Title Multifrekvencijska analiza Polarnog plamička Title (english) Multifrequency Analysis of the Polaris Flare Author Ina Galić Mentor Vibor Jelić (mentor)Committee member Vibor Jelić (predsjednik povjerenstva)Committee member Vernesa Smolčić (član povjerenstva)Committee member Matko Milin (član povjerenstva)Committee member Damir Pajić (član povjerenstva)Committee member Mihael Srđan Grbić (član povjerenstva)Granter University of Zagreb Defense date and country 2023-09-05, Croatia Scientific / art field, NATURAL SCIENCES Abstract Međuzvjezdana tvar (ISM) odnosi se na materijal koji ispunjava prostor između zvijezda unutar galaksija. Obuhvaća različite komponente, uključujući prašinu, plin koji postoji u različitim stanjima (hladan, topao ili vruć i ioniziran, neutralan ili molekularan), kozmičke zrake i magnetska polja. Jedan fascinantan oblik ISM-a su molekularni oblaci. Ove guste i hladne strukture služe kao povoljna okruženja za stvaranje novih zvijezda. Cilj ovog rada bio je istražiti interakciju između ionizirane i neutralne materije te magnetskog polja unutar molekularnog oblaka Polarni plamičak. Kako bi to postigli, proveli smo opsežnu analizu radiopolarimetrijskih mjerenja i zračenja detektiranog iz tog područja na više frekvencija. Sinkrotronsko zračenje na radiovalnim duljinama pokazalo se kao koristan alat za proučavanje ionizirane komponente ISM-a. Upotri jebili smo promatranja sinkrotronskog zračenja prikupljena radioteleskopom LOFAR (iz engl. Low-Frequency Array) na niskim radiofrekvencijama i nad njima proveli Faradayevu tomografiju koristeći se tehnikom RM sinteze (iz engl. rotation measure synthesis). Naša analiza je otkrila strukturu difuzne polarizirane emisije koju karakteriziraju ravni depolarizirani kanali. Ovi kanali predstavljaju područja u kojima nema polarizirane emisije. Kako bismo stekli uvid u 3D strukturu lokalnog magnetskog polja i distribuciju različitih vrsta materije unutar oblaka, trebali smo odrediti njihove smjerove. U tu smo svrhu primijenili kotrljajući Houghov transformat na LOFAR-ove slike sinkrotronskog zračenja i mape neutralnog vodika iz HI4PI pregleda neba. Odredili smo i smjer magnetskog polja u ravnini neba iz podataka o polariziranom zračenju zvijezda, koje je RoboPol prikupio pomoću zvjezdane optičke polarimetrije, i promatranja termalne emisije prašine snimljene Planckovim instrumentima. Nakon analize podataka, naši rezultati ukazuju na nedostatak korelacije između smjera depolariziranih kanala i komponente magnetskog polja paralelne ravnini neba. Međutim, intrigantne veze pojavljuju se između drugih komponenti molekularnog oblaka. Konkretno, opažamo da filamenti neutralnog vodika na jednom intervalu brzinama pokazuju isti smjer prostiranja kao pronađeni depolarizirani kanali. Također, postoji preklapanje između smjera prostiranja filamenata neutralnog vodika na drugom intervalu brzina i silnica magnetskog polja koje leže u ravnini neba. Ovi pro- nalasci impliciraju mogućnost da su korelirajuće strukture lokalizirane unutar istog prostornog dijela molekularnog oblaka.
Abstract (english) The interstellar medium (ISM) refers to the material that fills the vast regions of space between stars within galaxies. It encompasses various components, including dust, thermal gas existing in different states (cold, warm, or hot, and ionized, neutral, or molecular), cosmic rays, and magnetic fields. One fascinating form of the ISM are molecular clouds. These dense and cold structures serve as favorable environments for star formation. This study aimed to investigate the interaction between ionized and neutral matter, as well as the magnetic field, within the molecular cloud Polaris Flare. We con ducted a comprehensive analysis of radio polarimetric measurements and radiation detected from the region at multiple frequencies. Synchrotron radiation at radio wavelengths proved to be a valuable tool for studying the ionized component of the ISM. We used observations of synchrotron radiation collected by the Low-Frequency Array (LOFAR) radiotelescope at low radio frequencies and performed a Faraday tomography on them using the rotation measurement (RM) synthesis technique. Our findings revealed a diffuse polarized emission structure characterized by straight depolarization canals. These canals represent regions where the polarized emission is absent. To gain insights into the 3D structure of the local magnetic field and the distribution of different types of matter within the cloud, we wanted to determine their orientations. For this purpose, we applied the Rolling Hough transform to both the LOFAR synchrotron radiation images and the neutral hydrogen maps obtained from the HI4PI survey. We also derived the plane-of-the-sky magnetic field orientations from starlight polarization data, collected by RoboPol using stellar optical polarimetry, and thermal dust emission captured by the Planck instruments. Upon analyzing the data, our results indicate a lack of correlation between the direction of the depolarization canals and the plane-of-the-sky magnetic field component. However, intriguing connections emerge between other components of the molecular cloud. In particular, we observe that the neutral hydrogen filaments at one speed interval show the same propagation direction as the detected depolarization canals. Furthermore, there is an overlap between the direction of propagation of the HI filaments at another speed interval and the magnetic field lines lying in the plane of the sky. These findings imply the possibility that correlating structures are localized within the same spatial portion of the molecular cloud.
Keywords
međuzvjezdana tvar
sinkrotronsko zračenje
depolarizirani kanali
magnetska polja
filamenti neutralnog vodika
Faradayeva tomografija
kotrljajući Houghov transformat
polarizirano zračenje zvijezda
termalno zračenje prašine
Keywords (english)
interstellar medium
synchrotron radiation
depolarization canals
magnetic fields
neutral hydrogen filaments
Faraday tomography
Rolling Hough Transform
starlight polarization
thermal dust emissio
Language croatian URN:NBN urn:nbn:hr:217:346382 Study programme Title: The University Integrated Undergraduate and Graduate Programme in Physics; Research Physics; specializations in: Research Physics Type of resource Text File origin Born digital Access conditions Open access Terms of use Created on 2023-11-23 13:04:22
