Hi All,

It has been a while since I last wrote a post, but here I am reporting again about whats going on in my life at the moment. I am writing to you from Heidelberg, Germany, where I’m currently attending the Max Planck summer school on “Statistical inference from astrophysical data”…

I’ve arrived at Heidelberg last Saturday night and since the school began on Monday I had Sunday to walk around the city a little bit. I didn’t do too much touring since I’ve done that on my previous visit, a few years back, but I did get the chance to meet one of the local students, with whom we collaborate, for lunch. By the way I forgot to mention it earlier but when I got to the airport I got a free upgrade to business class for the first time of my life and I have to tell you its a whole different experience. I’m not sure if I can go back to flying economy class now (although I have to ).

Anyway, on Monday morning I woke up very excited looking forward for the school. I have to tell you that until now I have not been disappointed. I heard some very interesting lectures from Bill Press and David Hogg including things about Bayesian statistics, Likelihood, Markov Chain Monte Carlo, Bootstrap, etc. I’m learning new things about statistics each day. It always amazes me how many things there are to be learned (that’s a good thing) and how many mistakes us scientist do when we statistically analyze our data. But hey we are just humans and we do try to figure out what are our mistakes and how to do things the right way.

Of Course you can’t visit Germany without drinking beer. So the organizers of the school made sure that on every afternoon we get a supply of beer while we work on our computer programs. Yesterday we also went up the mountain for a visit at the Max Planck Institute for Astronomy, where were had a BBQ (with beer of course). I also had a chance there to meet with one of their new faculty members, Joe Hennawi, with whom I had an interesting chat about strong gravitational lensing, which is a field which we both research. Today, the lectures were held at the university old (~200 years old) hall which is very unique. I hope to show you some pictures soon. Afterwards we had an organized boat tour on the river Neckar which was very nice.

Well, we have two days left in the school, and then I’m going back home. I hope this two days  will be as good as the last few days.

Hi All,

Last night I was lucky enough to attend (got free tickets) the opening ceremony of the Maccabiah. The Maccabiah is a big sport event held in Israel every 4 years. Jewish athletes from all over the world take part in it.

The ceremony began at 20:30 and lasted two and a half hours. It was very loonnngggg. However, I enjoyed it very much. It was very exciting to see all the different delegations from different nations walking on the field. All the athletes seemed very excited and so did their families who were a huge part of the crowd and kept cheering.

Some parts of the ceremony were boring though, especially the speeches part. But most of it was FUN!!! especially the fireworks which I love so much.

Anyway, here are some pictures.

Two for the price of one…well almost. Today the European space agency successfully launched two satellites, Herschel and Planck, into space on board an Ariane 5 rocket. A lot of people waited for this launch, as these two different satellites should provide us some new insights on the past of our universe….

Herschel is the largest infra-red space telescope with a mirror 3.5 meters big. Planck is a microwave telescope who will provide a more accurate map of the anisotropies in the cosmic microwave background radiation.

Anyway, since I was still visiting the Laboratoire d’Astrophysique de Marseille in France, I attended their special Herschel and Planck launch event. Since the institute is part of the European agency, it participates in these satellite projects. So about an hour before the launch, all the people gathered around in one of the big halls and heard a talk about the mission. Unfortunately, the lecture was in french so I went back to the office to do some work until the launch. I then came back to watch the launch on the big screen with all the people who gathered around. Everyone were very excited to see the rocket launch successfully into the air and celebrated by opening some champagne bottles (lucky me). There is nothing like have some champagne in the middle of a work day

Here are a few images from the event:

For the last week and a half I’ve been in Marseille, France. The main purpose of my visit was to attend the CosmoClusters workshop which ended last Wednesday. The workshop was, as you can understand from its name, about galaxy clusters. The workshop was great, lots of people (about 50) and therefore also a lot of lectures (also one of mine)…

