Hard%20X-ray%20view%20of%20nearby

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Hard X-ray view of nearby Star Forming Regions

S. Sciortino INAF-Osservatorio Astronomico di
Palermo
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COUP
Pi (E. Feigelson)? In 850 ks (13 days)? All ONC
Members vary in intensities and spectra Small
and BIG Flares plus Rotational Modulation Prot of
few days
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X-ray emission from (low-mass) YSOs

• Very X-ray luminous
• At 1 Msun, ltlog(LX)gt 30-31 (Sun
  log(LX)26.5-27.5)?
• Very hot
• Plasma at 10's MK always present
• gt100 MK during flares (Sun gt 10 MK only in
  flares)?
• Highly time variable
• Stochastic, big flares (up to 100 times), rot.
  modulation
• Class I/II Lx 2-3 times lower than Class III
• Often low metal abundance in emitting plasma
• Class I/II hotter X-ray spectra than Class III,
  but a soft (0.2-0.3 keV, accretion) component can
  be present

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As a results we do not know yet when X-rays
appear and start acting on the environment
likely influencing SF
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Open issues ....

• X-ray emission in Class-0 (likely traced in Hard
  X-ray)
• Effects on SF process
• Class I/II/III YSOs do emit quiescent Hard X-ray
  ?
• Is Hard emission due only to many small flares
  ...
• Hard X-rays during long lasting (big) flares
• Again, effects on SF process
• Accretion in YSOs
• How is it channeled? How is it regulated?
• Feedback processes?
• Chemistry of protoplanetary disks (X-ray induced
  ?)?
• How do complex molecules form?
• Catalyst processes and molecules?
• Isotopic ratios?

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Peering deep into dense cores of past/on-going
Star Forming Regions
BN/KL region The COUP sharp view
43 sources found, 18 new. 22 with
22.2ltlog Nh lt23.6

Grosso et al. (2005), ApJS
Red, 0.51.7 keV Green 1.72.8 keV Blue 2.88.0
keV
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• X-rays are an ingredient of the Open cluster
  size evolution of (pieces of) giant molecular
  clouds.
• Recent modeling of COUP data predicts X-ray from
  YSOs as a major ionization sources
• If X-rays suppress ambipolar di?usion, they
  may terminate growth of clusters and inhibit
• (or delay) future SF in their vicinity
• Moreover X-rays may have a role on the early
  evolution of circumstellar disk ( subsequent
  planetary system formation)

ORION (Lorenzani et al. 2007) BN-KL
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X-rays from Class-0 in Serpens SFR
Spitzer, IRAC 1 image
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Example solar flares
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X-ray flares and size of magnetic structures

• X-ray flares are classic tool to derive physical
  parameters of emitting region
• Use of dynamical information (decay time, etc.)
  allows derivation of physical characteristics of
  flaring region
• Flaring plasma must be magnetically confined,
  thus this allows to measure the size of
  individual magnetic structures
• Observed YSO flares typically scaled-up version
  of solar ones, BUT FEW CASES ....

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Analysis of COUP Flares
long lasting (? ??0 ks)? very hot plasma (100s
MK)? almost free decay fast temperature
decay Long loop 2 ? 1012 cm (? 0.1
AU!)? Confining B field 150 G
COUP 1343
very long lasting (? ?80 ks)? moderate T plasma
(?100 MK)? sustained heating slow temperature
decay Longish loop 1 ? 1012 cm (L/2 ? 2.5
R)? Confining B field 180 G
COUP 28
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How can these long loops be structured?

