Neutron stars are predicted to form during the gravitational collapse of massive star cores. They are extremely dense objects supported by neutron degeneracy pressure. Neutron stars have masses around 1.4 solar masses, radii around 10 km, and densities greater than nuclear density. They possess immense gravitational and magnetic fields at their surfaces. Pulsars were discovered in 1967 and provided the first clear evidence that neutron stars exist, rotating rapidly and emitting beams of electromagnetic radiation. Neutron stars manifest themselves observationally in various forms including pulsars, x-ray binaries, magnetars, and thermal x-ray emitters.
NEUTRON STARS - UNIQUE COMPACT OBJECTS OF THEIR OWNIJRST Journal
This paper outlines the study of neutron stars right from the early
theoretical predictions and observations by various astrophysicists which
gradually aroused huge interests among the scientific community, to the
latest developments in the scientific analysis of the behavior of the different
categories of compact objects. Although white dwarfs, neutron stars, brown
dwarfs, Black Holes etc.fall under the category of compact objects, each of
them is unique in its own way.
NEUTRON STARS - UNIQUE COMPACT OBJECTS OF THEIR OWNIJRST Journal
This paper outlines the study of neutron stars right from the early
theoretical predictions and observations by various astrophysicists which
gradually aroused huge interests among the scientific community, to the
latest developments in the scientific analysis of the behavior of the different
categories of compact objects. Although white dwarfs, neutron stars, brown
dwarfs, Black Holes etc.fall under the category of compact objects, each of
them is unique in its own way.
Universe and the Solar System (Lesson 1).pptxJoenelRubino3
SHS Earth and Life Grade 11 Lesson 1. This lesson discusses the compos of the universe, the origin of the universe, different hypotheses of the origin of the universe
CONTENTS
INTRODUCTION
NEED FOR CYBER LAWS
CYBER LAWS IN INDIA
CYBER CRIMES
OFFENCES AND LAWS IN CYBER SPACE
CYBER LAWS AMENDMENTS
CONCLUSION
INTRODUCTION
What is Cyber Law?
Cyber Law is the lawgoverning cyber space.Cyber space is a very wideterm and includescomputers, networks,software, data storagedevices (such as hard disks,USB disks etc), theInternet, websites, emailsand even electronic devicessuch as cell phones, ATMmachines etc.
Cyber lawencompasses lawsrelating to
:
1. Cyber Crimes
2. Electronic and DigitalSignatures
3. Intellectual Property
4. Data Protection andPrivacy
NEED FOR CYBER LAWS
TACKLING CYBERCRIMES
INTELLECTUALPROPERTYRIGHTS ANDCOPYRIGHTSPROTECTION ACT
NEED FOR CYBER LAWS
1. Cyberspace is an
intangible
dimension that is impossible togovern and regulate usingconventional law.
2. Cyberspace has complete
disrespect for jurisdictionalboundaries
. A person in Indiacould break into a bank’selectronic vault hosted on acomputer in USA and transfermillions of Rupees to anotherbank in Switzerland, all withinminutes. All he would need is alaptop computer and a cellphone.
3. Cyberspace
handlesgigantic traffic volumesevery second
. Billions ofemails are crisscrossing theglobe even as we read this,millions of websites are beingaccessed every minute andbillions of dollars areelectronically transferredaround the world by banksevery day.
4. Cyberspace is
absolutelyopen to participation by all.
A ten year-old in Bhutan canhave a live chat session with aneight year-old in Bali withoutany regard for the distance orthe anonymity between them
ABOUT AUTHOR
Sumit Verma
Chitkara University
Undergraduate
PAPERS
1
FOLLOWERS
575
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Contents
Introduction to Pulsar.
Properties of pulsar.
Discovery of pulsar.
Formation of pulsar from neutron star.
Crab pulsar & Binary pulsar.
Mechanism & radiating process of pulsar.
Application & Milestone.
Universe and the Solar System (Lesson 1).pptxJoenelRubino3
SHS Earth and Life Grade 11 Lesson 1. This lesson discusses the compos of the universe, the origin of the universe, different hypotheses of the origin of the universe
CONTENTS
INTRODUCTION
NEED FOR CYBER LAWS
CYBER LAWS IN INDIA
CYBER CRIMES
OFFENCES AND LAWS IN CYBER SPACE
CYBER LAWS AMENDMENTS
CONCLUSION
INTRODUCTION
What is Cyber Law?
Cyber Law is the lawgoverning cyber space.Cyber space is a very wideterm and includescomputers, networks,software, data storagedevices (such as hard disks,USB disks etc), theInternet, websites, emailsand even electronic devicessuch as cell phones, ATMmachines etc.