I heard about the workshop from Prof. Jean-Paul Kneib. I met him in a supernova workshop in Israel a few months ago and he was kind enough to invite me to the workshop, so thanks Jean Paul. In the workshop various of subjects related to galaxy clusters were reviewed. Some people talked about the X-ray properties of clusters (A hot gas component in the cluster emits X-ray radiation). Some of the X-ray people expressed their desire for a new space wide-field X-ray telescope (good luck guys!!). Other people described how they explore how matter, mostly dark matter,  is distributed inside clusters. They study and model the mass distribution using gravitational lensing and also X-ray. One of my best friends, Elinor, also gave a provocative talk about her cluster modeling work. Her observational work actually suggest that the theoretical predictions, from the current cosmological model, are not consistent with the observed cluster mass distribution.  Her talk made many people (especially theorists) worried. Good job Elinor

I also gave a talk, It was actually on my birthday (May 5th). The talk was about strong gravitational lensing (see my feature article in the cosmicdiary website).  I reviewed our recent work in which we look for lensed arcs in massive galaxy clusters. These arcs are amazing. I hope to show you some of them soon here on the blog.

After my talk I was more relaxed and could finally go and celebrate my birthday together with Elinor and some other people from the workshop (Annamaria, Gael, Lauro, Stefan, Cosimo). First we went to get some dinner. While most of the people enjoyed Marseille sea food, I had a steak. Yeah, I know, you probably ask why have a steak while you are in Marseille and not sea food, but hey some people don’t like to eat fish, and I’m one of them (I got it from my mother side). Anyway, afterwards we of course went to a pub, an Irish pub. I like Irish pubs and Guinness, If there is good Guinness to be found. So after a pint of Guinness and also two car bombs (its a pint of Guinness together with Baileys and Jameson whiskey) I was in a very good mood and pretty much ready to go back to the hotel and get some sleep. All and all it was a great night.

As I mentioned at the beginning the workshop already ended but I’m still here in Marseille. I decided to stay for another week in order to work with some people here hoping to begin some new collaboration. My stay here is almost over (going back on Friday) and I’m looking forward for going back home to my family and friends, and to celebrate my birthday with them as well

That week was also my first week in my new apartment. This time I moved to an apartment on my own, with no roommates. It was the end of a difficult month of searching for an apartment and moving into it. The 100 years birthday celebration to the city was just in time then. The celebration is going to be held through out the city during the whole year.

The opening event was held on Saturday night, April 4. It was amazing !!! The stage that was build in the city main square (also called Rabin square)  was the biggest ever built there. On the top of the stage sat the whole Israeli philharmonic orchestra. Below it on the stage it self performed various artists and dancers, including bands on top of building roofs around the square and of course lots and lots of fireworks. The show ended with a huge public dance party right there in the main square. The link below is a short video clip of the show taken by my brother, Amnon (wait till the middle of the clip for some fireworks). Enjoy the music and the fireworks….Happy Birthday Tel-Aviv !!!

Tel-Aviv 100 Birthday

Chandra is a modern X-ray telescope with amazing capabilities, such as its superb spatial resolution of 0.5 arc seconds. It has both and imager so you can get an X-ray image of an astronomical object and both a spectrometer so you can analyze the object’s X-ray emission in more detail. Chandra has been used to observe many astronomical objects such as Supernovae remnants, Black holes, Galaxy clusters and may more.

One of the famous discoveries made by Chandra is the “Bullet” cluster. The “Bullet” cluster is a galaxy cluster. Galaxy clusters are large structures that encompass hundreds to thousands of galaxies. The main mass component of galaxy clusters is dark matter, a kind of matter which does not emit light (hence dark) and does not interact with ordinary (baryonic) matter.  Galaxy clusters also have an intra-cluster gas component which emits X-rays. The “Bullet” cluster (see image below; the blue and red colors are artificial) has been observed both by Chandra and by the Hubble Space Telescope (HST; an optical telescope). As seen in the image below, the cluster is at a merging stage when a small passed through the main one. The small halo that passed through, looks like a “bullet” in X-ray (the right red part in the image). The red parts represent  the X-ray emission observed y Chandra. The blue parts represent where most of the mass of the cluster is based the optical analysis of the gravitational lensing (see my feature article on that) properties of the cluster as observed by HST. As shown in the image there is a significant offset between the main mass parts (blue parts) and between the gas parts (red parts). This offset is believed to be caused due to the fact that dark matte, which constitutes most of the cluster mass, is collision-less and there for is not subject to the same “drag” forces which act on the cluster gas.  The “Bullet” cluster therefore provides an important evidence for the existence of dark matter and enable us to study its properties.

