Cosmic magnifying lenses distort view of distant galaxies

January 12, 2011

Looking deep into space, and literally peering back in time, is like experiencing the universe in a house of mirrors where everything is distorted through a phenomenon called gravitational lensing. Gravitational lensing occurs when light from a distant object is distorted by a massive object that is in the foreground.

Astronomers have started to apply this concept in a new way to determine the number of very distant galaxies and to measure dark matter in the universe. Though recent progress has been made in extending the use of gravitational lensing, a letter published in Nature on Jan. 13 makes the case that the tool may be even more necessary than originally thought when looking at distant galaxies. Download Full Image

Albert Einstein showed that gravity will cause light to bend. The effect is normally extremely small, but when light passes close to a very massive object such as a massive galaxy, a galaxy cluster, or a supermassive black hole, the bending of the light rays becomes more easily noticeable.

When light from a very distant object passes a galaxy much closer to us, it can detour around the foreground object. Typically, the light bends around the object in one of two, or four different routes, thus magnifying the light from the more distant galaxy directly behind it. This natural telescope, called a gravitational lens, provides a larger and brighter – though also distorted – view of the distant galaxy. These distortions, which stretch beyond the limits of the Hubble Space Telescope, can be effectively handled by a new space telescope on the drawing boards – the James Webb Space Telescope (JWST).

A very massive object – or collection of objects – distorts the view of faint objects beyond it so much that the distant images are smeared into multiple arc-shaped images around the foreground object. According to Rogier Windhorst, one of the letter’s authors and a professor at the School of Earth and Space Exploration in ASU’s College of Liberal Arts and Sciences, this effect is analogous to looking through a glass coke bottle at a light on a balcony and noticing how it is distorted as it passes through the bottle. Cosmologists such as Windhorst believe that gravitational lensing likely distorted the measurements of the flux and number density of the most distant galaxies seen in the recent deep near-IR surveys with the Hubble Space Telescope Wide Field Camera 3.

When you look back to when the universe was young, you are seeing extremely early objects (also known as "First Light’’ objects) that are very far away. The older and farther away the object, the more foreground universe there is to look through, which means the greater the chance that there will be something heavy in the foreground to distort the background image. This research suggests that gravitational lensing is likely to dominate the observed properties of very early galaxies, those that are at most 650 million to 480 million years old. The halos of foreground galaxies when the universe was in its heydays of star formation (about 3 billion to 6 billion years old) will gravitationally distort most of these very early objects.

“The very distant universe is like a house of mirrors that you visit at the state fair – there may be fewer direct lines-of-sight to a very distant object, and their images may reach us more often via a gravitationally-bent path. What you see is not what you’ve got!’’

Future surveys will need to be designed to account for a significant gravitational lensing bias in high-redshift galaxy samples. Only the JWST – if it gets finished as designed – can ultimately make sense out of this gravitationally biased distant universe because it will have exquisite resolution and sensitivity at longer wavelengths to disentangle these very distant objects from the foreground lensing galaxies. This work is too hard to do with Hubble’s Wide Field Camera 3 at redshifts z >= 10, because at Hubble’s resolution one literally can no longer see the forest for the trees at these extreme distances.

“Our suggestion of the possibility of large gravitational lensing biases in high redshift samples is of crucial importance to the optimal design of surveys for the first galaxies, which represent a central part of JWST’s mission,’’ Windhorst says. “This work clearly shows that we now need JWST – and its superb infrared resolution, dynamic range and sensitivity – more than ever to disentangle the First Light forest from the foreground trees.

"We will also need a next generation of object finding algorithms, since the current software is simply not designed to find these rare background objects behind such dense foregrounds. It’s like finding a few 'nano-needles' in the mother-of-all-haystacks.”

Nikki Cassis

marketing and communications director, School of Earth and Space Exploration

New dean's goal is an inspirational education experience for engineering students

January 12, 2011

Paul Johnson is the new dean of Arizona State University’s Ira A. Fulton Schools of Engineering. But he’s far from new to the leadership of the university and the engineering schools.

He’s been the engineering schools’ executive dean for the past four years – essentially the chief operating officer working under former dean Deirdre Meldrum. For two years previous to that, Johnson was the associate vice president for research for the university. Before that he was the associate dean of research for engineering.

