DIFA(UNIBO) – Project 1 · DIFA(UNIBO) – Project 1 “The effect of AGN feedback on the gas consumption in high-redshift galaxies” Supervisor: Marcella Brusa ([email protected])

DIFA(UNIBO) – Project 1

“The effect of AGN feedback on the gas consumption in high-redshift galaxies”

Supervisor: Marcella Brusa ([email protected])

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PhD project in ASTROPHYSICS

Title of the Project: The effect of AGN feedback on the gas consumption in high-redshift galaxiesSupervisor: Dr. Marcella Brusa (DIFA)In collaboration with: Margherita Talia, Francesca Pozzi

Scientific Case: In recent years, observations of cold molecular gas reservoirs at high redshift (z>1) have been crucial in studying the rate at which gas is converted into stars in “normal” galaxies and in quasar systems. In particular, Spectral Line Energy Distributions (SLEDs) and excitation modeling studies of CO line fluxes up to mid-/high-J transitions of high- z unobscured QSO hosts have suggested that the molecular gas is in a higher excitation state than that observed in SMGs, in agreement with the picture that unobscured quasars represent a subsequent stage in the early evolution of massive galaxies (e.g. Hopkins et al. 2008). The fact that high Star Formation Efficiencies (SFEs) are also observed in these systems where the Star Formation Rate (SFR) is expected to have been already substantially diminished, seems to be instead in contradiction with models’ predictions. A possible explanation may be that, instead of higher efficiency in converting gas into stars, the high SFE observed in very luminous QSOs is a result of a low molecular gas content with respect to their current SFR, as indeed expected if most of the gas has been already consumpted.

Molecular gas studies at z>1 have been extended only recently to other classes of AGN systems including reddened ones and/or QSOs with pre-existing evidences of outflow signatures in the ionised gas component extending over the entire host galaxy (e.g. Brusa et al. 2015). In several cases, the millimeter observations returnedlow depletion time scales (see e.g the coloured points at sSFR/sSFR_MS <~1 in the figure, to be compared with the grey points and solid lines which mark the trends expected for “normal” galaxies), suggesting that the available samples used to predict the CO luminosities (unobscured QSOs, mostly associated with ULIRGs systems) were not representative of the molecular gas content of the full AGN population.

So far the results are based on the study of few sources. With this project, we aim at performing a systematic study of the gas content and gas consumption of a large sample (~hundreds) of high-z AGN (z=1-4), selected spanning a large range of luminosities and accretion properties. The project will rely on the exploitation of the large ALMA archive and their match with X-ray selected AGN and optical/NIR spectroscopic data, with the possibility to follow-up interesting/peculiar sources at other wavelengths.

Outline of the Project: During the PhD project, the candidate will have the opportunity: to design and optimise the sample selection by matching ALMA data archive and known X-ray AGN samples from large area (eg/ COSMOS, XLL) and pencil beam (e.g. CDFS) surveys; perform ALMA data analysis to characterize the flux and spectral properties of the samples sources and fully exploit the 3D datacube; employ 1D, 2D and 3D fitting tools to constrain the kinematics properties of the sources with particular emphasis on the search for molecular outflows; model the gas excitation through the use of state-of-the-art photo-ionization codes; compare with theoretical model predictions.Contacts: [email protected]

mailto:[email protected]


“ X-ray observations of galaxy-wide outflows: the origin of super winds”

Supervisor: Marcella Brusa ([email protected])

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PhD project in ASTROPHYSICS

Title of the Project: X-ray observations of galaxy-wide outflows: the origin of super winds

Supervisor: Dr. Marcella Brusa (DIFA), Co-supervisors: Dr. Giorgio Lanzuisi (DIFA)

Scientific Case: We know that almost all massive galaxies host a Supermassive Black Hole (SMBH, M=106 -109 solar masses) at their very center and that the mass of these dark objects well correlates with the properties of the host galaxies. This implies that some mechanisms had to link the small central regions, where the gravitational field of the SMBH dominates, to the larger scales where the influence of the central objects is expected to be negligible. According to the most recent models of Active Galactic Nuclei (AGN) and galaxies co-evolution, gas flows in the form of energet ic w inds (outflows) are believed to play a pivotal role in this process, given that they regulate both accretion and ejection of material onto and from compact objects and can propagate momentum and energy over a wide spatial scale.

Galactic-scale, massive winds are indeed observed, in the form of blue/red-shifted emission lines from ionized gas, in a large fraction of galaxies hosting an Active Galactic Nucleus (AGN). X-ray data are crucial in order to understand the link between outflow and accretion properties, such as mass accretion rate, amount of obscuration, presence of relativistic disk winds, etc.

With this project, we aim at performing the first systematic study of the X-ray emission from a large sample of “local” (z<0.8) AGN selected for having evidences of outflow/winds from their optical spectra. The project will rely on the exploitation of the large existing X-ray archives and their match with the optical spectroscopic data, mainly from the Sloan Digital Sky Survey, with the possibility to follow-up interesting/peculiar sources.

Outline of the Project: During the PhD project, the candidate will have the opportunity to perform data analysis from the most powerful X-ray telescopes currently operating (Chandra & XMM); characterize the spectral properties of a large sample of AGN, with particular emphasis on the search for highly obscured sources, model the relativistic disk winds through the use of state-of-the-art photo-ionization codes. The candidate will have the possibility to propose new observations with X-rays, Optical, sub-mm telescopes, to study the outflow properties (morphology) of interesting sources.

Contacts: [email protected]

mailto:[email protected]


“Massivegalaxiesascosmologicalprobes”

Supervisor: Andrea Cimatti ([email protected])

PhD project in ASTROPHYSICS Title of the Project: Massive galaxies as cosmological probes Supervisor: Andrea Cimatti Scientific Case Massive galaxies are fundamental evolutionary and cosmological probes. The age and metallicity properties of quiescent systems (e.g. ellipticals) suggest that most stellar mass was assembled at high redshifts during an intense and short phase of star formation. Massive star-forming galaxies have been identified spectroscopically at z~2-3, but it is not clear whether and which of these systems are the progenitors of massive ellipticals. Despite much less numerous than today, massive spheroidal galaxies were already present at z~2-3 and co-existed with the more abundant population of star-forming galaxies. It is surprizing that massive quiescent galaxy photometric candidates have been found up to very high redshifts (z~5). Should the nature of these systems be confirmed, this will open profound questions on the rapid assembly of massive galaxies in the ΛCDM cosmological framework. Current galaxy formation models do not fully reproduce the whole observed evolutionary pattern of massive galaxies. This suggests a complex evolutionary scenario that is not completely understood. Directly linked to the above questions is the light up of the first black holes (BHs) of the Universe and their growth as a function of cosmic time. Understanding the history of BH accretion and the effects of AGN feedback is essential to shed light on the co-evolution with galaxies and on the origin of the main scaling relations observed in the present-day Universe. Outline of the Projects The galaxies and cosmology groups at DIFA, in collaboration with INAF and the ALMA Regional Centre in Bologna, are fully involved in several projects and in the development of the Euclid mission. The available PhD projects make use of imaging and spectroscopic data from the deepest surveys available to date in the optical-infrared-millimeter (e.g. HST, VLT, Herschel, ALMA) in combination with multi-wavelength datasets from the X-rays to the radio. These projects will also pave the way to further studies in the context of the imminent NASA JWST and ESA Euclid space missions. Each PhD project will consist of four main steps: (1) analysis of the data, (2) estimate of physical and evolutionary parameters, (3) interpretation of the results, (4) comparison of the results with model predictions within ΛCDM cosmology. The topics of the projects are listed here below. The specific details will be discussed with the interested PhD students. (1) Searching for massive quiescent galaxies at very high redshifts. (2) The evolution of elliptical galaxies based on their stellar populations. (3) Estimating the expansion rate of the Universe with cosmic chronometers. (4) The evolution of gas and dust in high-redshift star-forming galaxies. (5) The influence of AGN feedback on galaxy formation and evolution. (6) The influence of the environment on galaxy formation and evolution. (7) Galaxy clustering as a cosmological probe. (8) High redshift galaxies with the Euclid space mission. Contacts: Andrea Cimatti ([email protected])


“EnlighteningtheGlobularCluster'sdarkside”

Supervisor: Francesco R. Ferraro ([email protected])

