90807baa1824c4ba0b517cd0c}, intrahash = {a7d87254911a4e21326e5d3db58a95ff}, keywords = {als detection dla ha high-z}, note = {cite arxiv:1107.4618 Comment: accepted for publication in MNRAS}, timestamp = {2011-07-26T19:04:42.000+0200}, title = {Enriched halos at redshift $z=2$ with no star-formation: Implications for accretion and wind scenarios}, url = {http://arxiv.org/abs/1107.4618}, year = 2011 }