Anyway, back to the proposal. Chandra has an annual cycle which means that you have one chance every year to submit a proposal in which you ask for telescope observation time. If you don’t get it, you have to wait another year to submit you proposal again. This year it was my first time of submitting a Chandra proposal and we managed to finish the proposal just in time, on the last day, a few hours before the deadline. I wont go into the details of the proposal, hopefully we’ll get the time we applied for and when we’ll have some results (it will take at least a year from now) I hope that the cosmic diary will still be up and running so I can tell you all about it.

I hope to finish with it all by next week because one of our collaborators, Matthias, is arriving for a visit and I’m looking forward to working with him so I really have to clear my schedule.

As you probably recall, I got a free trip to Paris from Keren parents and was about to meet with Keren and Ben there (check out my “Weekend in Paris - Part 1″ post).

After falling asleep in my hotel at about midnight on Friday night, I got a phone call at about 1 am from Ben telling me that they have finally arrived at the hotel. He also said that unfortunately, Keren hurt her leg at the train station. I immediately went to there room to finally meet them. It was a happy reunion…

Still, reunion and all, the situation required Keren to go and get her knee stitched up.

The next morning I woke up to a beautiful morning, still cold but with sunny blue skies. A perfect winter day to tour the city. After breakfast we were all set to do some touring. We decided to go out to Champs Elysees avenue. At these point some of you will say: “Hey you’ve been there already the day before” and you would be right. Its just that it was Keren and Ben first time in Paris and the important thing for me was to spend some time with them. So anyway, after slowly walking around (remember Keren was limping because of her leg) we arrived at the Arch of Triumph. It was magnificent and I recalled how beautiful it was when a huge flag was hanging down in the middle of it when i visited Paris back in 1994.

From there we took the Metro to the Eiffel tower. Since it was a both a beautiful day and the weekend, the lines to go up to the tower were very long and we decided to skip that part of the tour.
We thought it was a good time to get some lunch so we went to a restaurant which is called Hipo (or something like that). Lunch was really really great. I had foie gras and afterwards a T-bone steak with gratin. and for desert my favorite, a hot chocolate souffle.

In the little time we had left, we went to the louvre museum were we saw the Mona Lisa, oh and also the inverted pyramid that appeared in the movie “De Vinci Code” (Thanks Keren for the pyramid reminder). Afterwards we had a small detour on the way back to the hotel, since I wanted to go to one of Paris famous old Delis called Fauchon. There were all kind of chocolates, cheese, and other delicates there. So i bought some chocolate truffles for Keren (it was her birthday the day before) and some camembert cheese for my parents and for my friend, Elinor. For Dinner we went out to a nice wine bar where we had a bottle of the local red wine which was very good (Ben even wrote down its name) and a plate of all kinds of cheese and cold cuts.

The following day, Sunday, the day of my flight back home, we went to Montmartre. A beautiful hill which overlooks the city within the city. On the top there is a beautiful church. Montmartre is where a lot of artist used to live and create their art. It is also where the famous old traditional night club, Moulin Rouge, is. Although I wished I could spend some more time there with Keren and Ben the time has come to say good bye. We had a last drink together and I was on my way back to the hotel and from there to the airport.

So there you go, sometime life surprise you. It was an unexpected delightful weekend.

