Transcript e-EVN science in 2006-2007 Zsolt Paragi (JIVE), for the EXPReS project What will e-VLBI offer for us one day? Several Gbps data rates/telescope,

e-EVN science in 2006-2007
Zsolt Paragi (JIVE),
for the EXPReS project
What will e-VLBI offer for us one day?
Several Gbps data rates/telescope, two orders of magnitude
better sensitivity, “full” uv-coverage, flexibility…
What the e-EVN can offer today:
• Limited sensitivity and resolution compared to EVN, but…
• Some flexibility for rapid response science
• Rapid feedback, you know if it works, you know what you observe…
• … enables quick decision about more observations (VLBI or other)
• Easy access, easy use – high level of PI support
2008 Jan 29
EXPReS Progress meeting, Utrecht
Slide #2
Where are we now in capabilities…
Sensitivity and resolution in typical observations, 5 GHz
• e-EVN in 2007, 256 Mbps: 50 uJy/beam, ~6 mas
• e-EVN, 512 Mbps: 35 uJy/beam, ~6 mas
• e-EVN in 2008, 512 Mbps, 10 uJy/beam, ~6 mas (~1 mas with Ar)
• Full EVN (no Ar), 1024 Mbps, 12 uJy/beam, ~1 mas
• VLBA, 512 Mbps, 30 uJy/beam, ~1 mas
• VLBA+GBT, 512 Mbps, 12 uJy/beam
The e-EVN is reaching very competitive sensitivity in 2008, but resolution remains an issue.
2008 Jan 29
EXPReS Progress meeting, Utrecht
Slide #3
… and how far can we go
Sensitivity
• Great 1 Gbps test results; 10 Gbps technology is coming
• Stuck with max. 1 Gbps with current EVN! => actions by CBD
Resolution/imaging
• It would be crucial to get long baselines other than Ar and Sh
• Besides EVN telescopes, can we initiate a more global array
including Australian and Japanese telescopes?
Flexibility
• Is it possible at all to make the EVN respond to some triggers on
previously unscheduled dates? What needs to be done to achieve
this???
2008 Jan 29
EXPReS Progress meeting, Utrecht
Slide #4
e-VLBI activities in 2007
• Regular e-VLBI test observations in every six week (on average)
• 24h time is pre-allocated for science observation during tests
• Observing proposals now must be sent to normal EVN deadlines;
a new type of triggered proposal class, normal and spectral projects
supported
• Science operations at 1.6 and 5GHz, up to 256 Mbps
(Cm, Jb2, Mc, On, Tr, Wb)
• First 22 GHz test with Metsahovi in March 2007
• Australia and Shanghai demos, great success!; 512 Mbps in
Australia science demo observations, with small number of tels.
•Most recently: robust 512 Mbps operations, and 1 Gbps fringes!!!
2008 Jan 29
EXPReS Progress meeting, Utrecht
Slide #5
Science results from the ‘Oz-demo’
ATCA, Mopra and Parkes observations at 512 Mbps, correlated at JIVE.
Target: the nearby supernova in the LMC, only visible from the South.
One of the breathtaking
Hubble Space Telescope
images of SN1987A
2008 Jan 29
EXPReS Progress meeting, Utrecht
Slide #6
And with VLBI…
Various fits to the data to measure the size
of the expanding remnant.
Tingay et al., (in prep.)
Highest resolution image of SN1987A
so far (first VLBI!) – not bad for a
three telescope array. Countours shows
an earlier ATCA image.
2008 Jan 29
EXPReS Progress meeting, Utrecht
Slide #7
e-EVN science projects in 2006/2007
• Cyg X-3, 20 Apr/18 May 2006, 128 Mbps, Tudose et al.
• GRS1915+105, 20 Apr 2006, 128 Mbps, Rushton et al.
• LSI +61.303, 256 Mbps, 26 Oct 2006, Perez-Torres et al.
• Algol, 26 Oct/14 Dec 2006, 256 Mbps, Paragi et al.
• Calibrators near M81, 14 Dec 2006, 256 Mbps, Brunthaler et al.
• INTEGRAL microquasar candidates, 14 Dec 2006, Pandey et al.
• “double header” run, 15 XRBs, 29 Jan 2007, Rushton & Spencer
• Calibrators, 21 Feb 2007, 256 Mbps, Tudose et al.
• J2020+3631 microquasar candidate, 28 Mar 2007, 256 Mbps, Martí et al.
• Cyg X-3, 12-13 Jun 2007, 256 Mbps, Tudose et al.
• Stellar maser search, 22-23 Aug 2007, 32 Mbps, Langevelde et al.
• INTEGRAL source redo, 6-7 Sep 2007, 256 Mbps, Pandey et al.
• Type Ib/c SN 2007gr, 6-7 Sep 2007, 256 Mbps, Paragi et al.
2008 Jan 29
EXPReS Progress meeting, Utrecht
Slide #8
First refereed journal papers:
GRS 1915+105: Rushton et al. (2007), MNRAS 374, L47
Cyg X-3: Tudose et al. (2007), MNRAS 375, L11
Cyg X-3
Aftermath of a huge outburst
-first detection of polarisation on
VLBI scales in a microquasar
What PI’s really need is to be able to
monitor these events in (1) closely spaced
monitoring observations, (2) when they
happen, not on fixed dates.
2008 Jan 29
EXPReS Progress meeting, Utrecht
Slide #9
LSI 61+303 campaign:
• Binary XRB system, also source of very energetic gamma rays;
• What is the source of these? Earlier hypothesis: microquasar jet.