PhDprojectinASTROPHYSICSTitleoftheProject:EnlighteningtheGlobularCluster'sdarksideSupervisor:F.R.FerraroCo-supervisors:B.Lanzoni,A.Mucciarelli,C.PallancaScientific Case: TheUniversewe live in is dominated by darkness. Indeed, the vastmajorityofthematter(andpossiblyoftheenergy)intheUniverseisdark,whileonlyafew percent can be revealed through light signals. Fortunately the presence of darkmatter(DM)leavesimprintsinthekinematicalpropertiesofthevisiblemass,revealinginvisiblestructuresasDMhalosandsuper-massiveblackholes.Thisprojectisdevotedto study the kinematics of sub-galactic stellar systemswith the aim of unveiling andprobingtheexistenceofnon-visiblematterattheglobularcluster(GC)scales.Finding DM halos in sub-galactic structures would be crucial to alleviate thecosmological "missing satellite problem". Identifying intermediate-mass (103-105 M

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black holes (IMBHs) in GCs could shed new light on the formation processes of theSMBHsobservedingalaxiesandAGNsalreadyatredshiftz>6.PreciselydeterminingtheinternalstructureandkinematicsofGCswouldalso fillourcurrent lackofknowledgeaboutthephysicsofthesestellarsystems,whicharetrueastrophysicalmilestones.Outline of the Project: To address these issues we propose to perform the mostcomprehensivestudyeverattemptedtodeterminetheinternalstructureandkinematicsof GCs. Specifically, we propose to determine the projected density distribution, theVelocityDispersionprofileandtherotationcurve,fromtheverycenterouttothetidalradius and through unbiased methodologies, for a sample of 36 GGCs wellrepresentativeofdifferentstructuralparameters,dynamicalstagesandenvironmentalconditions.The line-of-sight (LOS) kinematics will be determined from the spectra of severalhundreds individual stars located along the entire extensionof eachGC, by exploitingstate-of-the-arttechnologyinanon-conventionalway.Weplantocombine:(i)AdaptiveOptics (AO) Integral Field Spectroscopy (IFS, mainly with SINFONI@VLT) in theinnermost cluster regions (arcsecond scale), (ii) seeing-limited IFS (mainly withKMOS@VLT)fortheintermediateradialrange(tensofarcsecondscale),and(iii)wide-field multi-object spectroscopy (mainly with FLAMES@VLT) for the most externalregions(fromonetotensarcminutescales). Thedataneededtoperformthispartoftheproject are already acquired by means of 2 Large Programmes at the ESO-VLT(proposals 193.D-0232 and 195.D-0750, PI: Ferraro, for a total of 300 hours ofobservingtime),complementedwithafewothercompanionprograms(morethan100additional hours) at the VLT (with XShooter and MUSE) and at Keck (with OSIRIS,NIRSPECandDEIMOS).PROPERMOTIONS -AccuratePMsof individual stars in the centerof eachGCwill becomputed frommulti-epochHST images.Thenoveltyofourapproach,withrespect tomostPMstudiesintheliterature,standsinthefactthatwewillfocusongiantstars,thesame forwhichLOSvelocitieswillbederived throughspectroscopy.Thiswillprovideus,forthefirsttime,withthe3Dkinematicsofdozensofcentralstars,thusallowingustoreconstructtheirorbitsandrecognizepossiblehigh-velocityobjectsacceleratedbyanIMBH. Moreover, we will properly sample the very central regions, where the most

interestingdynamicalprocessesareexpected tooccur (butwherePMsof starsbelowthe main sequence turnoff are not precisely measurable in most GCs because ofcrowding;seeWatkinsetal.2015,ApJ803,29).ThisiscrucialtodetectpossiblecentralLOSVelocityDispersioncusps.ThePMs(againforgiantstarsmainly)releasedinafewyears by theGAIA spacemissionwill complement this information, thusprovidinguswiththe3Dclusterkinematicsalongtheentireradialextension.Contacts:[email protected];[email protected];[email protected];[email protected]


“Gasflowsfromandtogalaxies”

Supervisor: Filippo Fraternali ([email protected])

PhDprojectinASTROPHYSICSTitleoftheProject:GasflowsfromandtogalaxiesSupervisor:FilippoFraternali,GabrielePezzulli(ETH,Zurigo,Svizzera)ScientificCase:Thespacearoundgalaxiesisfilledwithgasatverydifferenttemperatures:fromthehotvirialtemperature(T=10^6-10^7K)downtomuchlowertemperatures.Therelativeabundanceandphysicalstateofthisgasaresubjectsofactivecurrentinvestigationsastheyarethoughttoplaycrucialrolesintheevolutionofthehostgalaxies.Circumgalacticgascanhavedifferentorigins.Itcanbeoutflowingfromthegalaxiesandthusproducedbystellar/AGNfeedback,itcanbeinfallingfromtheIGMandcontributetothefeedingofthestarformationoritcanbeinhydrostaticequilibriuminthegalacticpotential.Ingeneral,thecircumgalacticmediumisexpectedtocontainalargefractionofbaryonicmaterialintheuniverseandsubstantiallycontributetothesolutionofthemissingbaryonproblem(e.g.Anderson&Bregman2010).Themoststrikingdiscoveryofthelastyearsisthepresenceofalargeamountofrelativelycoldmaterial(T~10^4K)inthecircumgalacticmediumofnearbyanddistantgalaxies(e.g.Werketal.2014).Thismaterialcannotbeinhydrostaticequilibriumgivenitslowtemperatureanditsdynamicalstateisunclear.Thus,newmodelsandtechniquesmustbedesignedtoinvestigatethephysicsandoriginofthisgascomponent.OutlineoftheProject:ThemaingoalofthisPhDprojectisthebuildingofaphysicalpicturetoexplainthepresenceofcoldmaterialinthecircumgalacticmediumofgalaxies.Thefirststepwillbetore-analyzetheobservationsofabsorptionlinesofWerketal.2014usingthephotoionizationmodelCLOUDYinordertoimprovethedeterminationofthecolumndensitiesofthematerial.Thisisnecessarybecauseinseverallinesofsighttherearemulticomponentabsorptionfeaturesthatmaycomefromverydifferentregionsofthecircumgalacticmediumduetoprojectioneffectsalongthelineofsight.Thesecondstepwillbetoconsiderequilibriummodelstreatingthecircumgalacticcloudsasacollision-lesssystem.ThestudentisexpectedtobuildJeansmodelsandexploredifferentrotationalpatternsinordertoinvestigatewhetherthedensitydistributionandthekinematicsobtainedfromthedataareconsistentwithequilibriumconfigurations.Finally,wewillconsiderinflowandoutflowmodels.Theinteractionbetweenthecoldcloudsandthehotvirial-temperaturegaswillbeexploredusinghigh-resolutionhydrodynamicalsimulations.Theinflowandoutflowpatternsresultingfromthesemodelswillbecomparedwiththedatatodeterminethepropertiesoftheflowanddisentanglebetweeninflowandoutflow.AttheendofthePhDproject,thestudentwillhaveadeepunderstandingofphysicsofmultiphasegasandanin-depthexpertiseindataanalysis,analyticalmodelingandhydrodynamicalsimulations.Contacts:[email protected],M.E,Bregman,J.N.2010,ApJ,714,320Werk,J.,Prochaska,J.X.,TumlinsonJ.etal.2014,ApJ,792,8


“DynamicsofgalaxiesacrosstheHubbletime””

Supervisor: Filippo Fraternali ([email protected])