Cyber lawencompasses lawsrelating to
:
1. Cyber Crimes
2. Electronic and DigitalSignatures
3. Intellectual Property
4. Data Protection andPrivacy
NEED FOR CYBER LAWS
TACKLING CYBERCRIMES
INTELLECTUALPROPERTYRIGHTS ANDCOPYRIGHTSPROTECTION ACT
NEED FOR CYBER LAWS
1. Cyberspace is an
intangible
dimension that is impossible togovern and regulate usingconventional law.
2. Cyberspace has complete
disrespect for jurisdictionalboundaries
. A person in Indiacould break into a bank’selectronic vault hosted on acomputer in USA and transfermillions of Rupees to anotherbank in Switzerland, all withinminutes. All he would need is alaptop computer and a cellphone.
3. Cyberspace
handlesgigantic traffic volumesevery second
. Billions ofemails are crisscrossing theglobe even as we read this,millions of websites are beingaccessed every minute andbillions of dollars areelectronically transferredaround the world by banksevery day.
4. Cyberspace is
absolutelyopen to participation by all.
A ten year-old in Bhutan canhave a live chat session with aneight year-old in Bali withoutany regard for the distance orthe anonymity between them
ABOUT AUTHOR
Sumit Verma
Chitkara University
Undergraduate
PAPERS
1
FOLLOWERS
575
Follow
RELATED PAPERS
Important question answers Information Technology Act, 2000
Suvo Chatterjee
Download
More Options
IT ACT 2000 – PENALTIES, OFFENCES WITH CASE STUDIES From
aru mugam
Download
More Options
Information Technology
trinisha chakroborty
Download
More Options
OVERVIEW OF CYBER LAWS IN INDIA Index
aneesh tvm
Download
More Options
Critical analysis of proposed cyber Crime Bill 2015
Shahid Jamal T U B R A Z Y Cyber Lawyer
Download
More Options
Final Cyber Cri
Prashant Dabhade
Download
More Options
Cyber Laws in India
Vikas Khatkar
Download
More Options
Commentary on THE INFORMATION TECHNOLOGY ACT, 2000
Rohas Nagpal
Download
More Options
INTRODUCTION TO THE ACT 2. NEED AND OBJECTIVES 3 ROLE OF IT IN ECOMMERCE 4 CYBER CRIME 5 ELECTRONIC SIGNATURES 6 E-GOVERNANCE
keshav agarwal
Download
More Options
NON BAILABLE OFFENCES( Cyber Crimes) UNDER The IT Act, 2000 (Cyber Law)
Adv Prashant Mali, Ph.D.
Download
More Options
P a g e Fundamentals of Cyber Law Rohas Nagpal Asian School of Cyber Laws
vijay onlinesangli
Download
More Options
SEMINAR AND WORKSHOP ON DETECTION OF CYBER CRIME AND INVESTIGATION Presented by
chayapathi A R
Download
More Options
Cyber Crime Investigation and Trial Procedure in Bangladesh: Comparison with India
Thohedul Islam Talukdar
Down
Contents
Introduction to Pulsar.
Properties of pulsar.
Discovery of pulsar.
Formation of pulsar from neutron star.
Crab pulsar & Binary pulsar.
Mechanism & radiating process of pulsar.
Application & Milestone.
A brief information about the SCOP protein database used in bioinformatics.
The Structural Classification of Proteins (SCOP) database is a comprehensive and authoritative resource for the structural and evolutionary relationships of proteins. It provides a detailed and curated classification of protein structures, grouping them into families, superfamilies, and folds based on their structural and sequence similarities.
Richard's aventures in two entangled wonderlandsRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Richard's entangled aventures in wonderlandRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
Seminar of U.V. Spectroscopy by SAMIR PANDASAMIR PANDA
Spectroscopy is a branch of science dealing the study of interaction of electromagnetic radiation with matter.
Ultraviolet-visible spectroscopy refers to absorption spectroscopy or reflect spectroscopy in the UV-VIS spectral region.
Ultraviolet-visible spectroscopy is an analytical method that can measure the amount of light received by the analyte.
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...