• Recent VLBA observations (Mioduszewski et al.) suggest an
interacting pulsar wind source instead
• MAGIC collaboration observations including e-EVN, VLBA, MERLIN, CHANDRA
in October 2006
The MAGIC telescope and a view of
its surroundings in La Palma. It is
capable of detecting very high energy
gamma rays.
The telescope is operated by the
MAGIC collaboration of 17 institutes
since 2004.
http://wwwmagic.mppmu.mpg.de/
2008 Jan 29
EXPReS Progress meeting, Utrecht
Slide #10
…and the results
• no ultimate answer on the nature of the binary yet
• radio and X-rays originate from a different population
of electrons, but
• there is indication for temporal correlation between
X rays and gamma rays
Albert et al. (2008), Astrophys. J. (accepted),
astro-ph/0801.3150
2008 Jan 29
EXPReS Progress meeting, Utrecht
Slide #11
IGR 17303-0601 results:
INTEGRAL source, with candidate
optical counterpart showing binary
nature, and associated(?) radio source
in NVSS.
e-VLBI confirms compactness, but measured
position is inconsistent with optical coords.
Not associated, radio source is not from
a microquasar jet – likely background AGN.
M. Pandey, Z. Paragi, P. Durouchoux,
H. Bignall, PoS(Dynamic2007)041
2008 Jan 29
EXPReS Progress meeting, Utrecht
Slide #12
CHARA and e-VLBI observations of Algol
Algol is one of the most famous variable stars, also known as beta Persei.
It is very nearby, only 26 parsecs away,
ideal for optical/radio interferometry
studies.
Algol is active from radio to the X-ray
bands, besides the optical variations
due to regular eclipses.
Artist’s impression on the close binary system
from the web. The K-subgiant is the source of
radio activity.
2008 Jan 29
EXPReS Progress meeting, Utrecht
Slide #13
The CHARA array
The CHARA array is located at Mount Wilson
in California, USA, and is operated by the
Center for High Angular Resolution for Astronomy
http://www.chara.gsu.edu/CHARA/
2008 Jan 29
EXPReS Progress meeting, Utrecht
Slide #14
CHARA results
CHARA fringes before
and after processing.
Resulted visibility
amplitudes vs. baseline
length are shown below.
Fitted orbital parameters to the data,
found geometry of the system.
Determined distance: 26.1±0.4 pc,
More accurate than HIPPARCOS!
Paragi et al., submitted to PoS
(Manchester MRU proceedings)
Csizmadia et al. (refereed paper in prep.)
2008 Jan 29
EXPReS Progress meeting, Utrecht
Slide #15
Algol, 14 December 2006 e-EVN run:
+
• Simultaneous optical photometry and e-EVN obs.
(5 GHz, 256 Mbps) during secondary minimum
observations
of such
•Dedicated
Source flared
– total intensity
andflares
circular polarization
will be challenging
even forWSRT
e-VLBI
variations
consistent between
and e-EVN data
• Flare emission ~2 mas offset from the CP peak
• Detected proper motion during the
10 hours run –fitted orbital parameters
of the AB close binary, but…
2008 Jan 29
EXPReS Progress meeting, Utrecht
Slide #16
Supernovae: and old story with e-EVN
• SN2001em was discovered on 15 September
2001 in UGC11794 galaxy (Pepenkova 2001).
Garrett et al. (2005)
• Redshift z~0.02 corresponding to a distance
of 80~Mpc.
• Filippenko and Chornok (2001) classified it
as type Ib/c, most likely Ic.
• Exceptional radio and X-ray luminosities
(off axis GRB, developing late radio emission
due to jet break?),
• Not quite a 1 mJy radio source
• EVN observations: Cm, Jb2, On, Tr, Wb
(128Mbps), +Arecibo 300m (64 Mbps)
at 18cm, on 2005 Mar 11
• Tentative detection (4.5 ) of the first real
faint target with e-VLBI
Paragi et al. (2005), MSAIt 76, 570
2008 Jan 29
EXPReS Progress meeting, Utrecht
Slide #17
SN 2007gr ToO observations
• SN2007gr was discovered on 15 Aug 2007
with KAIT (CBET 1034); identified as
Type Ib/c.
• Distance is about 7.3 Mpc, 10x closer than
SN 2001em was.
• VLA discovers 610 microJy radio source
(Soderberg 2007)
• e-EVN observations: Da, Jb2, On, Tr, Wb
(256Mbps), at 6cm, on 2007 Sep 6-7
• Firm detection (5.6 ) of the supernova
within the VLA error box
Paragi et al. (2007), ATel #1215
2008 Jan 29
EXPReS Progress meeting, Utrecht
Slide #18
The first
ATel message
from the
e-EVN
2008 Jan 29
EXPReS Progress meeting, Utrecht
Slide #19
Conclusion
• The e-EVN has participated in a variety of science observations,
contributed to results carried out in ambitious multi-waveband
projects.
• We ‘used’ the e-VLBI developments to stir a bit of noise around
the EVN, and attract new users.
• But more is needed to make e-EVN a very competitive, unique
instrument.
2008 Jan 29
EXPReS Progress meeting, Utrecht
Slide #20
What else astronomers want?
• Better sensitivity and *resolution*
• Will happen with new radio telescopes being connected soon:
Arecibo 300m — 256 Mbps spring 2008
Shanghai +2 new — 1 Gpbs available (not operationally yet)
Effelsberg 100m — expected spring 2008
Yebes 40m — expected in 2008
•
Better flexibility, not fixed dates, allow multiple epochs to
follow up transients!!!
in 2008 will get close to disk-recording VLBI resolution and
sensitivity, and will be more flexible for ToOs
will be challenging for telescopes as well as the correlator
2008 Jan 29
EXPReS Progress meeting, Utrecht
Slide #21