Extreme Particle Acceleration in Microquasar Jets and Pulsar Wind Nebulae with the MAGIC Telescopes

268 Pages·2018·15.24 MB·English

by  Alba Fernández Barral

Springer Theses
Recognizing Outstanding Ph.D. Research
Alba Fernández Barral

Extreme Particle
Acceleration in
Microquasar Jets
and Pulsar Wind
Nebulae with the
MAGIC Telescopes
Springer Theses
Recognizing Outstanding Ph.D. Research
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á
Alba Fern ndez Barral
Extreme Particle Acceleration
in Microquasar Jets
and Pulsar Wind Nebulae
with the MAGIC Telescopes
Doctoral Thesis accepted by
ò
the Universitat Aut noma de Barcelona, Bellaterra, Spain
123
Author Supervisor
Dr. AlbaFernándezBarral Dr. Oscar BlanchBigas
CTAO gGmbH (Headquarters) IFAE–BIST
Heidelberg, Germany EdificiCn, Universitat Autònoma
deBarcelona
and Bellaterra (Barcelona), Spain
CTAO gGmbH (Local Office)
Bologna, Italy
and
IFAE–BIST
EdificiCn, Universitat Autònoma de
Barcelona
Bellaterra (Barcelona), Spain
ISSN 2190-5053 ISSN 2190-5061 (electronic)
SpringerTheses
ISBN978-3-319-97537-5 ISBN978-3-319-97538-2 (eBook)
https://doi.org/10.1007/978-3-319-97538-2
LibraryofCongressControlNumber:2018950924
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Allà ets l’essència de tot. Pels crítics, els
paradigmes i els cànons pels que es regien
estan obsolets de cop. Que amb l’aura que tu
desprens s’imposa, de forma urgent, fer una
revisió dels clàssics. Que ets jove eternament.
Els amics de les arts
Museu d’Història Natural
A mis padres, a BRAIS.
Os pertenece cada palabra aquí escrita.
’
Supervisor s Foreword
The birth of gamma-ray astronomy, or astroparticle physics, can be dated back to
1989, when the Crab Nebula was first observed at TeV energies with a
ground-based imaging atmosphericCherenkov telescope. Inlessthan 30years,we
have witnessed many great discoveries and technological advances in this new
field. Dr. Alba Fernández Barral’s thesis adds to this step-by-step evolution, pro-
vidingnotonlyoutstandingphysicalresultsbutalsoaidingthedevelopmentofthe
next generation of Cherenkov telescopes, validating and characterizing several
subsystems of the telescope’s camera.
In order to contribute her two pennyworth to the understanding of different
astrophysical phenomena, the author deepened in the performance, hardware, and
software of the MAGIC telescopes, located in the Canary Island of La Palma. She
also carried out several scientific sojourns to expand her knowledge of different
gamma-ray detection techniques, such as those used by Fermi-LAT and HAWC,
which observe the sky at complementary energy bands alongside MAGIC.
Mainly focused on the physics behind the relativistic jets displayed by micro-
quasars,herworkprovidesacompleteviewofCygnusX-1intheGeV–TeVband.
This source, one of the most famous and well-studied binary systems, lacked of
conclusive information regarding gamma-ray emission processes and relied on
theoreticalhypotheses.WithherworkusingbothFermi-LATandMAGICdata,the
author was able to not only detect the source for the first time in the gamma-ray
band,butalsoprovideconstraintsontheproductionsiteandmechanismthatgives
rise togamma rays within the jets, pointing toinverse Compton on stellar photons
as the responsible process. This allows to limit and even refute different theories,
such as the so-called advection-dominated accretion flow models. Although not
detectedatveryhighenergies,adeepstudyonCygnusX-3andV404Cygniisalso
given, providing a state-of-the-art overview of the best microquasar candidates to
emit gamma rays during exceptional transient jet events.
A population study of pulsar wind nebulae (PWNe) was recently released after
theskyscanperformedbytheH.E.S.S.CollaborationattheinnerpartsoftheMilky
Way.Underthepremisethatthistypeofsourceisthemostnumerousinourgalaxy,
the author coordinated a project analyzing and discussing the data for five optimal
ix
x Supervisor’sForeword
candidates formerly observed by MAGIC, in order to shed light on the particle
acceleration of PWNe at the outer parts of our galaxy. Moreover, while working
withHAWCgroups,shemeticulouslyinvestigatedthebestcandidatesforMAGIC
amongthenewTeVsourcesdetectedandpublishedbyHAWC.Sheledandcarried
out a joint MAGIC, HAWC, and Fermi-LAT project in which the alleged PWNe
nature of three new sources is deeply discussed and the size of each of them
constrained.
Besides the quantity and quality of her work, it is worth stressing Alba’s
involvement on getting those results: She was always leading the analysis, inter-
pretation, and edition as well as coordinating the projects she worked on.
Barcelona, Spain Dr. Oscar Blanch Bigas
July 2018
Preface
Throughout our entire history, we humans have strived to unravel the mysteries
with which the deep universe challenges us. In our humble beginnings, this task
was performed with our naked eyes, by gazing at the stars and planets and won-
dering how far away they were and how they moved in the night sky. For many
centuries, only the visible universe was reachable for us, but extraordinary
achievements were accomplished despite the limited tools: We discovered, for
example, that our planet was not the center of the universe, owing to Nicolaus
Copernicus’ observations and his heliocentric model. From Copernicus’ epoch up
to now, the development of new technologies and the advancement of our own
understanding of the Cosmos allowed us to disentangle many riddles. Fortunately,
this natural curiosity that leads us to improve never ends, and we face new ques-
tions that challenge our capacity as scientists. In the present thesis, I focus on a
small fraction of this science: the gamma-ray astronomy. The bulk of results pre-
sented here was obtained by means of the imaging atmospheric Cherenkov tech-
nique, with the so-called MAGIC telescopes. Once arrived at the earth, a gamma
ray interacts with atmospheric nuclei producing charged particles. The latter can
move faster than the speed of light in air, giving rise to a very fast bluish light,
knownasCherenkovlight.TheimagingatmosphericCherenkovtechniqueisbased
on the detection of that light, from which we can obtain information about the
primary gamma ray. Other gamma-ray detection techniques included in the thesis,
such as satellites or water Cherenkov tanks, have also been proved to play an
important role to disentangle the gamma-ray sky. All these techniques are ener-
getically complementary to each other, helping us to understand deeply the pro-
cesses that take place on different astrophysical sources. This thesis comprises my
effortsonthestudyofparticleaccelerationandgamma-rayproductionmechanisms
inside galactic relativistic jets displayed by microquasars and the shocks produced
in pulsar wind nebulae (PWNe), using in several cases all the aforementioned
detection techniques.
PartIofthethesisencompassesanintroductiontonon-thermaluniverseaswell
as a detailed description of different gamma-ray detectors. First, I delve into the
productionandabsorptionmechanismsthatgovernthegamma-rayemission,along
xi