PhDprojectinASTROPHYSICSTitleoftheProject:DynamicsofgalaxiesacrosstheHubbletimeSupervisor:FilippoFraternali,EnricoDiTeodoro(ANU,Canberra,Australia)ScientificCase:Coldgasingalaxies,eitherinmolecularoratomicform,typicallysettlesinrotatingdiscs.Thedeterminationoftherotationvelocityofthesediscs(rotationcurves),madepossibleviaemission-linedata,allowsustotracethegalacticpotentialandthedistributionofdarkmatterwithhighprecision.Thankstotheconstructionofnewfacilities,wearenowabletoperformthesemeasuresingalaxiesuptohighredshifts.TherotationvelocityalsoallowsustostudykeyscalingrelationsliketheTully-Fisherrelation,whoseevolutionwithredshiftgiveskeyinformationonthemassassembly.Asecondkeyquantitythatdescribesthedynamicalstateofthecoldgasingalaxiesisitsvelocitydispersion.Thisisameasureoftheturbulenceoftheinterstellarmediumanditisthoughttogovernnumerousevolutionaryphenomenasuchastheonsetofstarformation.Recentresultspointtoanincreaseofturbulenceingalaxiesathighredshiftpossiblyinrelationtotheformationofthestellarthickdiscs(e.g.Wisnioskietal.2015).Forallthesereasons,acoherentandprecisemeasureoftherotationvelocityandthevelocitydispersionofthecoldgasingalaxiesacrosstheHubbletimeisofcrucialimportancetounderstandhowgalaxiesgrewandformedstars.OutlineoftheProject:Thisprojectaimstoinvestigatethegasdynamicsingalaxiesatverydifferentuniversalepochsthroughtheaccuratederivationofthegasrotationanddispersionvelocities.Thefirststepoftheprojectwillbethedefinitionofasampleofgalaxieswithsuitablelineobservations.ThefirstobservationsthatwewillconsiderareKMOS/MUSEdatafromtheVLTandALMAdata.TheESOandALMAarchivesalreadycontainhundredsofobservationsthatcanbeusedtostudythegasdynamicsfromz~0.5toz>4.Ifnecessary,thesedatawillbeintegratedwithCOobservationsfromtheVLAarchive.Next,thestudentwillfamiliarizewithobservationaltechniquestoderiverotationcurvesinparticularwiththesoftware3DBarolo(DiTeodoro&Fraternali2015).Thissoftwarefitsa3Drealizationofatilted-ringgalaxymodeltoemissionlinedatacubesandreturnstherotationandintrinsicdispersionasafunctionofradius.The3Dapproachassuresafullcontroloftheobservationaleffectsthattendtoenhancethedispersioninlow-resolutiondata.ThePhDstudentisexpectedtomodifythesoftwaretoincludeatreatmentforthescaleheightofthegasandthedecompositionofthefinalrotationcurveintomasscomponents.Finally,theevolutionofthedispersionandscalingrelationsasafunctionofredshiftwillbedeterminedandcomparedwiththeoreticalpredictions.AttheendofthePhD,thestudentwillhaveadeepexpertisein3Ddataanalysisandanin-depthunderstandingofthepotentialtheoryofgalaxies.Contacts:[email protected]:Wisnioski,E.,FörsterSchreiber,N.M.;Wuyts,S.etal.2015,ApJ,799,209DiTeodoro&Fraternali2015,MNRAS,451,3021


“Interactionbetweenradioplasmaandhotgasingalaxyclusters”

Supervisor: Myriam Gitti ([email protected])

PhDprojectinASTROPHYSICSTitleoftheProject:InteractionbetweenradioplasmaandhotgasingalaxyclustersSupervisor:MyriamGitti(DIFA)Co-Supervisors:G.Brunetti(INAF),F.Brighenti(DIFA),G.Giovannini(DIFA)ScientificCase:The present project is a study of the interaction between the thermal intra-clustermedium(ICM)andtherelativisticplasmainclustersofgalaxiescharacterizedbyshortcentral cooling time and high central brightness peak, the so-called `cool-core’ (CC)clusters. The knowledge about this interaction is essential to investigate the differentphysical processes acting in the ICM, with particular relevance to the competingprocessesofradiativecoolingandheating,andrelativisticparticleacceleration.Ithaslongbeenrecognized(e.g.,Fabian1994)thathotgasingalaxyclustersmustreachsufficientdensitiestoachievearapidcoolingnearthecenter,afterwhichthepressureoftheoverlyinggasshouldestablishasustainedinwardcoolingflow.Althoughnumerousgalaxy clusters do show the expected sharp peaks of strong X-ray emission, theconsequencesof largemassfluxesincoolingflows(e.g.,burstsofstarformation)havenot been observed in the expected amount. It has become clear that theremust be aheating mechanism that prevents CCs from establishing cooling flows at the ratespredicted.Thesourceof thisheating,andunderstandingwhenandhowit takesplace,hasbecomeamajortopicofstudyinextragalacticastrophysics.Themostpromisingcandidatehasbeenidentifiedasfeedbackfromenergyinjectionbythe central active galactic nucleus (AGN), manifesting in highly disturbed X-raymorphologies (cavities, filaments, shocks and ripples)whichoften correlateswith themorphologyofradiojetsandlobes(e.g.,forreviews:McNamara&Nulsen2007;Gittietal.2012).Thisradio-modefeedbackhasawiderangeofimpacts,fromtheformationofgalaxies to the regulation of CCs which explains why cooling and star formation stillproceedatareducedrate.Insomecases,thepowerfulradiogalaxiesatthecenterofCCclustersaresurroundedbydiffuseradioemissiononscales200-500kpc.Theseradiosources,generallyreferredtoas radio `mini-halos’ (MHs), are synchrotron emission from GeV electrons diffusingthrough μGauss-magnetic fields. Although the central radio galaxy is the obviouscandidate for the injection of the population of relativistic electrons, the diffuse radioemissionofMHsisdifferentfromtheextendedlobesmaintainedbyAGN,andislikelytobe trulygenerated fromthe ICMon largerscales,where the thermalandnon-thermalcomponentsaremixed.Theproblemof theoriginofMHs stems from the fact that the timenecessary for theemitting electrons to efficientlydiffuseon the scales coveredby the radio emission islonger than their radiative lifetime. In the case of MHs this can be explained in theframework of leptonic models, which envision in situ particle re-acceleration byturbulence in the CC region, or alternatively by hadronicmodels, inwhich secondaryelectronsarecontinuouslygeneratedbyproton-protoncollisionsintheclustervolume(e.g.,Brunetti& Jones2014).However, the researchactivityonMHs (both theoreticaland observational) is still unripe, leaving several fundamental questions about thephysicsofthesesourcesunresolved.

AnimportantopenquestionistheoriginofMHsandtheirconnectionwiththeheatingof thegas inCCclusters. In leptonicmodels(Gittietal.2002,2004)turbulence inCCsmay be generated by several mechanisms, including the interplay between theoutflowingrelativisticplasmainAGNjets/lobes,andsloshinggasmotions(Fujitaetal.2004;Heinzetal.2006;Mazzotta&Giacintucci2008;ZuHoneetal.2013;Zhuravlevaetal.2016).Interestingly,turbulencehasbeenmeasuredinthePerseusclusterbyHitomi(HitomiCollaboration2016)withproperties(strengthandscales) thatarecompatiblewith those necessary to explain the origin ofMHswith leptonicmodels. At the sametime,turbulentdissipationinCCshasbeeninvokedasanimportantplayertoheatthegas and balance its radiative cooling. This raises the fascinating possibility, that werecentlyexploredinBravietal.(2016),ofacommonoriginofradioMHsandgasheatinginCC,providedthatthedissipationofthesameturbulenceischannelledpartlyintogasheatingandpartlyintoparticlereacceleration.AnotheropenproblemistheconnectionbetweenMHsandgasdynamicsoftheCCsandofthehostingclustersmorebroadly.Infact,signaturesofminordynamicalactivityhavebeendetectedinanumberofclustershosting MHs (Gitti et al. 2007; Cassano et al. 2008) and a morphological connectionbetweenMHsandcoldfrontshasbeenshowninseveralcases(Mazzotta&Giacintucci2008;Giacintuccietal.2014a,Gendron-Marsolaisetal.2017).Unfortunately, current observations of MHs do not allow us to address these openquestions.Obviously,oneproblemisthelimitedstatisticsthatpreventustodrawfirmconclusions on the connection between thermal and non-thermal phenomena in CCs.Forthisreason,weinvestigatedwhatisthetypicallocationofMHstoselectappropriateX-rayclustersamplessuitedforradiofollow-up.We thus propose an innovative PhD program based on the analysis of X-ray selectedclustersobservedwiththeJanskyVeryLargeArray(JVLA),anSquareKilometreArray(SKA) pathfinder. The synergy of sensitive radio observations and accuratedeterminationsoftheclustercorethermodynamicsiskeytoestablishtheMHorigin.OutlineoftheProject:Inthepresentprojectweplantoinvestigatethelinkbetweenthermalandnon-thermalcomponentsoftheICMinsamplesofCCclustersthatarelikelytohostradioMHs.WealreadyselectedafirstsampleofcandidateMHclustersbycross-checkingX-rayandradiocatalogues.Forthesegalaxyclusters,werequestedandobtainednewJVLAradioobservationsthatwillbeanalyzedinthefirstyearofthePhDproject.DuringthefirstyearwewillalsoaimatfurtherextendingthesampleofknownMHsbyproposing for a systematic radio follow-up with the JVLA of X-ray selected clustersamples,undertheassumptionthateveryMHfollowstheobservedcorrelationbetweenradiopowerandX-rayluminosity(Gittietal.2015).Inthesecondandthirdyearoftheprojectwewillthenconductadetailedinvestigationof the non-thermal properties of MHs and central radio galaxy, while jointlyinvestigatingtheICMX-raypropertiesoftheclustercorethermodynamicsbymeansofarchivalorproprietaryChandradata.This combined, multi-wavelength approach is necessary to understand the radio MHphysicaloriginandtheconnectionwiththeAGNfeedbackprocess.As a part of this PhD project,we also aim at selecting individual targets (such as theprototypePerseuscluster,butalsoRBS797andAbell2626,tonameafew)tobeusedas `case-studies’ forapoint-to-pointcorrelationof ripples inX-raysandradiosurfacebrightness. Suchpioneering investigationswill representabenchmark for future studieswithSKA-AthenasynergiesintheresearchfieldoftheradioMHsinparticular,andoftheinterplaybetweennon-thermalandthermalclustercomponentsingeneral.Contacts:[email protected]

DIFA(UNIBO) – Project 8 “Identificationandphysicalpropertiesofunidentifiedgamma-raysourcesfrom

VLBIobservations.”