Neutron stars
1. Neutron Stars
1: Basics
Andreas Reisenegger
ESO Visiting Scientist
Associate Professor,
Pontificia Universidad Católica
de Chile
2. Outline of the Lecture Series
1. Basics: Theory & history: prediction, discovery, etc.
2. Phenomenology: The many observational
“incarnations” of NSs & what we can learn from
them
3. Thermal evolution: Cooling & heating
mechanisms, expected thermal history, obs.
constraints & what they tell us about nuclear physics
& gravity
4. Magnetism: Determination of NS magnetic fields,
their origin, evolution, and related physical processes
3. Outline of Lecture 1
• Degenerate fermions, white dwarfs, &
Chandrasekhar mass
• Prediction of neutron stars, main predicted
properties
• Pulsar discovery & interpretation
4. Bibliography - 1
• Stuart L. Shapiro & Saul A. Teukolsky, Black Holes,
White Dwarfs, and Neutron Stars, Wiley (1983): quite
outdated on the phenomenology, but still the most
comprehensive and pedagogical discussion
• Richard R. Silbar & Sanjay Reddy, Neutron Stars for
Undergraduates, Am. J. Phys. 72, 892-902 (2004;
erratum 73, 286, 2005), nucl-th/0309041: how to build
simple numerical models of neutron stars
• James M. Lattimer & Madappa Prakash, The Physics
of Neutron Stars, Science, 304, 536 (2004): review
• Norman K. Glendenning, Compact Stars: Nuclear
Physics, Particle Physics, and General Relativity,
Springer (1997): quite theoretical
5. Bibliography - 2
• Kip S. Thorne, Black Holes & Time Warps: Einstein’s
outrageous legacy, Norton (1993): entertaining popular
history of the idea of compact stars & black holes
• Bernard F. Schutz, A first course in general relativity,
Cambridge (1985): rigorous, but elementary account of
GR from the basics up to relativistic stars, black holes, &
cosmology
• Soon to appear: P. Haensel, A. Y. Potekhin, & D. G.
Yakovlev, Neutron Stars 1: Equation of State and
Structure (2006)
6. Pauli
principle
Fermions:
• particles of half-integer
spin (½, 3/2, ...):
– electrons, protons,
neutrons...
• obey Pauli exclusion
principle (1925): No more
than 1 fermion can occupy
a given orbital (1-particle
quantum state)
“Fermi-Dirac statistics”
7. Ground state of fermion
system
F
p
p
|
|
3
h
p
p
p
z
y
x z
y
x
m
V
N
n
n
p
p
V
h
N
F
F
,
)
3
(
3
4
2
3
1
2
3
3
Each orbital has a phase-space volume
Ground state of system of N fermions of spin ½ (sz = ½) in a spatial volume V
(“box”):
Ground state (T=0) has all particles in the
orbitals of the lowest possible energy
Fermi sphere in momentum space:
8. Degeneracy pressure
• Fermi energy:
– Max. fermion energy @ T= 0
– Also chemical potential of the system: F = (T= 0)
– General:
– Non-relativistic limit, pF<<mc:
– Extreme relativistic limit, pF>>mc:
• Total energy E: Sum over Fermi sphere (all particles)
• “Degeneracy pressure” P:
– Through kinetic theory or thermodynamics
– Non-zero value at T=0
– Non-relativistic Extreme relativistic
• Zero-temperature limit is good approximation as long as kT << F
– Thermal effects are only a small correction for white dwarfs & neutron stars
2
2
2
2
)
( c
p
mc F
F
3
2
2
2
2
2
)
3
(
2
2
n
m
m
p
mc F
F
3
1
2
)
3
( n
c
c
pF
F
)
(
)
(
P
n
P
V
E
P
N
m
n
P
5
)
3
( 3
5
3
2
2
3
4
3
1
2
)
3
(
4
1
cn
P
9. White dwarfs
Hydrostatic equilibrium
Non-relativistic electron
degeneracy pressure
Combining,
white dwarfs get smaller (denser & more relativistic) as M increases
Relativistic electrons
Combining with hydrost. equil. unique mass
(Chandrasekhar 1931)
4
2
2
~
R
GM
P
r
GM
dr
dP
3
5
3
3
2
3
5
3
2
2
~
5
)
3
(
R
m
M
m
m
n
P
i
e
e
3
4
3
1
3
5
3
2
cm
ton
1
~
km
10
~
~
M
m
Gm
R
i
e
3
4
3
3
4
3
1
2
~
)
3
(
4
1
R
m
M
c
cn
P
i
Sun
2
2
3
har
Chandrasek 4
.
1
)
(
~ M
m
G
c
M
i
11. Neutrons:
decay or not decay?
• In vacuum (lab), neutrons decay with half-life ~ 15 min:
• In very dense matter, neutrons are stable (don’t decay) because low-energy
proton & electron orbitals are already occupied
• “Chemical” (weak interaction) equilibrium
• Around nuclear density, neutrons coexist stably with a much smaller
number (~1%) of protons & electrons (fraction density-dependent &
uncertain)
• At higher densities, strong interactions among particles are difficult to
model, making the state of matter (& eq. of state) more & more uncertain.
e
e
p
n
e
p
n
e
p
n
12. Baade & Zwicky (1934):
“With all reserve we advance the view that supernovae represent
the transition from ordinary stars into neutron stars, which in their
final stage consist of extremely closely packed neutrons.”