Johnson has taught and conducted research at ASU since 1994, while continuing periodic work as a consultant to industry and public agencies. Prior to coming to the university, he spent several years as a research engineer for Shell Oil corporation.

Preparing for challenges

This wealth of experience has shaped his vision for the future of the Ira A. Fulton Schools of Engineering.

“Our mission is to produce new engineers prepared to succeed in a society that is more rapidly changing and technologically advanced than at any time in history,” Johnson says.

“We want our students to be adaptable to a fast-paced world and ready to pursue solutions to the most critical engineering challenges facing people everywhere,” he says.

To Johnson, this means creating an educational environment that offers much more than technical training. It means nurturing the spirit of inventiveness and innovation, and giving students solid grounding in entrepreneurship. It means teaching them to understand that decisions made by engineers can have significant impacts on the paths taken by society in public policy, economics and other areas.

An essential part of that education plan is allowing students to customize their academic experience at ASU and providing them opportunities to participate in hands-on applications of engineering outside of the classroom as early as possible.

“Today it takes far more than traditional coursework to attract students and then ensure they get a worthwhile education,” Johnson says. “Students are motivated to pursue engineering because they see the degree as the stepping stone that enables them to pursue careers in important areas such as energy, health care, environmental sustainability, security and defense, and more. The engineering schools that recognize this and evolve accordingly will be the great engineering schools of the 21st century.”

Optimizing opportunities Download Full Image

At the core of Johnson’s vision is a commitment to prepare the next generations of engineers to create the innovations that will shape our world by helping to solve its most pressing problems.

To accomplish this, he sees the schools of engineering optimizing opportunities for students to complete internships in business and industry, participate in university research, network through student chapters of national and international professional organizations, and use skills learned in the classroom to perform community service projects.

“Our faculty takes a collaborative, cross-disciplinary approach to engineering research,” Johnson says, “and they measure success by the impact their work has on their technical fields, our region and the world. Their job is to instill these values in students.”

ASU’s engineering faculty”has demonstrated a remarkable agility in its response to the quickly changing research funding environment,” says Stephen Phillips, director of the School of Electrical, Computer and Energy Engineering.

“Dean Johnson’s commitment to a multidisciplinary, multiple faculty approach for both research and degree programs built on a foundation of faculty members’ strengths will enable our students and faculty to outpace their peers,” Phillips says.

The new dean’s blueprint for leading the schools is clear: The role of everyone – faculty, administrators and staff – is first and foremost as teacher, mentor, supporter and promoter of ASU’s engineering students.

Bold transformation

 “Ultimately our goal is to provide students not just the education necessary to do engineering,” Johnson says, “but the inspiration to excel at engineering in ways that will improve people’s lives.”

Other schools talk about that goal, “but we are doing it,” he adds, “with bold efforts to transform how engineering education and engineering schools are organized, in ways that respond to changing times.”

“Paul understands that this is a turning-point moment for our engineering schools,” says Kyle Squires, director of the School for Engineering of Matter, Transport and Energy. “He well appreciates that engineering must develop unique strengths to meet new challenges while preserving the foundation that enables the advances that will define our research, teaching and service.  He is extremely dedicated to accelerating the impact of our schools.”

James Collofello, associate dean of Academic and Student Affairs, expects Johnson “to build on the bold initiatives” put in motion by the restructuring of the schools.

“He’s passionate about ensuring our students have one of the best educational experiences possible, and that they become successful as a result of their experience,” Collofello says.

Continuing to teach

Johnson earned a master’s degree and a Ph.D. in chemical engineering from Princeton University. His bachelor’s degree in the field was earned at the University of California, Davis.

His primary areas of research and teaching are environmental risk assessment and study of the movement and impacts of chemicals in the environment, as well as groundwater hydrology, aquifer management and the cleanup of contaminants from soil and groundwater.

He’s been editor-in-chief of the journal Ground Water Monitoring and Remediation since 2003.

He’s earned numerous awards from industry and government entities for research in those areas, and several leading teaching awards.

Even as he takes on the responsibilities of dean, Johnson will continue to teach, mentor students and pursue his research interests.

Joe Kullman

Science writer, Ira A. Fulton Schools of Engineering