Supervisor:GabrieleGiovannini([email protected])

PhDprojectinASTROPHYSICSTitleoftheProject:Identificationandphysicalpropertiesofunidentifiedgamma-raysourcesfromVLBIobservations.Supervisor:Prof.G.GiovanniniScientificCase:TheFermiLATcollaborationisintheprocessofpreparinganewcataloguethatwillusethefirst7yearsofdatafromthesatellitemission.Thislistcontainsmorethan5000pointsources,andupto44%ofthem(~2200sources!)arecurrentlyunassociated.Thenatureofthesesourcesisunknown.Toidentifythesesourcesisimportant,someofthemmaybepeculiarmemberofknownclasses:iftheyareblazars,theymighthavebeenundetecteduntilnowbecausetheyareverydistant(thususefulprobesofthehighredshiftUniverse),intrinsicallyweak(andthereforeinadifferentaccretionregimeofthecentralsupermassiveblackhole,SMBH),oronlyrecently‘awakened’(providingimportantconstraintsonthedutycycleoftheSMBHactivity).Whatisanefficientwaytopickouttherightone?Severalphysicalmethodshavebeenproposed.However,thesemethodsarebasedonexisting,relativelyshallow,multi-frequencysurveys,andcannotbeextensivelyappliedtotheentirepopulationofunassociatedFermisources.WehavestartedaprojecttosurveytheregionsofFermiunassociatedsourceswithasmallandflexibleVLBIarray.ThecoreofthisarrayiscomposedoftheINAF32mradiotelescopesinMedicinaandNoto,andadditionalbaselinesareformedtodishesinSpain,Poland,andLatvia.Wehavesuccessfullyrunsomepreliminarytests.Observingtimeforover400hourshasbeenallocatedforamassiveprojectoverthenext6-12months.Bytheendof2017,weexpecttohaveobservedeveryunassociatedFermisourcenorthofdeclination-20deg.Duringthefirstyear,thePhDstudentisexpectedtobecomefamiliarwiththeVLBItechniqueandtostarttheanalysisofthedataalreadyacquired.Inthesecondandthirdyearsoftheproject,thePhDcandidatewillexploitthisrichdatasettoextractinformationaboutthephysicsofgamma-raysources.Thistopichasimportantimplicationsonthephysicalpropertiesandonthehighenergyemissionmechanismsinrelativisticjets.Despitebeingatthemostextremeendsoftheelectromagneticspectrum,radiowavesandgammaraysareoftenproducedinco-locatedregions,whichprovidesanaturalconnectionbetweenthesetwowindows.Forthisreason,thistopicisexpectedtoremainofgreatimportanceaswemovetowardstheSquareKilometreArray(SKA)andCherenkovTelescopeArray(CTA)era.Indeed,thePhDcandidatewillalsohavetheopportunitytoworkwithdatafromSKAprecursors,suchastheTheGaLacticandExtragalacticAll-skyMWAsurvey,whichwillprovidecomplementarylowfrequencyinformationaboutthepresenceofextendedemissioninblazars.Moreover,astronginternationalcollaborationwithKorea(KASI)andJapan(NAOJ)isactiveonthetopicsofrelativisticjetsandVLBI,whichprovidesalivelyandopenenvironment,withfrequentopportunitiestointeractwithscientistsfromdifferentcountries.ThePhDcandidatewillhavethepossibilitytospendasignificantamountoftime(3-12months)inoneofthecollaboratinginstitutes.AsthethesiswilllargelybebasedonobservationsacquiredwiththeINAFradiotelescopeinMedicina(Bologna)andcorrelatedwiththesoftwarecorrelatorinBologna,thereisapotentialforinterestbythelocalcommunityandforoutreachactivities.

Contacts:GabrieleGiovannini–[email protected]@ira.inaf.it.GabrieleGiovanniniiscorememberoftheSKA-VLBIgroupandmemberoftheCTAextragalacticWG.HeisthePIofthescientificcollaborationbetweenItalyandJapanforVLBIstudies.Projectwillbeincollaborationwith:Dr.MarcelloGiroletti(IRA/INAF),Dr.MonicaOrienti(IRA/INAF),Dr.FilippoD’Ammando(DIFA);Dr.Schinzel(NRAO,USA),Dr.Petrov(Astrogeocentre,USA),Dr.Taylor(AlbuquerqueUniv.,USA).

DIFA(UNIBO) – Project 9 “TowardstheSKAandCTAera:discovery,localization,andphysicsoftransient

sources”

Supervisor:GabrieleGiovannini([email protected])

PhDprojectinASTROPHYSICSTitleoftheProject:TowardstheSKAandCTAera:discovery,localization,andphysicsoftransientsourcesSupervisor:Prof.G.GiovanniniScientificCase:FromourGalaxyouttohighredshift,beyondwherewecanobserveanyotherobject,transientsourcesarerichastrophysicallaboratoriesandinvaluableprobes.Theemissionmechanismsatworkintransientsourcesproduceradiationofvariableenergydependingonthesourcetypeandontheeventphase.BoththeSquareKilometreArray(SKA)andtheCherenkovTelescopeArray(CTA)arethereforefundamentalandideallysuitedtopermittremendousadvancementinthefieldoftransients.Inpreparationforthesetwomajorinternationalprojects,theflexibilityofanItalianVeryLongBaselineInterferometry(VLBI)networkprovidesanidealresourcetoaddressphysicallydifferentclassesoftransients,frombinaries,togamma-raybursts,possibleelectromagneticcounterpartsofgravitationalwaveevents,fastradiobursts,andmore.Dependingonthesourcetype,theoutcomeofaradioobservationcoulddeliveralocalizationorameasureoftheluminosityofamulti-wavelengthormulti-messengertransient,oradetailedstructuralimagingandphysicalanalysisofabinarysystem.TheItalianVLBIobservationsarecomplementedbydedicatedfullarrayfollowupsandmulti-wavelengthobservations,particularlyingammaraysthankstothedatacontinuouslyreceivedbytheFermiLargeAreaTelescope.OutlineoftheProject:Duringthefirstyear,thePhDstudentwillacquirethefundamentalsoftheradiointerferometrytechniqueandofVLBIinparticular.Aftertheinitialstage,afirstoutstandingtransientwillbeanalyzed:thespectaculargiantflareofthebinarysystemCygnusX-3observedinApril2017.Thisisarareandextremevariabilityevent,forwhichwehavetwoepochsofobservationsfromtheEuropeanVLBINetwork.Theeventwillprovideimportantinformation,incombinationwiththemulti-wavelengthhighenergydata,aboutthephysicsofrelativisticjetsandtheaccretion/ejectioncouplinginblackholepoweredsystems.

Atthesametime,wewillcontinuetocollecttriggersfromourvariouscollaborations(ourteamhasrepresentativeswithintheFermi-LATcollaboration,theLigo-Virgocollaboration,andcontactswithabroadcommunityobservingtransientsinvariousbands).Thiswillprovidefurthereventsanddatasetstobefollowedup,suchasfastradiobursts(e.g.Girolettietal.2016,A&A)orgamma-raybursts(e.g.Nappoetal.2017,A&A).TheseneweventswillbethesubjectofactivitiesinthesecondandthirdyearsofthePhD.Abetterunderstandingofthetransientskywithpresentinstrumentationisafundamentalstepforthecharacterizationofthestrategiesforfutureinternationalprojects,suchasSKAandCTA.Therefore,inthesecondandthirdyears,alsosimulationsfortheeventratesandcomparisonstoSKA/CTAperformanceswillbecarriedoutbythecandidate.

ExperiencesabroadinthecontextofVLBIstudies(inparticularatJIVEintheNetherlandsandatKASIinSouthKorea)andofgamma-rayobservations(egatStanfordUniversityintheUSA)willbeencouragedandfinanciallysupported.