Supernova 1987A (23 Febr. 1987) in the Large Magellanic Cloud:
before & after
13. Collapse
Collapse of stellar core
huge density
forces p + e n +
Neutrinos () escape: a
few detected 2 hours
before the light of SN
1987A.
Neutrinos
Remnant
BUT: No neutron star found!
14. Neutron stars
• First approximation: Self-gravitating ball of non-
interacting neutrons at T=0
• Recall non-relativistic white dwarf:
• Neutron star (by analogy / scaling):
3
4
3
1
3
5
3
2
cm
ton
1
~
km
10
~
~
M
m
Gm
R
i
e
3
9
3
1
3
8
3
2
cm
ton
10
~
km
10
~
~
M
Gm
R
n
15. Derived quantities
Assume
• Surface gravity
• Escape speed
• “Breakup” rotation
• Schwarzschild radius
• “Relativity parameter”
Mass reduction ~ 20% when NS forms (carried away by
neutrinos, perhaps gravitational waves)
• Gravitational redshift factor
km
10
,
4
.
1 Sun
Chandra
R
M
M
M
Earth
11
2
10
2 g
R
GM
g
c
R
GM
v 6
.
0
2
esc
km
4
2
2
Schw
c
GM
R
4
.
0
|
|
2
c
2
2
grav
2
esc
Schw
2
Mc
W
v
R
R
R
c
GM
3
.
1
2
1
1
2
1
2
R
c
GM
z
ms)
5
.
0
(
2
kHz
2
2
3
Kepler
R
GM
16. Relativistic stellar structure eqs.
Since P=P() only (no dependence on T, equilibrium composition),
these two equations are enough to calculate the NS or WD structure.
dL/dr=..., dT/dr=... are important only for the thermal evolution.
First (numerical) solution for NSs: Oppenheimer & Volkoff 1939
17. The state of matter
changes with
density (T 0):
• “Ordinary” solid
• Solid + neutrons
• npe liquid
• More exotic
particles:
– muons
– mesons ,
– hyperons ,
– ???
• Quark matter?
18. Mass-
radius
relation
for NSs
Black (green) curves are for normal matter (SQM) equations of state.
Regions excluded by general relativity (GR), causality, and rotation constraints are indicated.
Contours of radiation radii R are given by the orange curves.
The dashed line labeled I/I = 0.014 is a radius limit estimated from Vela pulsar glitches (27).
from Lattimer & Prakash 2004
19. Expected thermal radiation
• Neutron stars are born in stellar core collapse: initially very hot, expected to
radiate thermally (~ blackbody) (Chiu 1964, Chiu & Salpeter 1964)
• Might be detectable in soft X-rays (difficult)
• Start of X-ray astronomy (Giacconi et al. 1962):
– several sources (quasars, etc.)
– growing theoretical interest in NSs
– at first no unambiguous detections of NSs (X-ray pulsars found by UHURU, 1971)
– no detections of pure, thermal radiators until much later
keV
1
.
0
~
K
10
5
.
1
4
4
1
Sun
6
4
2
L
L
T
T
R
L
20. Pulsars: discovery
1967: PhD student Jocelyn Bell &
her supervisor Anthony Hewish
detect a very regular Pulsating
Source of Radio (PSR 1919+21)
with P=1.377 s, initially “LGM 1”.
http://www.jb.man.ac.uk/~pulsar/Education/Sounds/sounds.html
23. How we know pulsars are NSs
• Association with supernova remnants (SNRs)
• Rotation of Crab pulsar
– Much faster ones (“millisecond pulsars”) found later
• Energy budget of SNR in rough agreement with energy lost
from rotating NS.
• Very high-energy (non-thermal) emission: likely relativistic
system
• Thermal emission (X-rays): emitting region 10 km
• Binary systems: Precise masses 1.25-1.45 Msun ~ MChandra
3
11
2
3
cm
g
10
4
3
3
4
G
G
R
GM
27. Other neutron stars
Several other classes of observed objects are also believed to
be NSs:
• X-ray binaries (some NSs, some black holes)
• “Soft gamma-ray repeaters” & “Anomalous X-ray Pulsars”
“Magnetars”
• Thermal X-ray emitters:
– bright central objects in SNRs
– fainter, isolated objects
• Radio transients (RRATs)
See tomorrow’s Lecture for details...