Last Wednesday I got a phone call from Keren’s mom. Keren is my good friend and colleague who have  just finished her PhD (at Tel-Aviv university) and began her post doc in Chicago. She is married to Ben who is also an astrophysicist.  Anyway, Keren and Ben went to Marseille, France, to collaborate with Prof. Jean-Paul Kneib. Keren parents were suppose to fly to Paris and spend the weekend with them there. Unfortunately, there was family emergency, and they couldn’t go. Instead, they offered the flight ticket and hotel room to me.

On Thursday afternoon, after a 24 hour notice, I found my self on a plane, going to Paris. Since I got to my hotel at around midnight, I got straight into bed and went to sleep. On Friday morning, I opened my eyes. and it took me a couple of minutes to really realize that I’m in Paris. I opened the window, it was very cold and cloudy, and from time to time some snow flakes rained down. After a light french breakfast (Croissants
and baguette) I was set to go out and tour the city.  

I walked from my hotel south to the Notre Dame cathedral and met there with Orit, the girl that got the other free flight ticket and spend her time in Paris at a friends house. The cathedral was beautiful both on the inside and on the outside. I especially liked the “Flying Buttress” which support one side of the cathedral. In front of the cathedral there is also what is called “Point Zero”, the point from which the french measure distances to everywhere in France. Strangely enough, despite the cold, there were some Scottish men walking around in short Scottish kilts.

After the visit in Notre Dame, we went to the Pompidou center, a strange looking art/shopping mall center. From there we went south of the river to meet Orit friend in the university and had lunch with him. Afterwards we continued touring the city. We saw the pantheon, Luxembourg gardens and a lot more and finally made it to the Eiffel tower. 

It was already 17:30 in the afternoon and the top of the Eiffel tower was in the clouds so we decided not to go up. At that point Orit went back to her friends house and I continued to Champs Elysees avenue and from there back to my hotel. I went out again to get dinner and some beer at a …. no, not a french restaurant or bar but at an Irish bar close by. After getting some bar food and a couple of pints of Guinness I got back to the hotel and waited for Keren and Ben who were suppose to arrive on the train from Marseille…..To be continued…..

Today it is an election day in Israel, yes again !!! It seems that in the ten or so last years the political situation is unstable so we have an election about every two years instead of every four. This time its been three years since the last election. Actually, the day after the previous election was a day to remember. The previous elections were held on March 28, 2006. On that day, I went to vote and right afterwards I hopped on a plane, with a large group of friends, and went to Turkey. The purpose of our trip was to observe the total solar eclipse on March 29.

The total eclipse was amazing !!! It happened in mid day. We observed it from an historic site near the city of Anatalya. Although I’ve seen partial eclipses before, nothing prepared me for the thrilling experience of a total eclipse. As we were just minutes away from total eclipse, when the moon’s shadow covered almost the entire sun, the sunny day was starting to look more like a night, the temperatures dropped, high altitude clouds were beginning to fill the clear skies, and we started to notice a few stars in the sky.

And then it happened ! a beautiful total solar eclipse, beginning with what is called a diamond ring effect. Then, what seems as a black sun engulfed in white flames. People around were so excited they started screaming. We all were ecstatic. One of the thoughts that came to my mind was what did the ancients think when they experienced a total eclipse. With no physical explanation at hand, I could understand why to them it must have felt like the end of the world was coming or something like that. Anyway, after a few exciting minutes the sun began to come out of the moon’s shadow and we all wished it could have lasted a little bit longer.

Well, back to reality. There was nothing special about the election day today. I got up early in the morning (no idea why, probably because I’m getting old ) and hopped on a bus to my home town, Holon, where I’m registered to vote. I arrived at my old high school, where the vote took place, and met my parents there. Afterwards I got back to Tel-Aviv. Unfortunately the weather is bad today, very strong winds. Since election day is an official day off, I was hoping to go out and walk around the city with friends. If we could only have the sunny warm weather we had a couple of days ago it would have been great. Oh well, lets hope that the next election day, when ever it might be, be a better day and a more hopeful day than this one.