Contacts:GabrieleGiovannini–[email protected]@ira.inaf.it.GabrieleGiovanniniiscorememberoftheSKA-VLBIgroupandmemberoftheCTAextragalacticWG.Projectwillbeincollaborationwith:Dr.MarcelloGiroletti(IRA/INAF),Dr.MonicaOrienti(IRA/INAF),Dr.FilippoD’Ammando(DIFA);Dr.EliseEgron(INAF/OAC);Dr.ZsoltParagi(JIVE-NL).


“WeakGravitationalLensingwiththeLyman-alphaForest”

Supervisor:R.BentonMetcalf([email protected])

PhDprojectinASTROPHYSICS TitleoftheProject:WeakGravitationalLensingwiththeLyman-alphaForest Supervisor:R.BentonMetcalf ScientificCase: Oneofthemostimportantquestionsincosmologyandfundamentalphysicstodayisthenatureofdarkenergy,orthecosmologicalconstant,whichiscausingtheexpansionoftheUniversetoaccelerate.Weakgravitationallensinghasbecomeoneofourmostimportantprobesofcosmologyandofthisprobleminparticular.Therearemanyplannedandcurrentsurveysthatwillmeasureweaklensingusingthedistortionthislensinghasontheimagesofdistantgalaxies.ThisisoneoftheprimarygoalsoftheEuclidsatellitemissionforexample.WeaklensinghasalsobeenmeasuredusingtheCosmicMicrowaveBackground(CMB)asasource.ThesemeasurementswillputnewconstraintsondarkenergyandpossiblemodificationstoGeneralRelativityonlargescales. WehaverecentlydiscoveredthatweaklensingshouldbemeasurableusingobservationsoftheLyman-alphaforest–theabsorptionoflightcomingfromquasars,orgalaxies,bydiffusehydrogenthroughtheLyman-alphaline.ThenecessaryLyman-alphaforestdataforthismeasurementisnowbeingobtainedbyspectroscopicsurveysofgalaxiesandquasarswithotherpurposesinmind–surveyslikeeBOSS,DESIandCLAMOTO.Wewillhaveaccesstothisdatathroughcollaboratorswithinsomeofthesurveys.Thismethodwouldprovideameasurementofthecosmologicalgravitationallensingforsourcesataredshift(z~2-3)thatisnotaccessiblewiththetraditionalgalaxybasedmethods(z~0.3–1.5)andthuswouldaccessadifferentregionofmodelparameterspace.Bycross-correlatingthesignalwithforegroundsurveysofdifferentkinds(visible,x-ray,lensing,etc.)additionalinformationcouldbegainedabouttheformationofstructuresintheUniverseandthenatureofdarkmatter. OutlineoftheProject: Thegoalwouldbetodetectgravitationallensingusingthisnewmethod.Wehavewrittentwopapersdemonstratingthatthesignalshouldbestrongindatasetsthatwillbeavailablewithinaboutayear–alargenumberofhighqualityspectraareneededforhighredshiftsourcesthatareasdensonthe

skyaspossible.ThefirsttaskwouldbetodeveloptheanalysissoftwareinPythonand/orC++toanalyzethedata.Wehaveimmediateaccesstodatafordevelopingthismethodandthedatawillincreaseasthesurveyscontinue.Themathematicalformalismfordoingthisisbeingdevelopednow.ThestudentwouldneedtobecomfortablewritingcomputercodeandwithmathematicsandwillneedtobecomeintimatelyfamiliarwithspectroscopicdataandthetechniquesusedtoanalyzetheLyman-alphaforest.Oncethesignalisdetectedtherewouldbemanypossibleprojectstobedoneoninterpretingitandrelatingittoothercosmologicalprobes.Thisprojecthasahighpotentialformakinganimpactoncosmologyifsuccessful,butitisverynewandthereissomeriskalthoughallindicationsarethatitwillbeconsiderablyeasiertoachievethanweaklensingusinggalaxyimagingsurveys.ItislikelythatthestudentwouldworkcloselywithourcollaboratorsintheUnitedStatesandelsewhere. Contacts: R. Ben Metcalf email: [email protected] office: 4S5 Phone: +39 320 4794746 DIFA, Dipartimento di Fisica e Astronomia Alma Mater Studiorum Universita di Bologna via Gabetti 93/2 40129 Bologna Italy

DIFA(UNIBO) – Project 11 Formationanddynamicalevolutionofcosmiclarge-scalestructuresasatestfor

Fundamentalphysics

Supervisor:LauroMoscardini([email protected])

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!PhD$project$in$ASTROPHYSICS$$$Title$of$the$Project:$$Formation)and)dynamical)evolution)of)cosmic)large4scale)structures)as)a)test)for)fundamental)physics)$Supervisor:$Lauro!Moscardini!([email protected])!$Scientific$Case:$$The! standard! cosmological! model! has! provided! a! surprisingly! simple! framework! to!describe!and!accommodate!the!vast!majority!of!observational!data!with!ever!increasing!accuracy!and!statistical!significance!that!have!been!collected!over!the!past!two!decades.!Nonetheless,! the! recent!outcomes!of!particle!physics! experiments! (such!as! the!LHC!at!CERN)! failing! to! detect! any! signature! of! supersymmetry! have! raised! significant$concerns$ on$ the$ fundamental$ nature$ of$ one$ of$ the$ major$ ingredients$ of$ the$standard$cosmological$scenario$A$the$Cold$Dark$Matter!G!normally!associated!with!a!Weakly!Interacting!Massive!Particle!(WIMP)!arising!as!a!supersymmetric!partner!of!the!standard!model!bosons.!Similarly,!the!recent!observational!tensions!between!the!bestGfit!cosmological! parameters! derived! through! the! analysis! of! the! temperature! and!polarisation! anisotropies! of! the! Cosmic!Microwave! Background! radiation! obtained! by!the!Planck!satellite!mission,!and!the!constraints!obtained!on!the!same!parameters!from!local!observational!probes,!have! led!to!speculations$about$possible$deviations$from$the$expected$behaviour$of$ the$other$main$ ingredient$of$ the$standard$model:$ the$cosmological$constant$Λ.!In!such!a!context,!and!with!the!advent!of!the!epoch!of!soGcalled!Precision!Cosmology,!a!detailed! investigation! of! alternative! cosmological! models! and! of! their! impact! on! the!formation! ! and! evolution! of! cosmic! structures! is! essential! for! a! thorough! comparison!between!theory!and!observations!and!to!allow!a!sensible!interpretation!of!any!possible!further! signature! of! a! failure! of! the! standard! cosmological! scenario.! In! this! respect,!cosmological$ simulations$ play$ a$ crucial$ role,! opening! a! window! on! observable!properties!which!cannot!be!predicted!using!analytical!or!simple!linear!numerical!codes,!and! will! represent! an$ essential$ tool$ for$ exploiting$ at$ best$ future$ high$ quality$observations.!$Outline$of$the$Project:$The! PhD! student! will! work! on! developing$ highly$ efficient$ and$ sophisticated$numerical$ tools$ to$ extend$ current$ cosmological$ simulations$ codes$ in$ order$ to$include$the$effects$of$a$variety$of$nonAstandard$cosmologies.!Such!work!will!build!on!top!of! the!already!existing!modifications!developed!over! the!past!decade! to! include! in!numerical! algorithms! several! models! of! Dark! Energy,! Modified! Gravity,! nonGstandard!Dark!Matter! particle! candidates! (such! as! the! Axion! and! SelfGInteracting! Dark!Matter)!and!nonGstandard!primordial! perturbations.!However,!several$ other$ interesting$and$still$competitive$alternative$scenarios$have$not$yet$been$implemented$into$any$of$the$major$ simulation$ codes,! and! therefore! still! represent! an! open! challenge! for! the!computational! cosmology! community.! Just! to! mention! some,! the! Clustering$ Dark$Energy!model!and!various!types!of!Modified!Gravity!screening!(such!as!the$KAmouflage$

scenario)!have!not!been!tested!yet!in!the!nonGlinear!regime!and!may!provide!possible!solutions!to!the!aforementioned!observational!tensions.!!!More!specifically,!the!student!will:!G develop$highly$scalable$and$memory$efficient$modules!of!the!Gadget3!code!for!one!between!the!Clustering!Dark!Energy!and!KGmouflage!models;!

G test,$ validate,$ and$optimise! such! codes! on! ever! increasingly! large! supercomputing!facilities,! reaching! the! level!of! scalability! required!by!TierG0! infrastructures! (such!as!the!Marconi!supercomputer!at!CINECA)!

G Run$largeAscale$and$highAresolution$simulations!for!the!selected!model!and!test!the!code!performance!for!large!production!runs!