• Never seen in more evolved normal stars
• Stability problem respect to centrifugal force
• Orion YSOs are fast rotators (P ? 3-6 d)?
• Co-rotation radius typically at 3-4 R
• Long loops anchored on star only would be ripped
  open
• Solution loops connecting
• star and disk
• (at corotation radius)?
• Postulated by magnetospheric accretion scenario

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Magnetospheric accretion
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DROXO, A Deep Rho Oph XMM-Newton Observation
(500 ks, Pi S. Sciortino)?
Hardest spectrum WL 2/GY 92
MOS1 MOS2 PN

• Red 0.25 1.8 keV
• Green 1.8 3.7 keV
• Blue 3.7 7.5 keV
• 110 Sources found in the combined data

Elias 29
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Fluorescence observations and statistics

• 'Cold' Fe 6.4 keV line thus far detected in a
  number of cases
• One detection in YLW16A in ? Oph during an
  intense X-ray flare (Imanishi et al. 2001)?
• 7 cases of fluorescence in ONC YSOs (Tsujimoto et
  al. 2005) during intense X-ray flaring
• One detection in Elias 29 in ? Oph during
  quiescence and flaring (Favata et al. 2005), but
  the observation was short (34 ks long)?
• Lbol 26 Lbol,sun , Lacc 15-18 Lbol,sun (very
  high)?

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Fluorescence in ONC YSOs
850 ks Chandra Observation
BUT NO TIME RESOLVED SPECTROSCOPY
Tsujimoto et al. (2005), ApJS COUP Special Issue
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Fluorescence, as today understood ..

• Emission of X-ray radiation from photo-ionized
  cold material
• Photo-ionizing photons come from star, cold
  material in circumstellar disk
• If Fe I K? line at 6.4 keV is photo-ionized then
  photons energy need to be E gt 7.11 keV
• High-energy X-rays needed
• Fluorescence is a tracer of 'intimate
  relationships' between hard X-rays and cold
  material
• It can give important clues to the geometry of
  the circumstellar material

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DROXO 500 ks look of a YSO in rho Oph
Fe 6.4 keV fluorescent line appears EW 250
eV It Stays Up for following 300 ksec EW 150
eV Variability of Fe 6.4 keV line unrelated to
variation of thermal spectrum, too large EW for
hard photons in thermal spectrum Sustained
mechanism ionizing cold Fe must operate for
days (Giardino et al. 2007, submitted, cf.
Micela, Favata, Giardino Sciortino poster)?
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DROXO 500 ks look of a YSO in ? Oph - 2

• Possible explanation
• Collisional ionization of K-shell electrons by a
  beam of non-thermal electrons (cf. Emslie et al.
  1986)?
• Scenario
• In the magnetospheric accretion scenario,
  material is channeled in magnetic tubes from
  the disk to the star
• Long-duration flares in YSOs provides evidence
  for flaring associated in these accretion
  streams.
• The magnetic fields channelling the streams are
  stressed by differential rotation velocity
  between the star and the disk. This is a natural
  continuous engine for the reconnection events
  (and associated electron beams)?

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Diagnostics through Simbol-X

• Non-thermal electrons should be detectable
  through their brehmstralung radiation in hard
  (Simbol-X) X-ray bandpass (but invisible in the
  XMM observation).

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Quiescent Hard X-rays ?

• ALL X-ray emission of ONC low-mass YSO can be
  explained as continuous flaring emission with
  flare intensity following a power law (Caramazza
  et al. 2007)?
• A scaling relation between soft thermal and hard
  non-thermal X-ray emission has been found (Isola
  et al. 2007 submitted, cf. also the Isola et al
  poster) to hold over several dexs considering
  both solar (RHESSI archive data) and few stellar
  flares (BeppoSAX PDS archive data)?

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Quiescent Hard X-rays ? cont ..
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Simulations of ONC YSO X-ray emission as due only
to flares soft vs. hard emission scaling
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In a long observation Simbol-X may see the
quiescent hard non-thermal emission if present
in nearby SFR YSO ...
YSO

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Conclusions

• A long look of few selected SFRs with Simbol-X
  offers the unique opportunity to find whether
  very young (104 yr, still accreting) protostars
  actually emit X-rays impact on star formation
  process, and even (perhaps) on the earliest
  stages of planetary formation (e.g. large grains,
  planetesimals)?
• It opens the possibility to study the MHD
  acceleration process in high X-ray luminous YSOs
  .... a new laboratory for other magnetic/shock
  processes