1. AUSAC March 17-18 2008 VLBI @ Arecibo Tapasi Ghosh, Chris Salter, Arun Venkataraman Outline: 1. The Present Capability & Operations 2. Post-painting Observations 3. eVLBI 4. Arecibo’s VLBI future in the next decade

2. AUSAC March 17-18 2008 1.1 Arecibo’s existing VLBI capability VLBA4 DAR/Formatter MK5A Max 1-GHz IF The Big Dish ( Gain~10k/Jy,SEFD~3-5 Jy ) Correlator Internet FedEx 1024 Mbps256 MHz (max) 2 x 8, 16 MHz.05,.5 (#1,2 Rxs), 1 GHz 327, L, S,S-High, C, C-High, X Total data rateTotal single-pol RF Bandwidth # of BBCs & Max ∆ν/BBC Max. IF bandwidth/Rx Receivers Co-Observing Networks: 1. VLBA + Ar & the High Sensitivity Array (HSA, includes Y, GBT, EF) 2. European VLBI Network + Ar 3. Global - Network 4. eVLBI (Real-time VLBI via internet: as yet with the EVN only, through EXPReS)

3. AUSAC March 17-18 2008 A continuum observation, =18-cm, data-rate=512 Mbps, i.e. 128MHz of RF bandwidth, 2pol, 8-BBC, 8MHz/BBC,  = 120 minutes on source: 1  Image noise = 2.7  Jy/beam 6.4  Jy/beam EVNmax (@ 1Gbps,256MHz RF)+Ar -Ar 1  Image noise = 2.5  Jy/beam 4.7  Jy/beam Global(EVN+VLBA+Y27+Gb)+Ar -Ar 1  Image noise = 3.8  Jy/beam 9  Jy/beam EVN (same config. @512Mbps)+Ar -Ar 1  Image noise = 3.27  Jy/beam 3.8, 4.5, 3.9, 7.1  Jy/beam HSAmax (VLBA+Y27+EF+GB+Ar) -Ef (only), -GB, -Y27, -Ar 1.2 Arecibo’s Contribution to Various Arrays A spectral-line observation, =18-cm, 64 channels over 1-MHz, 2 pol, 120mins. 0.125 Jy/beam/ch 0.32 1.50.1550.3Jy/beam/ch VLBA+Y27+Gb+ARVLBA+Y27+GBVLBAEVN+AREVN

4. AUSAC March 17-18 2008 2. VLBI Highlights Post-Painting A study of the Zeeman effect for compact components in ULIRGs +3mG-3mG Robishaw, Heiles & collaborators have discovered many components with Zeeman splitting in majority of the OH megamaser galaxies observed at Arecibo (e.g. single dish, Stokes-V spectrum of IIIZw35, in the fig here). These yield line-of-sight fields of 0.3- 18 mGauss. However, to resolve them spatially, recent VLBI observations have been taken on IIIZw35 using the HSA (5mJy peaks/deeps of the stokes V plots). It will help delineate if all of the Zeeman effect seen is coincident with the VLBI OHM components (seen by Para et al.) or, some of the field detection is associated with the large scale ISM field in these galaxies, which in turn, helps investigating the origin of magnetic fields in these systems (i.e. in situ dynamo VS flux-freezing of galactic fields during mergers).

5. AUSAC March 17-18 2008 2. VLBI Highlights Post-Painting ( contd.) Jet and Counter-Jet emission in giant FRI radio galaxy, NGC315 Jet acceleration has been measured from proper motion studies of the knots Closest RG, 1mas=0.4pc Recent HSA observations at 5GHz (+ upcoming 8.4 GHz) will allow Giovannini et al. to map the weak (<0.02 mJy/beam) counter-jet with at least 20:1 dynamic range, and make significant improvement in radio-jet physics from detailed spectral-index and polarization studies at mas resolution.

6. AUSAC March 17-18 2008 Measuring the expansion velocity of SN2008D associated with the transient X-ray source in NGC2770 (Target of Opportunity; Paragi et al, 5th Feb2008). 2. VLBI Highlights Post-Painting ( contd.) The supernova SN2008D was detected in NGC2770, in Jan 08 by Swift as an X-ray transient, while observing SN2007uy (discovered in Dec.2007). It was about 2 mJy at the first VLBI epoch (5-6 February 2008, Global, 5-GHz), and unresolved. WSRT synthesis map from the same observations shows the bright SN2008D in the center, SN2007uy is the second brightest source, and some diffuse emission around the centre of the galaxy. Second epoch of observation is due tomorrow.

7. AUSAC March 17-18 2008 3. eVLBI EXPReS  PRISANET (PR) of the Arecibo Obs./UPR.  AMPATH (US) of Florida Intl. Univ.  Abilene (US) of Internet 2.  SURFnet (NL) of SURFnet BV. Arecibo is a member of the European EXPReS project. The goal is to achieve up to 1Gbps data rate to a real-time correlator (JIVE) over the internet. Present status :155Mbps shared with three UPR campuses, ATM line 200Mbps Internet-2 for AO only + borrowed ~300 Mbps from UPR’s during eVLBI, allowing 512 Mbps observation (See Arun’s talk for more) Any Day Now:

8. AUSAC March 17-18 2008 3. eVLBI EXPReS (contd.) 5th Feb 2008, test over the existing OC3 (155Mbps-shared with UPR) line: Arecibo data arriving at JIVE @64Mbps @128Mbps Fringe amplitude for 64Mbps Jb - TrJb - Wb Jb - ArTr - Wb Tr - Ar Wb - Ar Fringe amplitude for 128 Mbps Jb - TrJb - Wb Jb - ArTr - Wb Tr - ArWb - Ar QSO 3C395

9. AUSAC March 17-18 2008 4. Arecibo’s VLBI future When appropriate, upgrade to Digital Data acquisition rack (iBOB2/VDBE2/ ?) Appropriate data recorder/transport (MK5C, Mk5C-, eVLBI /?) -- Need to be ordered by September 2008 Join VSOP2 (at 8-GHz) Join Radioastron (327, 18-cm, 6-cm) Explore options for a supplementary antenna to improve efficiency of phase-referenced VLBI, etc. (Join Geodatic VLBI runs via the “VLBI2010” program?)

10. AUSAC March 17-18 2008 4.1 Arecibo’s VLBI future in the next decade VLBA will be enhanced to a 4-Gbps network allowing 1GHz RF bandwidth used for VLBI. This will be equivalent to having 10 X 40-m dishes. EVLA and the GBT will also have extended bandwidth, making up for the perhaps loss of Arecibo (in continuum SNR). However, this will not help observations of spectral line, and variable sources. Even without any extra equipment, Arecibo will still provide 4/5 times SNR improvements in such VLBI maps in the next decade (if it were allowed to exist for the astronomers then).