G Analyse$ the$ results$ of$ such$ simulations,! with! a! particular! focus! on! the! main!observables! that!will!be! tested!by!upcoming! largeGscale!surveys!such!as!Euclid,!SKA,!LSST:! 2Gpoint! and! 3Gpoint! correlation! function;! abundance! of! clusters! and! of! other!classes!of!objects!with!different!levels!of!bias!(such!as!LRGs!or!quasars);!weak!lensing!statistics!and!cross!correlation!with!clustering!statistics;!CMB!lensing!and!Integrated!SachsGWolfe!effect;!strong!lensing!statistics!and!derived!density!profiles!for!individual!selected!objects;!structural!and!dynamical!properties!of!dark!matter!halos!of!different!masses;!intensity!mapping!of!the!diffuse!neutral!hydrogen!gas,!and!flux!power!of!the!interGgalactic!medium;!hydrodynamical!properties!of!galaxy!clusters;!abundance!and!structure!of!cosmic!voids;!

G Disseminate$ the$ final$ results! to! the! community! through! a! series! of! dedicated!publications!and!presentations!at!international!conferences!

$Contacts:$Marco!Baldi!([email protected])!


“Optimisingthedetectionofgalaxyclustersandtheircosmologicalexploitationinfuturespace-basedsurveys”


!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!PhD$project$in$ASTROPHYSICS$$$Title$of$the$Project:$$Optimising the detection of galaxy clusters and their cosmological exploitation in future space-based surveys!$Supervisor:$Lauro!Moscardini!([email protected])!$Scientific$Case:$$Current and future wide-field photometric surveys (e.g. KiDS, LSST, Euclid, …) will provide the opportunity to increase dramatically the number of known clusters of galaxies, and explore new regimes at low mass (M ~ 10^14 M_sun) and high redshift (z >~ 1). The scientific interest for these new samples of galaxy clusters is two-fold. On one side, the abundance and clustering of these structures constrain cosmology, because the cluster population bears the imprints of the statistical distribution of initial fluctuations, their subsequent growth and the dynamics of the collapse of dark matter halos. On the other hand, the population of these clusters will be a unique laboratory where to study the evolution of galaxies in dense environments at various epochs. In order to obtain a robust and well-defined sample of galaxy clusters from photometric data, it is necessary to use sophisticated methods that distinguish genuine physical groups from clumps generated by chance alignments and non-collapsed overdensities due to the matter distribution on larger scales. When extending the search beyond z = 1, it is necessary to face the limited knowledge of the appearance of clusters at that cosmic epoch and their likely more diverse nature with respect to an analogue low-z ensemble, which make traditional “red-sequence” finders unsuitable. Moreover, it is important to obtain for each cluster detection a mass proxy from the observed galaxy population, which should have a well-behaved relation with the total mass of the cluster, as estimated with other techniques (lensing, X-ray, SZ).!$Outline$of$the$Project:$The project will be based on the cluster finder code AMICO (Adaptive Matched Identifier of Clustered Objects), developed in Bologna by F. Bellagamba and M. Roncarelli. AMICO is based on the Optimal Filtering technique, which allows to maximise the signal-to-noise ratio of the clusters. AMICO has been selected as the first cluster detection code by the Euclid Consortium, is currently being used inside the KiDS collaboration and their developers are members of LSST. The PhD project will consist of several steps. • Optimisation of AMICO in view of future applications: refinement of the estimation

of cluster properties, evaluation of the most appropriate band(s) for the detection, possibility to adapt a scalar-adaptive approach (i.e. not fixing the size of the filter), combination with weak lensing data ...

• Application of AMICO to galaxy catalogs from ongoing and upcoming surveys, with different depths, bands and redshift coverage. These include proprietary KiDS data, and public SDSS and CFHTLS data. This will allow the detection of

previously unknown clusters as well as the comparison with outputs of other algorithms in well-studied fields.

• Evaluation of the scaling relation between the mass proxy derived by AMICO from the galaxy population and the “true” mass as estimated with other methods. Understanding how this relation depends on redshift and on the observing bands is key for the exploitation of the cluster sample.

• Analysis of detected clusters and their members to study galaxy evolution in clusters, e.g. the build-up of the red passive population as a function of redshift and mass. Differently from other methods, AMICO can detect structures without imposing a color selection, and allowing an unbiased estimation of the properties of the members.

• Extraction of cosmological constraints from abundance of detected structures. Their number as a function of mass and redshift depends on Omega_m and sigma_8, as well as on the equation of state of dark energy. Additional constraints can be derived from the self-correlation (clustering) of the cluster distribution.

• Study of the formation of dark matter halos and its dependence on halo properties. Recently, there have been claims of the observation of the so-called assembly bias, i.e. a correlation between large-scale clustering and small-scale properties of the halos. This can be verified in available data-sets with AMICO detections and members.

$Contacts:$Fabio!Bellagamba!([email protected])!!!!!!!!!!!!!!!!!!!!!!Mauro!Roncarelli!([email protected])!


“ClusteringandWeakLensingsignals:fromNumericalSimulationsto

ApproximateMethods”


!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!PhD$project$in$ASTROPHYSICS$$$Title$of$the$Project:$$Clustering+and+Weak+Lensing+signals:+from+Numerical+Simulations+to+Approximate+Methods+$Supervisor:$Lauro!Moscardini!([email protected])!$Scientific$Case:$$At!the!light!of!ongoing!space;based!observational!campaigns!and!considering!the!expectations!from!future!wide;field!surveys!of!galaxies!like!LSST!and!Euclid,!the!goal!of!this!project!is!the!development!of!a!new!method!to!optimize!the!correlation!of!the!signal!between!clustering!and!weak!lensing!in!a!way!to!shade!more!light!into!the!dark!components!of!the!universe:!dark!matter!and!dark!energy.!As!main!outcome,!the!project!is!expected!to!deliver!what!is!the!best!strategy!to!disentangle!non;standard!cosmological!models!using!correlation!function!!and!weak!gravitational!lensing!signals!analyzing!numerical!simulations!and!adopting!approximate!N;body!methods.!$$Contacts:$Carlo!Giocoli!([email protected])!!$$$$$$$$$$$$$$$$$$$$Federico!Marulli!([email protected])!!!


“Towardsafullcosmologicalexploitationofcosmicvoids”


!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!PhD$project$in$ASTROPHYSICS$$$Title$of$the$Project:$$Towards a full cosmological exploitation of cosmic voids!$Supervisor:$Lauro!Moscardini!([email protected])!$Scientific$Case:$$Cosmic!voids!are!large!underdense!structures!that!fill!a!significant!volume!fraction!of!the!Universe.!Their!great!potential!as!a!cosmological!probe!for!constraining!dark!energy!and!testing!theories!of!gravity!has!been!largely!demonstrated.!However,!there!is!no!general!consensus!on!how!to!define!these!objects.!This!represents!one!of!the!main!issues!in!their!cosmological!usage.!For!instance,!in!most!cases!the!size!function!of!cosmic!voids!detected!in!galaxy!redshift!surveys!cannot!be!compared!directly!to!theoretical!predictions,!due!to!the!different!void!definitions!adopted!in!observational!and!theoretical!studies.!The!main!goal!of!the!project!is!to!fill!this!gap,!improving!both!the!algorithms!for!void!identification!and!the!models!for!their!cosmological!interpretation!in!the!perspective!of!future!galaxy!surveys!like!Euclid.$$Outline$of$the$Project:$The!main!steps!of!the!plan!of!the!project!are:!

I improvements!of!an!already!existing!code!for!void!identification!based!on!dynamical!criteria!

I validation!of!the!code!on!cosmological!simulations!starting!from!different!cosmological!models!

I improvements!of!the!theoretical!model!for!void!counts!and!validation!on!simulations!

I application!to!existing!catalogues!of!galaxies!to!extract!constraints!on!the!main!cosmological!models!

I forecasts!for!future!surveys,!including!Euclid,!using!suitable!mocks!catalogues!$Contacts:$Federico!Marulli!([email protected])!!!


