Mark Devlin

My research focuses on experimental cosmology at millimeter and submillimeter wavelengths.  Cosmology is the study how the Universe came into being and how it evolved into what we see today.  Unlike a traditional astronomer who might study an individual star or galaxy to determine its properties, I collect data from which I make statistical inferences about the evolutionary history of the Universe.  To this end, I design and build sophisticated instrumentation and telescopes which I use to observe from high-altitude balloons and the high-plateaus of Chile.

When we look out into the nearby Universe we see that it is very ordered.  There are stars like our Sun with planets orbiting them. Our Galaxy is composed of stars that orbit its center.  Our Galaxy, in turn, is part of a large group of galaxies that interact weakly.  This hierarchical ordering extends to scales of approximately one-billion light-years.  For comparison, our Galaxy is about one-hundred-thousand light years in diameter.  These observations lead us to pose a number of questions such as:

What was the state of the Universe near its beginning?  These initial conditions will set the stage for the growth of structure.

What are the fundamental parameters that govern the formation of structure and what are their values?

How does structure evolve over time?

Current Work

I am currently involved in four separate projects that span a wide range of scientific goals that explore the questions posed above.

BLAST:  I am the PI of an instrument called the Balloon-borne Large Aperture Submillimeter Telescope - BLAST.  This instrument is designed to produce confusion-limited (approximately one source for every 30 pixels) and wide-area extragalactic and Galactic surveys from a long-duration balloon (LDB) platform.  BLAST’s successful test-flight in September 2003 paved the way for a series of long-duration (5-15 day) science balloon-flights at altitudes of 40 km.  At this altitude the atmospheric transparancy is > 99% in the BLAST bands. Its focal-plane arrays (with 280 bolometric detectors) provide simultaneous images at 1.2, 0.86 and 0.6 THz with resolutions of 35-70 arcseconds, respectively, over an 86 square arcminute field of view.

By providing the first sensitive large-area (0.5 - 40 square degrees) surveys at these short sub-mm wavelengths, BLAST will address some of the most important galactic and cosmological questions regarding the formation and evolution of stars, galaxies, and clusters.  Galactic and extragalactic BLAT surveys will: (i) identify large numbers of high-redshift galaxies; (ii) measure photometric redshifts, rest-frame far-infrared luminosities, and star formation rates thereby constraining the evolutionary history of the galaxies that produce the far-infrared and submillimeter background; (iii) detect cold pre-stellar sources associated with the earliest stages of star and planet formation; (iv) make high-resolution maps of diffuse Galactic emission over a wide range of galactic latitudes.  BLAST had its first long-duration balloon flight from Kiruna, Sweden to Victoria Island, Canada in June of 2005.   We plan an additional flight in late 2006 from Antarctica that will have a full 10 - 14 days of integration, which should complete our goals.  More information on BLAST  can be found at:  http://chile1.physics.upenn.edu/blastpublic

ACT: Another major project is the Atacama Cosmolgy Telescope - ACT.  This 6-meter-diameter telescope will utilize 3000 bolometric detectors operating at 150, 220, and 270 GHz.  ACT will map over 100 square degrees with an error of 2 µK for $1.7 arcmin X 1.7 arcmin pixels.  We will identify 500 to 1000 clusters of galaxies though the Sunyaev-Zel'dovich (SZ) effect.  By studying these clusters with masses greater than $1014 Msun (1014 times the mass of the Sun), ACT will probe the evolution of cosmic structure and place limits on cosmological parameters including the mass of the neutrino to 0.1 eV.  The high resolution and sensitivity of the instrument will allow us to probe the total mass distribution directly on length scales of ~1 mega-parsec at redshifts between 1 and 2 by looking at gravitational lensing of the Cosmic Microwave Background (CMB) by intervening matter.  We anticipate having the telescope constructed at the site in Chile in mid-2006 with the first light on a test instrument in late 2006 and the final instrument in place in 2007.  We will observe through 2009.

Penn Array: I am also the PI of a project to build a 90 GHz receiver for the National Radio Astronomy Observatory's (NRAO's) 100 meter Green Bank Telescope (GBT).  This receiver has 64 transition edge sensor (TES) bolometers.  This facility instrument will provide 90 GHz mapping capability for the GBT. It will address a wide variety of scientific goals e.g. studies of large-areas of the Galactic plane and mapping the internal structure of SZ clusters.  The receiver will be completed in the fall of 2005 and is scheduled for its first light in the winter of 2006.

PAPPA:  The Primordial Anisotropy Polarization Pathfinder Array PAPPA will measure the polarization of the CMB and search for the signature of gravity waves excited during an inflationary epoch shortly after the Big Bang. \pappa\ combines sensitive TES detector technology with phase-sensitive correlation techniques from radio astronomy to build a ``polarimeter-on-a-chip'' scalable to the large (kilopixel) arrays anticipated for future space missions.  My group is responsible for the balloon gondola and telescope.  We anticipate a first flight in 2006 or 2007.

• At University of Pennsylvania since 1996