populations of galactic x-ray (compact) sources visible to spectrum-rg revnivtsev m., space research...
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Populations of GalacticPopulations of GalacticX-ray (compact) sources X-ray (compact) sources
visible visible to Spectrum-RGto Spectrum-RG
Revnivtsev M.,Revnivtsev M.,Space Research Institute;Space Research Institute;
Moscow, RussiaMoscow, Russia
Discrete X-ray emitters in the Galaxy
1. Binaries with relativistic objects – X-ray binaries. High mass and low mass companions
2. Single relativistic objects: cooling neutron stars, rotation powered pulsars..
3. Binaries with accreting white dwarfs4. Stars with active coronae, binary stars
(the most numerous sources)
Expected spatial distribution of CVs, LMXBs…
High interstellar absorption
Extragalactic sky
Galactic ISM
It is very hard to study Galactic sources
You should see through walls
But you often findsomething interesting and useful
ROSAT 1-2 keVsens.limit 10-12 erg/s/cm2
Severe absorption in the G.Plane
INTEGRAL 17-60 keVsens. limit ~10-11 erg/sec/cm2
Harder X-rays are extremely valuable for Galactic surveys – ART-XC
Why population studies?1. Search for sources to be studied
individually2. Properties of populations can tell us
about their formation… about interactions in binary systems
(MSW, GW, outflows?)3 …. about average properties of compact
objects (e.g. magnetic field, rotation rates at birth etc)
4 … about long term evolution of objects (e.g. accumulation/erosion of WD masses etc)
M31Bulge of the Milky Way
Only in our Galaxy we can study companions of X-ray binaries –>
clues to physical mechanisms of their evolution
Voss, Gilfanov 2006
LMXB
?
What is the origin of this break?
LEdd for NS binary
Revnivtsev et al. 2011
MS
WD
LogLx~37 -- boundary between main sequence and giants companions?
Kuranov et al..(preliminary)
LMXB age evolution?
Lx
L2 d
N/d
L
Illarionov, Sunyaev 1975
Campana et al. 1998
sec/104 3/73
28
36min ergsPBL
81061~ B G
Propeller effect
35
pro
pel
ler?
This is the reason of absenceof faint LMXBs? Task for Spectrum-XG
Simulated LMXBs in the Galactic bulge(sensitivity 10-13 erg/s/cm^2, no absorption)
High mass X-ray binaries
INTEGRAL view of the Gal.Plane
HMXB “hole” in the Galactic disk?
Lutovinov et al. (2012, in preparation)
Galactic HMXBs
Parameter space,reachable for Spectrum-XGIn total 100-200 sources!
Lx<1034-34.5 erg/sec
Study of HMXB population is beyond reach of telescopes like CHANDRA, XMM or NuSTAR
due to their limited fields of view
~2-3/sq.deg!!
figure of R.Krivonos
Cataclysmic variables
All sky survey – spatial distribution of cataclysmic variables
Revnivtsev et al. 2008
Post bounce (older?) systems wider spreaded?
Now only ~20 objectsSRG expects >100000
Howell et al. 2001
Numerical modeling of cataclysmic variables
Old and the most numerous
Littlefair et al. 2008
Low Mdot CVsaccumulate massin a long run?No WD erosion?
We need bias-freesurveys!
Zero age WD mass
Counting CVs in the Galaxy is a complicated problem: biases
One of the latest results:usage of wideuniform surveys of the sky - SDSS
Szkody et al. 2003
Typical CV discovery: 1)Dwarf nova outbursts, 2)classical nova 3)UV color excess…………
Optical selection of CVs
Selection: WD contributionin blue part of spectrum
Even this simple attempt to have less biasedsearch revealed a completely different
CV population
Gansicke et al. 2009
BeforeSDSS
SDSSsample
Colors and brightnesses of WD of different masses
Bias toward lower masses WDs?
T
Bergeron et al. 1995
CVs in X-rays
Dependson mass of WDand B-field
X-ray surveys
Spectrum-XG area
Van Paradijs & McClintock 1994O’Brien et al. 2002Mescheryakov et al. 2011
Problems of finding low-Lx
LMXBS(even worsefor qLMXB
MK as faint as >4-5!
Revnivtsev et al. 2011
IGR J17254
Extremely faint sources in crowded
regions
Hard targets-hunt for low Lx
LMXBs
SAX J1747
LMXB HMXB
CV
eROSITAenergy range
ART-XCenergy range
Spectra of CVs and Active Binaries
For populations studies –future X-ray surveys
Spectrum-XG(eROSITA+ART)
Stars - millionsCVs – 100 000 -500 000
Summary:Studies of populations provide us handles
on:1.formation of binaries2.mechanisms of their long term evolution3.On averaged properties of populations
(compact objects magnetic fields, spatial distribution/kinematic age etc…
Vital issue: algorithms of identification of Galactic sources among huge
number of sources expected inSpectrum-XG surveys