"Merger-drivenevolutionofearly-typegalaxies:kinematicsand

effectivestellarinitialmassfunction"

Supervisor:CarloNipoti([email protected])

PhDprojectinASTROPHYSICSTitleoftheProject:"Merger-drivenevolutionofearly-typegalaxies:kinematicsandeffectivestellarinitialmassfunction"Supervisor:CarloNipotiScientificCase:Observationally,inthepresent-dayUniversethereareindicationsthatthestellarinitialmassfunction,thatisthedistributionofstellarmassesatthetimeofstarformation,mightbenon-universal. Inparticular, an empirical correlation is foundbetween thevelocitydispersion and the stellar initial mass function. Moreover, early-type galaxies areobserved to follow a relatively tight empirical correlation between stellar mass andvelocitydispersion.Thenormalizationofthiscorrelationisfoundtovarywithredshift,inthe sense that, for fixed stellar mass, galaxies at higher redshift have higher velocitydispersion.Fromatheoreticalpointofview,ifanearly-typegalaxyevolvesthroughmergers,itsmass,structureandkinematicsisexpectedtoevolvewithtimeinawaythatdependsonthedetailed properties of its merger history. Moreover, the "effective stellar initial massfunction" (EIMF)of a galaxy assembled viamergers,will be themixtureof the stellarinitialmassfunctionofthestarsformedinsituandofthattheaccretedstellarpopulations.Thisevolutionaryscenarioisalsoexpectedtoleadtogradientsintheradialdistributionsof the (EIMF)ofearly-typegalaxies,a feature thathasbeenobservedat least insomemassiveellipticalgalaxies.OutlineoftheProject:TheaimofthisPhDprojectistoimproveourtheoreticalunderstandingoftheformationandevolutionofearly-typegalaxies,withparticularemphasisontheirkinematicsandpropertiesofthestellarpopulations.InthisPhDprojecttheevolutionofthekinematicsandoftheEIMFofmassiveearly-typegalaxieswillbestudiedtheoreticallywithbothanalyticmethodsandnumericaltools.ThePhDstudentwillhavetoanalyzeexistingN-bodysimulationsofgalaxymergersandtorunandanalyzenewN-bodyandhydrodynamicalsimulationsofgalaxymergers.TheseresultswillbecombinedwiththeresultsofexistingcosmologicalN-bodysimulationstostudythekinematicandEIMFevolutionwithredshiftofapopulationofmassiveearly-typegalaxies.Comparisonwithcurrentandfutureobservationaldatawillrepresentanimportantpartoftheproject.Bibliography:

- BlancatoK.,GenelS.,BryanG.,2016,preprint(arXiv:1612.05658)- NipotiC.,TreuT.,LeauthaudA.,BundyK.,NewmanA.B.,AugerM.W.,2012,

MNRAS,422,1714- PostiL.,NipotiC.,StiavelliM.,CiottiL.,2014,MNRAS,440,610- SonnenfeldA.,NipotiC.,TreuT.,2014,ApJ,786,89- SonnenfeldA.,NipotiC.,TreuT.,2017,MNRAS,465,2397- vanDokkumP.,ConroyC.,VillaumeA.,BrodieJ.,RomanowskyA.,2016,preprint

(arXiv:1611.09859)

Contacts:CarloNipotiDipartimentodiFisicaeAstronomiaUniversitàdiBolognaviaGobetti93/2,Bolognaemail:[email protected]:0512095722webpage:https://www.unibo.it/sitoweb/carlo.nipoti


"DisclosingelusiveanddualAGNthroughmillimeterdata"

Supervisor:CristianVignali([email protected])

Disclosing elusive and dual AGN through millimeter data

Supervisor: C. Vignali (Dipartimento di Fisica e Astronomia, Università di Bologna) Co-supervisors: C. Cicone, P. Severgnini, R. Della Ceca (INAF-Osservatorio Astronomico di Brera, Milano) Research project Experience based on the last twenty years of observations indicates that the search for Active Galactic Nuclei (AGN), especially those characterized by heavy obscuration/weak emission, often requires a multi-wavelength approach; in particular, observations in bands where the contrast between accretion-related and star-formation activity is maximized are needed to disclose AGN activity and, hence, provide a relatively good census of the AGN population across cosmic time. However, also the X-ray band, which is typically well suited to achieve this kind of goals, misses a non-negligible fraction of the AGN population if very weak emission (either due to inefficient accretion or very high obscuration) is observed. The PhD project we propose here relies on the capabilities of ALMA to pinpoint compact emission, possibly associated with an AGN, that is washed out by extended components tracing star formation in the host galaxy. We focus on samples of local interacting galaxies (Vorontsov-Velyaminov et al. 2001; VV01), where the presence of accretion activity is not necessarily already known, to disclose AGN using archival ALMA data. A careful analysis of ALMA continuum data at moderately good resolution in the u-v visibility plane allows compact emission in star-forming galaxies to be clearly distinguished, as recently shown by Cicone et al. (in prep.) in an interacting system (Fig. 1) where a pair of AGN are detected (black contours). A preliminary cross-match of the VV01 sample with the ALMA archive indicates the availability of about 50 systems for which ALMA continuum observations in bands 7,8,9,10 offer the unique opportunity to fulfill our requirements and, hence, to validate our pioneering method to disclose nuclear emission. The VV01 sample has been chosen to maximize the chances of discovering dual AGN; this method would be alternative with respect to those typically adopted (e.g., double-peaked emission-line searches for close-separation pairs). In the sources where evidence for very compact emission from dust is found using the ALMA data, real AGN will be identified and characterized using multi-wavelength data (including optical/near-IR spectroscopy, X-ray spectroscopy, and spectral energy distribution fitting). The PhD student will gain significant expertise in state-of-the-art interferometric data analysis techniques and their interpretation, using some of the best millimeter datasets currently available, coupled to a strong scientific background in the field of AGN and galaxy physics. Finally, we note that the main data to carry out this project are already in public multi-wavelength archives and the proposing team has a long, synergic and consolidated expertise in the fields of interest of this research.

References

• Vorontsov-Velyaminov, B. A., Noskova, R. I. and Arkhipova, V. P., “The catalogue of interacting galaxies by Vorontsov-Velyaminov”, Astronomical & Astrophysical Transactions, 20, 717 (2001; VV01).

Fig. 1: Example of the method proposed in this PhD program: from a high-resolution ALMA continuum image (whose resolution is shown in the bottom left part of the figure), working in the u-v visibility plane allows disclosure of emission from compact regions (the double nucleus marked by the black contours). These compact emitting regions, likely associated with AGN, were not detectable in the original map because of the presence of overwhelming extended stellar emission.


"BlackholeaccretionanditseffectsontheISM"

Supervisor:CristianVignali([email protected])

Black hole accretion and its effects on the ISM

Supervisor: C. Vignali (Dipartimento di Fisica e Astronomia – DIFA, Università di Bologna) Co-supervisors: C. Gruppioni (INAF − Osservatorio Astronomico di Bologna), F. Pozzi (DIFA), G. Lanzuisi (DIFA) Research project The search for and characterization of Active Galactic Nuclei (AGN), especially those characterized by heavy obscuration and/or weak emission, require the adoption of a multi-wavelength strategy. While optical selection is largely affected by extinction, presenting a bias against reddened sources, mid-infrared selection, where the primary radiation of the AGN is re-emitted after having been reprocessed by hot dust, is ideal to disclose obscured/weak AGN. Coupling mid-IR selection with hard X-ray data potentially allows a comprehensive physical picture of AGN emission. In this regard, the extended IRAS 12µm galaxy sample (12MGS; Rush, Malkan & Spinoglio 1993), including 893 mid-IR selected local galaxies, represents an ideal starting catalog to provide a relatively unbiased census of AGN at low redshift, including the most obscured ones. Recently, applying spectral energy distribution (SED) fitting to a sub-sample of 76 12MGS galaxies with Spitzer IRS spectra, Gruppioni et al. (2016) were able to characterize the sources in terms of AGN accretion (e.g., bolometric luminosity) and star formation, making specific predictions for next-generation space-based facilities (i.e., JWST, SPICA). The PhD project we propose here is based on the complete characterization of the nuclear emission of the 76 12MGS galaxies using archival Chandra, XMM-Newton and NuSTAR data, which are available for a significant fraction of these sources. In particular, NuSTAR spectral coverage above 10 keV would allow a proper definition of the intrinsic luminosity of the sources, especially when it is coupled to the lower-energy, higher spatial resolution and higher statistics data typically offered by Chandra and XMM-Newton. This strategy has been recently adopted with good results for a subsample of highly obscured AGN in the 12MGS sample (La Caria et al., in prep.). The innovative aspect of this project relies in combining the limited bias provided by mid-IR selection of AGN with the strength of X-ray spectroscopy. Once the X-ray spectral analysis is carried out, the accretion-related emission from the AGN, corrected for the effect of absorption, will be known with high accuracy. As a second, fundamental step of this project, we plan to use the X-ray luminosity as one of the input parameters to model with Cloudy (a photoionization model code; Ferland 2013) the CO spectral line energy distribution (COSLED; see Fig. 1) for the sources with available CO data in terms of proto-dissociation region (PDR) and X-ray-dominated region (XDR) models, as recently successfully done for two Seyfert galaxies by Pozzi et al. (2017) and Mingozzi et al. (submitted). While PDRs (low-J CO transitions) are excited by star formation, XDRs (high-J CO transitions) typically require the hard ionizing radiation field of an AGN. The analysis of the COSLED would

therefore assess the impact of AGN emission to the molecular gas, as shown in the case of the local Seyfert galaxy NGC7130 in Fig. 1. The PhD student will gain significant expertise in the field of AGN astrophysics, in particular of X-ray spectroscopy, submm/mm data analysis (CO with ALMA/IRAM) and usage of Cloudy. Data will be interpreted taking advantage of the consolidated expertise in the fields of interest of this research guaranteed by the proponents of this project. The main data to carry out this project are already in public archives. References

• Ferland G. J., 2013, Rev. Mex. Astron. Astrofis., 49 !, “The 2013 Release of Cloudy” • Gruppioni C. et al., 2016, MNRAS, 458, 4297, “Tracing black hole accretion with SED

decomposition and IR lines: from local galaxies to the high-z” • Pozzi F., Vallini L., Vignali C., Talia M., Gruppioni C., Mingozzi M., Massardi M.,

Andreani P., MNRAS, 2017, in press, “CO excitation in the Seyfert galaxy NGC7130” • Rush B., Malkan M.A, Spinoglio L., 1993, ApJ Suppl. 89, 1, “The extended 12 micron

galaxy sample”

Fig. 1: Observed CO SLED and best-fitting model for the Seyfert galaxy NGC7130 (Pozzi et al. 2017). The low-J transition (open circles) are taken from the SEST telescope, while the mid/high-J transition levels (filled circles) are from Herschel SPIRE/FTS observations. The CO(6-5) ALMA data is marked as a yellow triangle. The green, blue and red lines correspond to the three model components whose parameters are reported in the legend (two PDRs and one XDR). The black line is the sum of the three components. Shaded colored regions represent the 1σ uncertainties.

DIFA(UNIBO) – Project 18 "BridgingthegapbetweenthepresentandtheSKA.AradiostudyoftheShapley

ConcentrationasapilotsciencecasefortheSKA"

Supervisor:DanieleDallacasa([email protected])

PhDprojectinASTROPHYSICS

TitleoftheProject:BridgingthegapbetweenthepresentandtheSKA.AradiostudyoftheShapleyConcentrationasapilotsciencecasefortheSKA

Supervisors:DanieleDallacasa(DIFA–UniBO),TizianaVenturi(IRA–INAF),SandroBardelli(OABO–INAF),MarioNonino(OATS–INAF)

ScientificCase:

Inthehierarchicalparadigm,largescalestructuresintheUniverseandmassivegalaxyclustersformbymeansofmergerandaccretionprocessesbetweensmallersystems.ClustermergersarethemostenergeticeventsintheUniverse,whoseeffectsarevisibleonawiderangeofcomponents,fromthethermal(gas)andnon-thermal(magneticfieldandrelativisticparticles)constituentsofgalaxyclustersandclusterdarkmatter,downtothemuchsmallerscalesoftheindividualgalaxies.SuperclustersarehenceideallaboratoriestostudythedetailsofmassassemblyintheUniverse,astheoverdensityofclustersandgroupsintheseenvironmentsfavorsmergingandaccretionprocesses.TheShapleyConcentration(SC),whichhasbeendevotedalotofattentionoverthepast30years,istheperfectplacetoaddressthisstudy:itsproximity(meanredshiftz≈0.05)allowstoaddresstheimpactofclustermergers(inparticularminormergershere)ontheevolutionofgalaxiesinclusters,andoftheclustersthemselves.Asamatteroffact,theSChostspristinesmallgroupsaswellasmassiveclustersinanevolveddynamicalstage.Thislargeportionoftheskyhasbeenobservedintheradiobandoverawiderangeoffrequenciesandresolutions,toaddressanumberofquestions,fromthescaleoftheinnerregionsofthegalaxiesintheclusters,tothatofthelarge-scaleemissionassociatedwiththeintraclustermedium.

DuetoitslocationintheSouthernHemisphere,theSCisthenaturaltargetformanySKAprecursors,suchasMeerKAT(locatedinSouthAfricaandoperatingat600-1800MHz),MWA(locatedinWesternAustraliaandoperatingat80-300MHz)andASKAP(locatedinWesternAustraliaandoperatingat600-1800MHz).

OutlineoftheProject:

Weproposeaprojecttobedevelopedintwosteps,assummarizedherebelow

Step1.TheShapleyConcentrationbetweennowandtheSKA

WeaimtoperformamultibandstudyoftheShapleyConcentration,withanumberofgoalsinmind.Inparticulartodisentanglethedetailsoftheaccretionprocessesatplayhere,wewishto:

• Addresspossibleevolutionaryeffectsontheradiopropertiesofgalaxiesinpristineandevolvedenvironments;

• StudytheAGN/ICMfeedbackprocessesinthecentralregionsoftheclustersandgroupsindifferentevolutionarystages;

• Detectdiffuseemissionontheclusterscaleforanunderstandingoftheeffectsofminormergersinthecontextoftheformationofsuchtypeofsources;

• Possiblydetectemissionfromtheinterclusterfilaments.

AsuccessfulstudyisensuredbyourproprietarylargedatabaseofobservationsperformedwiththeGiantMetrewaveRadioTelescope(Pune,India),whichfullycoversthetwomainregionsintheSCcore(severalsquaredegreesinthesky).PartoftheobservationshavejustbeenacquiredwiththeupgradedGMRT(uGMRT),whichisbyallmeansanSKAprecursorsinthelowfrequencydomain.Moreover,theSChasbeenobservedbyuswiththetwoSKAprecursorsKAT-7andMWA.Finally,observationsoftheSChavebeengrantedaspartoftheEarlyScienceofASKAP-EMU,tobestartedinafewmonthsfromnow.Beyondthesciencedelivery,thiswillallowthepotentialPhDstudenttostartdevelopingthenecessaryskillstoreduceandanalyzethedatafromtheSKAprecursors,whichisanessentialsteptowardsthefulluseoftheSKA,onceoperational.

ThesamelargeportionoftheskyhasbeenobservedwithXMM-Newton(PIsGastaldelloandRossetti,INAF-IASFMilano)andChandra(PIsMazzottaandBourdin,Universita’diTorVergata)intheX-ray,withPlanckandwithESO-VST(PIMerluzziandtheShaSSteam,INAF-OANa).Ourongoingcollaborationswiththosegroupsensuresamostsuccessfuloutcome.ThesynergybetweenthelowradiofrequencyandlowradioresolutionandXMM,ChandraandPlanckobservationswillallowthestudyoftheroleofclustermergerandaccretiononthelargescalecomponents(ICManddiffuseclustersscaleradioemission);thesynergybetweenthehighresolutionradioinformationandtheopticaldatasetwillallowthestudyoftheroleoftheenvironmentontheevolutionofgalaxies.

ThisuniquesetofobservationsmakestheproposedstudyanidealpilotprojecttobridgethegapbetweenthepresentradioastronomicalfacilitiesandtheforthcomingSKA.

Step2.PredictionsfortheSKA

Anaturalquestionis:“howfarwouldwebeabletoseeaShapleyConcentrationwiththeSKA?”.Inastrophysicaltermsthismeans:“howfarinredshiftwouldwebeabletofollowtheevolutionofgalaxiesandclustersasconsequenceofclustermergersandaccretion?”.Moreover:“wouldwebeabletodisentangletheroleofenvironmentandevolutionforthegalaxies?”.

TothisaimwewillexploittheresultsobtainedinStep1andcombinethemwiththecurrentstate-of-the-artinformationavailableforthoseCLASHclusters(whoseredshiftrangesfrom≈0.2to≈0.8)withavailablehighsensitivityradioobservationsaspartofourGMRTRadioHaloSurveyandGMRTMACS-PlanckRadioSurvey.TheCLASHclustershaveanexcellentspectro-photometriccoverageouttotheoutskirts,whichensuresconsistencyinourpredictionsbetweenthelow-redshiftdetailedstudyoftheShapleyConcentrationandthehighredshiftCLASHclusters.AnongoingcollaborationwithDott.M.Nonino(INAF-OATs)willensuresuccessinthissecondstep.

Contacts:DanieleDallacasa([email protected]),TizianaVenturi([email protected]),SandroBardelli([email protected]),MarioNonino([email protected])

DIFA(UNIBO) – Project 1 · DIFA(UNIBO) – Project 1 “The effect of AGN feedback on the gas consumption in high-redshift galaxies” Supervisor: Marcella Brusa ([email protected])

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